├── .github ├── dependabot.yml └── workflows │ ├── ci.yml │ └── release.yml ├── .gitignore ├── LICENSE ├── README.md ├── build.gradle.kts ├── gradle ├── libs.versions.toml └── wrapper │ ├── gradle-wrapper.jar │ └── gradle-wrapper.properties ├── gradlew ├── gradlew.bat ├── settings.gradle.kts └── src ├── main ├── java │ └── pl │ │ └── allegro │ │ └── tech │ │ └── boot │ │ └── leader │ │ └── only │ │ ├── LeaderOnlyBeanPostProcessor.java │ │ ├── LeaderOnlyConfiguration.java │ │ ├── LeadershipProxyFactory.java │ │ ├── api │ │ ├── ConnectionStringCannotBeEmptyException.java │ │ ├── CuratorLeadershipCustomizer.java │ │ ├── Leader.java │ │ ├── LeaderLatchCannotStartException.java │ │ ├── LeaderLatchCannotStopException.java │ │ ├── LeaderOnly.java │ │ ├── Leadership.java │ │ ├── LeadershipAcquisitionCallback.java │ │ ├── LeadershipChangeCallbacks.java │ │ ├── LeadershipFactory.java │ │ └── LeadershipLossCallback.java │ │ └── curator │ │ ├── ConnectionStringConverter.java │ │ ├── CuratorLeadership.java │ │ ├── CuratorLeadershipConfiguration.java │ │ ├── CuratorLeadershipFactoryImpl.java │ │ └── CuratorLeadershipProperties.java └── resources │ └── META-INF │ └── spring │ └── org.springframework.boot.autoconfigure.AutoConfiguration.imports └── test └── java └── pl └── allegro └── tech └── boot └── leader └── only ├── api ├── LeaderChangeCallbacksTest.java ├── LeaderOnlyTest.java └── TestLeadership.java ├── curator ├── ConnectionStringConverterTest.java └── CuratorLeadershipTest.java └── fixtures ├── SampleApplication.java └── SampleLeaderOnlyExecutor.java /.github/dependabot.yml: -------------------------------------------------------------------------------- 1 | version: 2 2 | updates: 3 | - package-ecosystem: "gradle" 4 | directory: "/" 5 | schedule: 6 | interval: weekly 7 | open-pull-requests-limit: 10 -------------------------------------------------------------------------------- /.github/workflows/ci.yml: -------------------------------------------------------------------------------- 1 | name: Java CI with Gradle 2 | 3 | on: 4 | push: 5 | branches: [ main ] 6 | paths-ignore: 7 | - 'README.md' 8 | pull_request: 9 | 10 | jobs: 11 | build: 12 | runs-on: ubuntu-latest 13 | steps: 14 | - uses: actions/checkout@v4 15 | - uses: actions/setup-java@v4 16 | with: 17 | distribution: 'temurin' 18 | java-version: 17 19 | - uses: gradle/actions/setup-gradle@v4 20 | - run: ./gradlew check 21 | -------------------------------------------------------------------------------- /.github/workflows/release.yml: -------------------------------------------------------------------------------- 1 | name: Publish package 2 | 3 | on: 4 | release: 5 | types: [ created ] 6 | 7 | jobs: 8 | publish: 9 | 10 | runs-on: ubuntu-latest 11 | steps: 12 | - uses: actions/checkout@v4 13 | - uses: actions/setup-java@v4 14 | with: 15 | distribution: 'temurin' 16 | java-version: 17 17 | - uses: gradle/actions/setup-gradle@v4 18 | - run: ./gradlew publishToSonatype closeAndReleaseSonatypeStagingRepository 19 | env: 20 | SONATYPE_USERNAME: ${{ secrets.SONATYPE_USERNAME }} 21 | SONATYPE_PASSWORD: ${{ secrets.SONATYPE_PASSWORD }} 22 | GPG_KEY_ID: ${{ secrets.GPG_KEY_ID }} 23 | GPG_PRIVATE_KEY: ${{ secrets.GPG_PRIVATE_KEY }} 24 | GPG_PRIVATE_KEY_PASSWORD: ${{ secrets.GPG_PRIVATE_KEY_PASSWORD }} 25 | -------------------------------------------------------------------------------- /.gitignore: -------------------------------------------------------------------------------- 1 | # Ignore Gradle project-specific cache directory 2 | .gradle 3 | 4 | # Ignore Gradle build output directory 5 | build 6 | 7 | .idea 8 | 9 | .gradletasknamecache -------------------------------------------------------------------------------- /LICENSE: -------------------------------------------------------------------------------- 1 | Apache License 2 | Version 2.0, January 2004 3 | http://www.apache.org/licenses/ 4 | 5 | TERMS AND CONDITIONS FOR USE, REPRODUCTION, AND DISTRIBUTION 6 | 7 | 1. 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We also recommend that a 185 | file or class name and description of purpose be included on the 186 | same "printed page" as the copyright notice for easier 187 | identification within third-party archives. 188 | 189 | Copyright {yyyy} {name of copyright owner} 190 | 191 | Licensed under the Apache License, Version 2.0 (the "License"); 192 | you may not use this file except in compliance with the License. 193 | You may obtain a copy of the License at 194 | 195 | http://www.apache.org/licenses/LICENSE-2.0 196 | 197 | Unless required by applicable law or agreed to in writing, software 198 | distributed under the License is distributed on an "AS IS" BASIS, 199 | WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 200 | See the License for the specific language governing permissions and 201 | limitations under the License. -------------------------------------------------------------------------------- /README.md: -------------------------------------------------------------------------------- 1 | # Leader Only Spring Boot Starter 2 | 3 | [![Java CI with Gradle](https://github.com/allegro/leader-only-spring-boot-starter/actions/workflows/ci.yml/badge.svg)](https://github.com/allegro/leader-only-spring-boot-starter/actions/workflows/ci.yml) 4 | ![Maven Central](https://img.shields.io/maven-central/v/pl.allegro.tech.boot/leader-only-spring-boot-starter) 5 | 6 | Sometimes it is crucial to perform some action only on one application node. 7 | This library makes this boring task easy. 8 | 9 | - Integrates with [Spring Boot 3](https://github.com/spring-projects/spring-boot) 10 | - Leverages [Apache Curator](https://curator.apache.org/) 11 | - Handles multiple locks at once 12 | 13 | ## Installation 14 | 15 | ### Maven 16 | 17 | ```xml 18 | 19 | 20 | pl.allegro.tech.boot 21 | leader-only-spring-boot-starter 22 | 1.1.0 23 | 24 | 25 | org.apache.zookeeper 26 | zookeeper 27 | 3.9.0 28 | 29 | 30 | ``` 31 | 32 | ### Gradle 33 | 34 | ```groovy 35 | dependecies { 36 | implementation "pl.allegro.tech:leader-only-spring-boot-starter:1.1.0" 37 | implementation "org.apache.zookeeper:zookeeper:3.9.0" 38 | } 39 | ``` 40 | 41 | ## Usage 42 | 43 | ```java 44 | import pl.allegro.tech.boot.leader.only.api.Leader; 45 | import pl.allegro.tech.boot.leader.only.api.LeaderOnly; 46 | 47 | @Leader("leader-identifier") // creates new leader latch with identifier 48 | public class Sample { 49 | 50 | @LeaderOnly 51 | public Integer performActionOnlyOnLeader() { 52 | return veryExpensiveOperation(); // this will be performed only at leader node 53 | } 54 | 55 | public Integer performActionOnEveryNode() { 56 | return somethingCheapToPerform(); // this will be performed at all nodes 57 | } 58 | } 59 | ``` 60 | 61 | `@Leader` annotation enhances `@Component` and will add a candidate 62 | for auto-detection when using annotation-based configuration and classpath scanning. 63 | 64 | It is also possible to handle leadership status changes. To do so, bean annotated with `@Leader` has to 65 | implement `LeadershipChangeCallbacks` interface. 66 | 67 | ```java 68 | import pl.allegro.tech.boot.leader.only.api.Leader; 69 | import pl.allegro.tech.boot.leader.only.api.LeaderOnly; 70 | import pl.allegro.tech.boot.leader.only.api.LeadershipChangeCallbacks; 71 | 72 | @Leader("leader-identifier") // creates new leader latch with identifier 73 | public class Sample implements LeadershipChangeCallbacks { 74 | 75 | @LeaderOnly 76 | public Integer performActionOnlyOnLeader() { 77 | return veryExpensiveOperation(); // this will be performed only at leader node 78 | } 79 | 80 | public void onLeadershipAcquisition() { 81 | leadershipSetUp(); // this will be performed when node becomes a leader 82 | } 83 | 84 | public void onLeadershipLoss() { 85 | leadershipCleanUp(); // this will be performed when node stops being a leader 86 | } 87 | 88 | public Integer performActionOnEveryNode() { 89 | return somethingCheapToPerform(); // this will be performed at all nodes 90 | } 91 | } 92 | ``` 93 | 94 | ## Configuration 95 | 96 | ```yaml 97 | curator-leadership: 98 | connection-string: localhost:2181 # only required property 99 | namespace: /leader-only 100 | timeout: 101 | session: 100ms 102 | connection: 100ms 103 | wait-for-shutdown: 100ms 104 | retry: 105 | max-retries: 3 106 | max-sleep-time: 1s 107 | base-sleep-time: 200ms 108 | auth: 109 | scheme: digest 110 | username: username 111 | password: password 112 | ``` 113 | 114 | [Apache Zookeeper](https://zookeeper.apache.org/) & 115 | [Apache Curator](https://curator.apache.org/) 116 | are technologies that drives selecting leader. 117 | 118 | ## What if you don't want to use Zookeeper? 119 | 120 | You can make your own `Leadership` implementation and add your `LeadershipFactory` bean to Spring context. 121 | If you want to know more, check out this [example](src/test/java/pl/allegro/tech/boot/leader/only/api/LeaderOnlyTest.java). 122 | -------------------------------------------------------------------------------- /build.gradle.kts: -------------------------------------------------------------------------------- 1 | import org.gradle.api.tasks.testing.logging.TestExceptionFormat 2 | import java.time.Duration 3 | 4 | plugins { 5 | `java-library` 6 | `maven-publish` 7 | alias(libs.plugins.springBoot) 8 | alias(libs.plugins.springDependencyManagement) 9 | alias(libs.plugins.axionRelease) 10 | alias(libs.plugins.nexusPublish) 11 | signing 12 | } 13 | 14 | repositories { 15 | mavenCentral() 16 | } 17 | 18 | group = "pl.allegro.tech.boot" 19 | version = scmVersion.version 20 | 21 | java { 22 | withSourcesJar() 23 | withJavadocJar() 24 | toolchain { 25 | languageVersion.set(JavaLanguageVersion.of(17)) 26 | } 27 | } 28 | 29 | dependencies { 30 | annotationProcessor("org.springframework.boot:spring-boot-configuration-processor") 31 | 32 | api("org.springframework.boot:spring-boot-starter-aop") 33 | api("org.springframework.boot:spring-boot-autoconfigure") 34 | api(libs.bundles.curator) 35 | 36 | testRuntimeOnly("org.junit.jupiter:junit-jupiter-engine") 37 | 38 | testImplementation(platform(libs.testcontainers)) 39 | testImplementation("org.springframework.boot:spring-boot") 40 | testImplementation("org.springframework.boot:spring-boot-starter-test") 41 | testImplementation("org.testcontainers:testcontainers") 42 | testImplementation("org.testcontainers:junit-jupiter") 43 | testImplementation("org.junit.jupiter:junit-jupiter-api") 44 | testImplementation(libs.awaitility) 45 | testImplementation(libs.zookeeper) 46 | } 47 | 48 | tasks.bootJar { 49 | enabled = false 50 | } 51 | 52 | tasks.jar { 53 | enabled = true 54 | } 55 | 56 | tasks.test { 57 | useJUnitPlatform() 58 | testLogging { 59 | events("passed", "skipped", "failed") 60 | exceptionFormat = TestExceptionFormat.FULL 61 | } 62 | } 63 | 64 | publishing { 65 | publications { 66 | create("sonatype") { 67 | from(components["java"]) 68 | pom { 69 | name = "leader-only-spring-boot-starter" 70 | description = "Spring Boot starter for leader only processing" 71 | url = "https://github.com/allegro/leader-only-spring-boot-starter" 72 | licenses { 73 | license { 74 | name = "The Apache License, Version 2.0" 75 | url = "http://www.apache.org/licenses/LICENSE-2.0.txt" 76 | } 77 | } 78 | developers { 79 | developer { 80 | id = "wpanas" 81 | name = "Waldemar Panas" 82 | } 83 | } 84 | scm { 85 | connection = "scm:git@github.com:allegro/leader-only-spring-boot-starter.git" 86 | developerConnection = "scm:git@github.com:allegro/leader-only-spring-boot-starter.git" 87 | url = "https://github.com/allegro/leader-only-spring-boot-starter" 88 | } 89 | } 90 | } 91 | } 92 | repositories { 93 | maven { 94 | val releasesRepoUrl = uri("https://oss.sonatype.org/service/local/staging/deploy/maven2/") 95 | val snapshotsRepoUrl = uri("https://oss.sonatype.org/content/repositories/snapshots/") 96 | url = if (version.toString().endsWith("SNAPSHOT")) snapshotsRepoUrl else releasesRepoUrl 97 | } 98 | } 99 | } 100 | 101 | nexusPublishing { 102 | connectTimeout = Duration.ofMinutes(10) 103 | clientTimeout = Duration.ofMinutes(10) 104 | repositories { 105 | sonatype { 106 | username.set(System.getenv("SONATYPE_USERNAME")) 107 | password.set(System.getenv("SONATYPE_PASSWORD")) 108 | } 109 | } 110 | transitionCheckOptions { 111 | maxRetries.set(30) 112 | delayBetween.set(Duration.ofSeconds(45)) 113 | } 114 | } 115 | 116 | if (System.getenv("GPG_KEY_ID") != null) { 117 | signing { 118 | useInMemoryPgpKeys( 119 | System.getenv("GPG_KEY_ID"), 120 | System.getenv("GPG_PRIVATE_KEY"), 121 | System.getenv("GPG_PRIVATE_KEY_PASSWORD") 122 | ) 123 | sign(publishing.publications) 124 | } 125 | } 126 | -------------------------------------------------------------------------------- /gradle/libs.versions.toml: -------------------------------------------------------------------------------- 1 | [versions] 2 | curator = "5.7.0" 3 | junit = "5.12.2" 4 | testcontainers = "1.20.1" 5 | awaitility = "4.2.1" 6 | zookeeper = "3.9.2" 7 | 8 | [libraries] 9 | curator-recipes = { module = "org.apache.curator:curator-recipes", version.ref = "curator" } 10 | curator-framework = { module = "org.apache.curator:curator-framework", version.ref = "curator" } 11 | junit = { module = "org.junit:junit-bom", version.ref = "junit" } 12 | awaitility = { module = "org.awaitility:awaitility", version.ref = "awaitility" } 13 | testcontainers = { module = "org.testcontainers:testcontainers-bom", version.ref = "testcontainers" } 14 | zookeeper = { module = "org.apache.zookeeper:zookeeper", version.ref = "zookeeper" } 15 | 16 | [bundles] 17 | curator = ["curator-recipes", "curator-framework"] 18 | 19 | [plugins] 20 | springBoot = { id = "org.springframework.boot", version = "3.4.4" } 21 | springDependencyManagement = { id = "io.spring.dependency-management", version = "1.1.7" } 22 | axionRelease = { id = "pl.allegro.tech.build.axion-release", version = "1.18.3" } 23 | nexusPublish = { id = "io.github.gradle-nexus.publish-plugin", version = "2.0.0" } 24 | -------------------------------------------------------------------------------- /gradle/wrapper/gradle-wrapper.jar: -------------------------------------------------------------------------------- https://raw.githubusercontent.com/allegro/leader-only-spring-boot-starter/c59eb706e10237bf5cd2b857ec7f6bcecd105290/gradle/wrapper/gradle-wrapper.jar -------------------------------------------------------------------------------- /gradle/wrapper/gradle-wrapper.properties: -------------------------------------------------------------------------------- 1 | distributionBase=GRADLE_USER_HOME 2 | distributionPath=wrapper/dists 3 | distributionUrl=https\://services.gradle.org/distributions/gradle-8.14-bin.zip 4 | networkTimeout=10000 5 | validateDistributionUrl=true 6 | zipStoreBase=GRADLE_USER_HOME 7 | zipStorePath=wrapper/dists 8 | -------------------------------------------------------------------------------- /gradlew: -------------------------------------------------------------------------------- 1 | #!/bin/sh 2 | 3 | # 4 | # Copyright © 2015-2021 the original authors. 5 | # 6 | # Licensed under the Apache License, Version 2.0 (the "License"); 7 | # you may not use this file except in compliance with the License. 8 | # You may obtain a copy of the License at 9 | # 10 | # https://www.apache.org/licenses/LICENSE-2.0 11 | # 12 | # Unless required by applicable law or agreed to in writing, software 13 | # distributed under the License is distributed on an "AS IS" BASIS, 14 | # WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 15 | # See the License for the specific language governing permissions and 16 | # limitations under the License. 17 | # 18 | # SPDX-License-Identifier: Apache-2.0 19 | # 20 | 21 | ############################################################################## 22 | # 23 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If your /bin/sh is 28 | # noncompliant, but you have some other compliant shell such as ksh or 29 | # bash, then to run this script, type that shell name before the whole 30 | # command line, like: 31 | # 32 | # ksh Gradle 33 | # 34 | # Busybox and similar reduced shells will NOT work, because this script 35 | # requires all of these POSIX shell features: 36 | # * functions; 37 | # * expansions «$var», «${var}», «${var:-default}», «${var+SET}», 38 | # «${var#prefix}», «${var%suffix}», and «$( cmd )»; 39 | # * compound commands having a testable exit status, especially «case»; 40 | # * various built-in commands including «command», «set», and «ulimit». 41 | # 42 | # Important for patching: 43 | # 44 | # (2) This script targets any POSIX shell, so it avoids extensions provided 45 | # by Bash, Ksh, etc; in particular arrays are avoided. 46 | # 47 | # The "traditional" practice of packing multiple parameters into a 48 | # space-separated string is a well documented source of bugs and security 49 | # problems, so this is (mostly) avoided, by progressively accumulating 50 | # options in "$@", and eventually passing that to Java. 51 | # 52 | # Where the inherited environment variables (DEFAULT_JVM_OPTS, JAVA_OPTS, 53 | # and GRADLE_OPTS) rely on word-splitting, this is performed explicitly; 54 | # see the in-line comments for details. 55 | # 56 | # There are tweaks for specific operating systems such as AIX, CygWin, 57 | # Darwin, MinGW, and NonStop. 58 | # 59 | # (3) This script is generated from the Groovy template 60 | # https://github.com/gradle/gradle/blob/HEAD/platforms/jvm/plugins-application/src/main/resources/org/gradle/api/internal/plugins/unixStartScript.txt 61 | # within the Gradle project. 62 | # 63 | # You can find Gradle at https://github.com/gradle/gradle/. 64 | # 65 | ############################################################################## 66 | 67 | # Attempt to set APP_HOME 68 | 69 | # Resolve links: $0 may be a link 70 | app_path=$0 71 | 72 | # Need this for daisy-chained symlinks. 73 | while 74 | APP_HOME=${app_path%"${app_path##*/}"} # leaves a trailing /; empty if no leading path 75 | [ -h "$app_path" ] 76 | do 77 | ls=$( ls -ld "$app_path" ) 78 | link=${ls#*' -> '} 79 | case $link in #( 80 | /*) app_path=$link ;; #( 81 | *) app_path=$APP_HOME$link ;; 82 | esac 83 | done 84 | 85 | # This is normally unused 86 | # shellcheck disable=SC2034 87 | APP_BASE_NAME=${0##*/} 88 | # Discard cd standard output in case $CDPATH is set (https://github.com/gradle/gradle/issues/25036) 89 | APP_HOME=$( cd -P "${APP_HOME:-./}" > /dev/null && printf '%s\n' "$PWD" ) || exit 90 | 91 | # Use the maximum available, or set MAX_FD != -1 to use that value. 92 | MAX_FD=maximum 93 | 94 | warn () { 95 | echo "$*" 96 | } >&2 97 | 98 | die () { 99 | echo 100 | echo "$*" 101 | echo 102 | exit 1 103 | } >&2 104 | 105 | # OS specific support (must be 'true' or 'false'). 106 | cygwin=false 107 | msys=false 108 | darwin=false 109 | nonstop=false 110 | case "$( uname )" in #( 111 | CYGWIN* ) cygwin=true ;; #( 112 | Darwin* ) darwin=true ;; #( 113 | MSYS* | MINGW* ) msys=true ;; #( 114 | NONSTOP* ) nonstop=true ;; 115 | esac 116 | 117 | CLASSPATH="\\\"\\\"" 118 | 119 | 120 | # Determine the Java command to use to start the JVM. 121 | if [ -n "$JAVA_HOME" ] ; then 122 | if [ -x "$JAVA_HOME/jre/sh/java" ] ; then 123 | # IBM's JDK on AIX uses strange locations for the executables 124 | JAVACMD=$JAVA_HOME/jre/sh/java 125 | else 126 | JAVACMD=$JAVA_HOME/bin/java 127 | fi 128 | if [ ! -x "$JAVACMD" ] ; then 129 | die "ERROR: JAVA_HOME is set to an invalid directory: $JAVA_HOME 130 | 131 | Please set the JAVA_HOME variable in your environment to match the 132 | location of your Java installation." 133 | fi 134 | else 135 | JAVACMD=java 136 | if ! command -v java >/dev/null 2>&1 137 | then 138 | die "ERROR: JAVA_HOME is not set and no 'java' command could be found in your PATH. 139 | 140 | Please set the JAVA_HOME variable in your environment to match the 141 | location of your Java installation." 142 | fi 143 | fi 144 | 145 | # Increase the maximum file descriptors if we can. 146 | if ! "$cygwin" && ! "$darwin" && ! "$nonstop" ; then 147 | case $MAX_FD in #( 148 | max*) 149 | # In POSIX sh, ulimit -H is undefined. That's why the result is checked to see if it worked. 150 | # shellcheck disable=SC2039,SC3045 151 | MAX_FD=$( ulimit -H -n ) || 152 | warn "Could not query maximum file descriptor limit" 153 | esac 154 | case $MAX_FD in #( 155 | '' | soft) :;; #( 156 | *) 157 | # In POSIX sh, ulimit -n is undefined. That's why the result is checked to see if it worked. 158 | # shellcheck disable=SC2039,SC3045 159 | ulimit -n "$MAX_FD" || 160 | warn "Could not set maximum file descriptor limit to $MAX_FD" 161 | esac 162 | fi 163 | 164 | # Collect all arguments for the java command, stacking in reverse order: 165 | # * args from the command line 166 | # * the main class name 167 | # * -classpath 168 | # * -D...appname settings 169 | # * --module-path (only if needed) 170 | # * DEFAULT_JVM_OPTS, JAVA_OPTS, and GRADLE_OPTS environment variables. 171 | 172 | # For Cygwin or MSYS, switch paths to Windows format before running java 173 | if "$cygwin" || "$msys" ; then 174 | APP_HOME=$( cygpath --path --mixed "$APP_HOME" ) 175 | CLASSPATH=$( cygpath --path --mixed "$CLASSPATH" ) 176 | 177 | JAVACMD=$( cygpath --unix "$JAVACMD" ) 178 | 179 | # Now convert the arguments - kludge to limit ourselves to /bin/sh 180 | for arg do 181 | if 182 | case $arg in #( 183 | -*) false ;; # don't mess with options #( 184 | /?*) t=${arg#/} t=/${t%%/*} # looks like a POSIX filepath 185 | [ -e "$t" ] ;; #( 186 | *) false ;; 187 | esac 188 | then 189 | arg=$( cygpath --path --ignore --mixed "$arg" ) 190 | fi 191 | # Roll the args list around exactly as many times as the number of 192 | # args, so each arg winds up back in the position where it started, but 193 | # possibly modified. 194 | # 195 | # NB: a `for` loop captures its iteration list before it begins, so 196 | # changing the positional parameters here affects neither the number of 197 | # iterations, nor the values presented in `arg`. 198 | shift # remove old arg 199 | set -- "$@" "$arg" # push replacement arg 200 | done 201 | fi 202 | 203 | 204 | # Add default JVM options here. You can also use JAVA_OPTS and GRADLE_OPTS to pass JVM options to this script. 205 | DEFAULT_JVM_OPTS='"-Xmx64m" "-Xms64m"' 206 | 207 | # Collect all arguments for the java command: 208 | # * DEFAULT_JVM_OPTS, JAVA_OPTS, and optsEnvironmentVar are not allowed to contain shell fragments, 209 | # and any embedded shellness will be escaped. 210 | # * For example: A user cannot expect ${Hostname} to be expanded, as it is an environment variable and will be 211 | # treated as '${Hostname}' itself on the command line. 212 | 213 | set -- \ 214 | "-Dorg.gradle.appname=$APP_BASE_NAME" \ 215 | -classpath "$CLASSPATH" \ 216 | -jar "$APP_HOME/gradle/wrapper/gradle-wrapper.jar" \ 217 | "$@" 218 | 219 | # Stop when "xargs" is not available. 220 | if ! command -v xargs >/dev/null 2>&1 221 | then 222 | die "xargs is not available" 223 | fi 224 | 225 | # Use "xargs" to parse quoted args. 226 | # 227 | # With -n1 it outputs one arg per line, with the quotes and backslashes removed. 228 | # 229 | # In Bash we could simply go: 230 | # 231 | # readarray ARGS < <( xargs -n1 <<<"$var" ) && 232 | # set -- "${ARGS[@]}" "$@" 233 | # 234 | # but POSIX shell has neither arrays nor command substitution, so instead we 235 | # post-process each arg (as a line of input to sed) to backslash-escape any 236 | # character that might be a shell metacharacter, then use eval to reverse 237 | # that process (while maintaining the separation between arguments), and wrap 238 | # the whole thing up as a single "set" statement. 239 | # 240 | # This will of course break if any of these variables contains a newline or 241 | # an unmatched quote. 242 | # 243 | 244 | eval "set -- $( 245 | printf '%s\n' "$DEFAULT_JVM_OPTS $JAVA_OPTS $GRADLE_OPTS" | 246 | xargs -n1 | 247 | sed ' s~[^-[:alnum:]+,./:=@_]~\\&~g; ' | 248 | tr '\n' ' ' 249 | )" '"$@"' 250 | 251 | exec "$JAVACMD" "$@" 252 | -------------------------------------------------------------------------------- /gradlew.bat: -------------------------------------------------------------------------------- 1 | @rem 2 | @rem Copyright 2015 the original author or authors. 3 | @rem 4 | @rem Licensed under the Apache License, Version 2.0 (the "License"); 5 | @rem you may not use this file except in compliance with the License. 6 | @rem You may obtain a copy of the License at 7 | @rem 8 | @rem https://www.apache.org/licenses/LICENSE-2.0 9 | @rem 10 | @rem Unless required by applicable law or agreed to in writing, software 11 | @rem distributed under the License is distributed on an "AS IS" BASIS, 12 | @rem WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 13 | @rem See the License for the specific language governing permissions and 14 | @rem limitations under the License. 15 | @rem 16 | @rem SPDX-License-Identifier: Apache-2.0 17 | @rem 18 | 19 | @if "%DEBUG%"=="" @echo off 20 | @rem ########################################################################## 21 | @rem 22 | @rem Gradle startup script for Windows 23 | @rem 24 | @rem ########################################################################## 25 | 26 | @rem Set local scope for the variables with windows NT shell 27 | if "%OS%"=="Windows_NT" setlocal 28 | 29 | set DIRNAME=%~dp0 30 | if "%DIRNAME%"=="" set DIRNAME=. 31 | @rem This is normally unused 32 | set APP_BASE_NAME=%~n0 33 | set APP_HOME=%DIRNAME% 34 | 35 | @rem Resolve any "." and ".." in APP_HOME to make it shorter. 36 | for %%i in ("%APP_HOME%") do set APP_HOME=%%~fi 37 | 38 | @rem Add default JVM options here. You can also use JAVA_OPTS and GRADLE_OPTS to pass JVM options to this script. 39 | set DEFAULT_JVM_OPTS="-Xmx64m" "-Xms64m" 40 | 41 | @rem Find java.exe 42 | if defined JAVA_HOME goto findJavaFromJavaHome 43 | 44 | set JAVA_EXE=java.exe 45 | %JAVA_EXE% -version >NUL 2>&1 46 | if %ERRORLEVEL% equ 0 goto execute 47 | 48 | echo. 1>&2 49 | echo ERROR: JAVA_HOME is not set and no 'java' command could be found in your PATH. 1>&2 50 | echo. 1>&2 51 | echo Please set the JAVA_HOME variable in your environment to match the 1>&2 52 | echo location of your Java installation. 1>&2 53 | 54 | goto fail 55 | 56 | :findJavaFromJavaHome 57 | set JAVA_HOME=%JAVA_HOME:"=% 58 | set JAVA_EXE=%JAVA_HOME%/bin/java.exe 59 | 60 | if exist "%JAVA_EXE%" goto execute 61 | 62 | echo. 1>&2 63 | echo ERROR: JAVA_HOME is set to an invalid directory: %JAVA_HOME% 1>&2 64 | echo. 1>&2 65 | echo Please set the JAVA_HOME variable in your environment to match the 1>&2 66 | echo location of your Java installation. 1>&2 67 | 68 | goto fail 69 | 70 | :execute 71 | @rem Setup the command line 72 | 73 | set CLASSPATH= 74 | 75 | 76 | @rem Execute Gradle 77 | "%JAVA_EXE%" %DEFAULT_JVM_OPTS% %JAVA_OPTS% %GRADLE_OPTS% "-Dorg.gradle.appname=%APP_BASE_NAME%" -classpath "%CLASSPATH%" -jar "%APP_HOME%\gradle\wrapper\gradle-wrapper.jar" %* 78 | 79 | :end 80 | @rem End local scope for the variables with windows NT shell 81 | if %ERRORLEVEL% equ 0 goto mainEnd 82 | 83 | :fail 84 | rem Set variable GRADLE_EXIT_CONSOLE if you need the _script_ return code instead of 85 | rem the _cmd.exe /c_ return code! 86 | set EXIT_CODE=%ERRORLEVEL% 87 | if %EXIT_CODE% equ 0 set EXIT_CODE=1 88 | if not ""=="%GRADLE_EXIT_CONSOLE%" exit %EXIT_CODE% 89 | exit /b %EXIT_CODE% 90 | 91 | :mainEnd 92 | if "%OS%"=="Windows_NT" endlocal 93 | 94 | :omega 95 | -------------------------------------------------------------------------------- /settings.gradle.kts: -------------------------------------------------------------------------------- 1 | //plugins { 2 | // /** 3 | // * This plugin allows gradle to download requested JDK version 4 | // * @see https://docs.gradle.org/current/userguide/toolchains.html#sub:download_repositories 5 | // */ 6 | // id "org.gradle.toolchains.foojay-resolver-convention" version "0.7.0" 7 | //} 8 | 9 | rootProject.name = "leader-only-spring-boot-starter" 10 | 11 | -------------------------------------------------------------------------------- /src/main/java/pl/allegro/tech/boot/leader/only/LeaderOnlyBeanPostProcessor.java: -------------------------------------------------------------------------------- 1 | package pl.allegro.tech.boot.leader.only; 2 | 3 | import org.springframework.beans.factory.config.BeanPostProcessor; 4 | import org.springframework.lang.Nullable; 5 | import pl.allegro.tech.boot.leader.only.api.Leader; 6 | 7 | import static org.springframework.core.annotation.AnnotationUtils.findAnnotation; 8 | 9 | final class LeaderOnlyBeanPostProcessor implements BeanPostProcessor { 10 | 11 | private final LeadershipProxyFactory leadershipProxyFactory; 12 | 13 | public LeaderOnlyBeanPostProcessor(LeadershipProxyFactory leadershipProxyFactory) { 14 | this.leadershipProxyFactory = leadershipProxyFactory; 15 | } 16 | 17 | @Override 18 | public Object postProcessAfterInitialization(Object bean, @Nullable String beanName) { 19 | Leader annotation = findAnnotation(bean.getClass(), Leader.class); 20 | 21 | if (annotation == null) { 22 | return bean; 23 | } 24 | 25 | return leadershipProxyFactory.getProxy(bean, annotation.value()); 26 | } 27 | } -------------------------------------------------------------------------------- /src/main/java/pl/allegro/tech/boot/leader/only/LeaderOnlyConfiguration.java: -------------------------------------------------------------------------------- 1 | package pl.allegro.tech.boot.leader.only; 2 | 3 | import org.springframework.boot.autoconfigure.AutoConfiguration; 4 | import org.springframework.boot.autoconfigure.condition.ConditionalOnBean; 5 | import org.springframework.context.annotation.Bean; 6 | import org.springframework.context.annotation.Configuration; 7 | import pl.allegro.tech.boot.leader.only.api.LeadershipFactory; 8 | 9 | @AutoConfiguration 10 | public class LeaderOnlyConfiguration { 11 | @Bean 12 | LeadershipProxyFactory leaderOnlyProxyFactory(LeadershipFactory leadershipFactory) { 13 | return new LeadershipProxyFactory(leadershipFactory); 14 | } 15 | 16 | @Bean 17 | @ConditionalOnBean(LeadershipProxyFactory.class) 18 | LeaderOnlyBeanPostProcessor leaderOnlyBeanPostProcessor(LeadershipProxyFactory leadershipProxyFactory) { 19 | return new LeaderOnlyBeanPostProcessor(leadershipProxyFactory); 20 | } 21 | } 22 | -------------------------------------------------------------------------------- /src/main/java/pl/allegro/tech/boot/leader/only/LeadershipProxyFactory.java: -------------------------------------------------------------------------------- 1 | package pl.allegro.tech.boot.leader.only; 2 | 3 | import org.aopalliance.intercept.MethodInterceptor; 4 | import org.aopalliance.intercept.MethodInvocation; 5 | import org.slf4j.Logger; 6 | import org.springframework.aop.framework.ProxyFactory; 7 | import org.springframework.lang.NonNull; 8 | import pl.allegro.tech.boot.leader.only.api.LeaderOnly; 9 | import pl.allegro.tech.boot.leader.only.api.Leadership; 10 | import pl.allegro.tech.boot.leader.only.api.LeadershipAcquisitionCallback; 11 | import pl.allegro.tech.boot.leader.only.api.LeadershipFactory; 12 | import pl.allegro.tech.boot.leader.only.api.LeadershipLossCallback; 13 | 14 | import java.io.Closeable; 15 | 16 | import static org.slf4j.LoggerFactory.getLogger; 17 | import static org.springframework.core.annotation.AnnotationUtils.findAnnotation; 18 | 19 | final class LeadershipProxyFactory { 20 | private static final Logger logger = getLogger(LeadershipProxyFactory.class); 21 | 22 | private final LeadershipFactory leadershipFactory; 23 | 24 | LeadershipProxyFactory(LeadershipFactory leadershipFactory) { 25 | this.leadershipFactory = leadershipFactory; 26 | } 27 | 28 | @SuppressWarnings("unchecked") 29 | T getProxy(@NonNull T object, @NonNull String path) { 30 | Leadership leadership = leadershipFactory.of(path); 31 | initializeCallbacks(object, leadership); 32 | return (T) createProxy(object, leadership).getProxy(); 33 | } 34 | 35 | private void initializeCallbacks(@NonNull T object, @NonNull Leadership leadership) { 36 | String canonicalName = object.getClass().getCanonicalName(); 37 | if (object instanceof LeadershipAcquisitionCallback) { 38 | leadership.registerLeadershipAcquisitionCallback(() -> 39 | ((LeadershipAcquisitionCallback)object).onLeadershipAcquisition()); 40 | logger.info("{} registered as leadership acquisition callback", canonicalName); 41 | } 42 | if (object instanceof LeadershipLossCallback) { 43 | leadership.registerLeadershipLossCallback(() -> 44 | ((LeadershipLossCallback)object).onLeadershipLoss()); 45 | logger.info("{} registered as leadership loss callback", canonicalName); 46 | } 47 | } 48 | 49 | private ProxyFactory createProxy(@NonNull T object, @NonNull Leadership leadership) { 50 | ProxyFactory proxyFactory = new ProxyFactory(); 51 | proxyFactory.setTargetClass(object.getClass()); 52 | proxyFactory.setProxyTargetClass(true); 53 | proxyFactory.setTarget(object); 54 | proxyFactory.addAdvice(new LeaderOnlyMethodInterceptor(leadership)); 55 | proxyFactory.addInterface(Closeable.class); 56 | return proxyFactory; 57 | } 58 | 59 | private static final class LeaderOnlyMethodInterceptor implements MethodInterceptor { 60 | private final Leadership leadership; 61 | 62 | public LeaderOnlyMethodInterceptor(Leadership leadership) { 63 | this.leadership = leadership; 64 | } 65 | 66 | @Override 67 | public Object invoke(MethodInvocation invocation) throws Throwable { 68 | LeaderOnly annotation = findAnnotation(invocation.getMethod(), LeaderOnly.class); 69 | 70 | if (annotation != null) { 71 | if (leadership.hasLeadership()) { 72 | return invocation.proceed(); 73 | } 74 | 75 | return null; 76 | } else { 77 | return invocation.proceed(); 78 | } 79 | } 80 | } 81 | } 82 | -------------------------------------------------------------------------------- /src/main/java/pl/allegro/tech/boot/leader/only/api/ConnectionStringCannotBeEmptyException.java: -------------------------------------------------------------------------------- 1 | package pl.allegro.tech.boot.leader.only.api; 2 | 3 | /** 4 | * Thrown when connection string is empty. 5 | */ 6 | public final class ConnectionStringCannotBeEmptyException extends IllegalArgumentException { 7 | /** 8 | * Creates new instance of {@link ConnectionStringCannotBeEmptyException}. 9 | */ 10 | public ConnectionStringCannotBeEmptyException() { 11 | super("Provided connection string cannot be empty"); 12 | } 13 | } 14 | -------------------------------------------------------------------------------- /src/main/java/pl/allegro/tech/boot/leader/only/api/CuratorLeadershipCustomizer.java: -------------------------------------------------------------------------------- 1 | package pl.allegro.tech.boot.leader.only.api; 2 | 3 | import org.apache.curator.framework.CuratorFrameworkFactory; 4 | 5 | /** 6 | * Customizer for CuratorFrameworkFactory.Builder 7 | */ 8 | public interface CuratorLeadershipCustomizer { 9 | /** 10 | * Customize CuratorFrameworkFactory.Builder 11 | * 12 | * @param builder CuratorFrameworkFactory.Builder 13 | */ 14 | void customize(CuratorFrameworkFactory.Builder builder); 15 | } 16 | -------------------------------------------------------------------------------- /src/main/java/pl/allegro/tech/boot/leader/only/api/Leader.java: -------------------------------------------------------------------------------- 1 | package pl.allegro.tech.boot.leader.only.api; 2 | 3 | import org.springframework.stereotype.Component; 4 | 5 | import java.lang.annotation.ElementType; 6 | import java.lang.annotation.Retention; 7 | import java.lang.annotation.RetentionPolicy; 8 | import java.lang.annotation.Target; 9 | 10 | /** 11 | * Leader annotation. 12 | */ 13 | @Component 14 | @Target(ElementType.TYPE) 15 | @Retention(RetentionPolicy.RUNTIME) 16 | public @interface Leader { 17 | /** @return leader name */ 18 | String value(); 19 | } 20 | -------------------------------------------------------------------------------- /src/main/java/pl/allegro/tech/boot/leader/only/api/LeaderLatchCannotStartException.java: -------------------------------------------------------------------------------- 1 | package pl.allegro.tech.boot.leader.only.api; 2 | 3 | public class LeaderLatchCannotStartException extends IllegalStateException { 4 | public LeaderLatchCannotStartException(Exception e) { 5 | super("Cannot start LeaderLatch", e); 6 | } 7 | 8 | public LeaderLatchCannotStartException() { 9 | super("Cannot start LeaderLatch due timeout"); 10 | } 11 | } 12 | -------------------------------------------------------------------------------- /src/main/java/pl/allegro/tech/boot/leader/only/api/LeaderLatchCannotStopException.java: -------------------------------------------------------------------------------- 1 | package pl.allegro.tech.boot.leader.only.api; 2 | 3 | public class LeaderLatchCannotStopException extends IllegalStateException { 4 | public LeaderLatchCannotStopException(Exception e) { 5 | super("Cannot stop LeaderLatch", e); 6 | } 7 | } 8 | -------------------------------------------------------------------------------- /src/main/java/pl/allegro/tech/boot/leader/only/api/LeaderOnly.java: -------------------------------------------------------------------------------- 1 | package pl.allegro.tech.boot.leader.only.api; 2 | 3 | import java.lang.annotation.ElementType; 4 | import java.lang.annotation.Retention; 5 | import java.lang.annotation.RetentionPolicy; 6 | import java.lang.annotation.Target; 7 | 8 | @Target(ElementType.METHOD) 9 | @Retention(RetentionPolicy.RUNTIME) 10 | public @interface LeaderOnly { 11 | } -------------------------------------------------------------------------------- /src/main/java/pl/allegro/tech/boot/leader/only/api/Leadership.java: -------------------------------------------------------------------------------- 1 | package pl.allegro.tech.boot.leader.only.api; 2 | 3 | public interface Leadership { 4 | boolean hasLeadership(); 5 | 6 | void registerLeadershipAcquisitionCallback(Runnable runnable); 7 | 8 | void registerLeadershipLossCallback(Runnable runnable); 9 | } 10 | -------------------------------------------------------------------------------- /src/main/java/pl/allegro/tech/boot/leader/only/api/LeadershipAcquisitionCallback.java: -------------------------------------------------------------------------------- 1 | package pl.allegro.tech.boot.leader.only.api; 2 | 3 | public interface LeadershipAcquisitionCallback { 4 | 5 | void onLeadershipAcquisition(); 6 | 7 | } 8 | -------------------------------------------------------------------------------- /src/main/java/pl/allegro/tech/boot/leader/only/api/LeadershipChangeCallbacks.java: -------------------------------------------------------------------------------- 1 | package pl.allegro.tech.boot.leader.only.api; 2 | 3 | public interface LeadershipChangeCallbacks extends LeadershipAcquisitionCallback, LeadershipLossCallback { 4 | } 5 | -------------------------------------------------------------------------------- /src/main/java/pl/allegro/tech/boot/leader/only/api/LeadershipFactory.java: -------------------------------------------------------------------------------- 1 | package pl.allegro.tech.boot.leader.only.api; 2 | 3 | import org.springframework.lang.NonNull; 4 | 5 | public interface LeadershipFactory { 6 | Leadership of(@NonNull String path); 7 | } 8 | -------------------------------------------------------------------------------- /src/main/java/pl/allegro/tech/boot/leader/only/api/LeadershipLossCallback.java: -------------------------------------------------------------------------------- 1 | package pl.allegro.tech.boot.leader.only.api; 2 | 3 | public interface LeadershipLossCallback { 4 | 5 | void onLeadershipLoss(); 6 | 7 | } 8 | -------------------------------------------------------------------------------- /src/main/java/pl/allegro/tech/boot/leader/only/curator/ConnectionStringConverter.java: -------------------------------------------------------------------------------- 1 | package pl.allegro.tech.boot.leader.only.curator; 2 | 3 | import org.springframework.boot.context.properties.ConfigurationPropertiesBinding; 4 | import org.springframework.core.convert.converter.Converter; 5 | import org.springframework.lang.NonNull; 6 | import org.springframework.lang.Nullable; 7 | import org.springframework.util.StringUtils; 8 | import pl.allegro.tech.boot.leader.only.curator.CuratorLeadershipProperties.ConnectionString; 9 | 10 | @ConfigurationPropertiesBinding 11 | class ConnectionStringConverter implements Converter { 12 | @Nullable 13 | @Override 14 | public ConnectionString convert(@NonNull String source) { 15 | if (StringUtils.hasText(source)) { 16 | return new ConnectionString(source); 17 | } 18 | 19 | return null; 20 | } 21 | } 22 | -------------------------------------------------------------------------------- /src/main/java/pl/allegro/tech/boot/leader/only/curator/CuratorLeadership.java: -------------------------------------------------------------------------------- 1 | package pl.allegro.tech.boot.leader.only.curator; 2 | 3 | import org.apache.curator.framework.recipes.leader.LeaderLatch; 4 | import org.apache.curator.framework.recipes.leader.LeaderLatchListener; 5 | import org.slf4j.Logger; 6 | import pl.allegro.tech.boot.leader.only.api.LeaderLatchCannotStartException; 7 | import pl.allegro.tech.boot.leader.only.api.LeaderLatchCannotStopException; 8 | import pl.allegro.tech.boot.leader.only.api.Leadership; 9 | 10 | import java.io.Closeable; 11 | import java.io.IOException; 12 | import java.net.InetAddress; 13 | import java.net.UnknownHostException; 14 | import java.util.ArrayList; 15 | import java.util.List; 16 | import java.util.concurrent.ExecutorService; 17 | import java.util.concurrent.Executors; 18 | 19 | import static org.slf4j.LoggerFactory.getLogger; 20 | 21 | final class CuratorLeadership implements Leadership, Closeable { 22 | 23 | private static final Logger logger = getLogger(CuratorLeadership.class); 24 | 25 | private final LeaderLatch leaderLatch; 26 | private final List leadershipAcquisitionCallbacks = new ArrayList<>(); 27 | private final List leadershipLossCallbacks = new ArrayList<>(); 28 | private final ExecutorService callbacksExecutor = Executors.newSingleThreadExecutor(); 29 | 30 | public CuratorLeadership(String leaderLatchPath, LeaderLatch leaderLatch) { 31 | this.leaderLatch = leaderLatch; 32 | 33 | try { 34 | leaderLatch.start(); 35 | } catch (Exception e) { 36 | throw new LeaderLatchCannotStartException(e); 37 | } 38 | 39 | leaderLatch.addListener(new LeaderLatchListener() { 40 | final String hostname = resolveHostname(); 41 | 42 | @Override 43 | public void isLeader() { 44 | logger.info("{} is selected for the leader of {}", hostname, leaderLatchPath); 45 | leadershipAcquisitionCallbacks.forEach(callbacksExecutor::submit); 46 | logger.info("executed {} callback(s) on leadership acquisition of {} on {}", 47 | leadershipAcquisitionCallbacks.size(), leaderLatchPath, hostname); 48 | } 49 | 50 | @Override 51 | public void notLeader() { 52 | logger.info("{} is no longer the leader of {}", hostname, leaderLatchPath); 53 | leadershipLossCallbacks.forEach(callbacksExecutor::submit); 54 | logger.info("executed {} callback(s) on leadership loss of {} on {}", 55 | leadershipLossCallbacks.size(), leaderLatchPath, hostname); 56 | } 57 | 58 | private String resolveHostname() { 59 | try { 60 | return InetAddress.getLocalHost().getHostName(); 61 | } catch (UnknownHostException e) { 62 | return "???"; 63 | } 64 | } 65 | }); 66 | } 67 | 68 | @Override 69 | public boolean hasLeadership() { 70 | return leaderLatch.hasLeadership(); 71 | } 72 | 73 | @Override 74 | public void registerLeadershipAcquisitionCallback(Runnable callback) { 75 | leadershipAcquisitionCallbacks.add(callback); 76 | } 77 | 78 | @Override 79 | public void registerLeadershipLossCallback(Runnable callback) { 80 | leadershipLossCallbacks.add(callback); 81 | } 82 | 83 | @Override 84 | public void close() { 85 | try { 86 | leaderLatch.close(); 87 | } catch (IOException e) { 88 | throw new LeaderLatchCannotStopException(e); 89 | } 90 | } 91 | } 92 | -------------------------------------------------------------------------------- /src/main/java/pl/allegro/tech/boot/leader/only/curator/CuratorLeadershipConfiguration.java: -------------------------------------------------------------------------------- 1 | package pl.allegro.tech.boot.leader.only.curator; 2 | 3 | import org.apache.curator.drivers.TracerDriver; 4 | import org.apache.curator.ensemble.EnsembleProvider; 5 | import org.apache.curator.framework.CuratorFramework; 6 | import org.apache.curator.framework.CuratorFrameworkFactory; 7 | import org.springframework.boot.autoconfigure.AutoConfiguration; 8 | import org.springframework.boot.autoconfigure.AutoConfigureBefore; 9 | import org.springframework.boot.autoconfigure.condition.ConditionalOnBean; 10 | import org.springframework.boot.autoconfigure.condition.ConditionalOnProperty; 11 | import org.springframework.boot.context.properties.EnableConfigurationProperties; 12 | import org.springframework.context.annotation.Bean; 13 | import org.springframework.context.annotation.Configuration; 14 | import pl.allegro.tech.boot.leader.only.LeaderOnlyConfiguration; 15 | import pl.allegro.tech.boot.leader.only.api.CuratorLeadershipCustomizer; 16 | import pl.allegro.tech.boot.leader.only.api.LeadershipFactory; 17 | 18 | import java.util.Optional; 19 | import java.util.stream.Stream; 20 | 21 | import static org.apache.curator.framework.CuratorFrameworkFactory.builder; 22 | 23 | /** 24 | * Configuration for Curator based leadership. 25 | */ 26 | @AutoConfiguration 27 | @AutoConfigureBefore(LeaderOnlyConfiguration.class) 28 | @EnableConfigurationProperties(CuratorLeadershipProperties.class) 29 | public class CuratorLeadershipConfiguration { 30 | @Bean(initMethod = "start", destroyMethod = "close") 31 | @ConditionalOnProperty(prefix = "curator-leadership", name = "connection-string") 32 | CuratorFramework leaderOnlyCuratorClient( 33 | CuratorLeadershipProperties properties, 34 | Optional> optionalCuratorFrameworkCustomizerProvider, 35 | Optional optionalEnsembleProvider, 36 | Optional optionalTracerDriverProvider) { 37 | final CuratorFrameworkFactory.Builder builder = builder() 38 | .connectString(properties.getConnectionString()) 39 | .retryPolicy(properties.getRetryPolicy()); 40 | 41 | properties.getAuth() 42 | .ifPresent(auth -> builder.authorization(auth.getSchema(), auth.getCredentials())); 43 | 44 | properties.getSessionTimeoutMs() 45 | .ifPresent(builder::sessionTimeoutMs); 46 | 47 | properties.getConnectionTimeoutMs() 48 | .ifPresent(builder::connectionTimeoutMs); 49 | 50 | properties.getWaitForShutdownTimeoutMs() 51 | .ifPresent(builder::waitForShutdownTimeoutMs); 52 | 53 | builder.namespace(properties.getNamespace()); 54 | 55 | optionalEnsembleProvider.ifPresent(builder::ensembleProvider); 56 | 57 | optionalCuratorFrameworkCustomizerProvider 58 | .ifPresent(customizers -> customizers.forEach(it -> it.customize(builder))); 59 | 60 | final CuratorFramework client = builder.build(); 61 | 62 | optionalTracerDriverProvider 63 | .ifPresent(tracerDriver -> Optional.ofNullable(client.getZookeeperClient()) 64 | .ifPresent(zookeeperClient -> zookeeperClient.setTracerDriver(tracerDriver))); 65 | 66 | return client; 67 | } 68 | 69 | @Bean 70 | @ConditionalOnBean(name = "leaderOnlyCuratorClient") 71 | LeadershipFactory curatorLeaderLatchFactory(CuratorFramework leaderOnlyCuratorClient) { 72 | return new CuratorLeadershipFactoryImpl(leaderOnlyCuratorClient); 73 | } 74 | 75 | @Bean 76 | ConnectionStringConverter connectionStringConverter() { 77 | return new ConnectionStringConverter(); 78 | } 79 | } 80 | -------------------------------------------------------------------------------- /src/main/java/pl/allegro/tech/boot/leader/only/curator/CuratorLeadershipFactoryImpl.java: -------------------------------------------------------------------------------- 1 | package pl.allegro.tech.boot.leader.only.curator; 2 | 3 | import org.apache.curator.framework.CuratorFramework; 4 | import org.apache.curator.framework.recipes.leader.LeaderLatch; 5 | import org.springframework.lang.NonNull; 6 | import pl.allegro.tech.boot.leader.only.api.Leadership; 7 | import pl.allegro.tech.boot.leader.only.api.LeadershipFactory; 8 | 9 | import java.io.Closeable; 10 | import java.nio.file.Paths; 11 | import java.util.concurrent.ConcurrentHashMap; 12 | 13 | final class CuratorLeadershipFactoryImpl implements LeadershipFactory, Closeable { 14 | private static final String ABSOLUTE_PATH = "/"; 15 | 16 | private final ConcurrentHashMap leaderships = new ConcurrentHashMap<>(); 17 | 18 | private final CuratorFramework client; 19 | 20 | public CuratorLeadershipFactoryImpl(CuratorFramework client) { 21 | this.client = client; 22 | } 23 | 24 | @Override 25 | public Leadership of(@NonNull String path) { 26 | final String absolutePath = Paths.get(ABSOLUTE_PATH, path).toString(); 27 | if (!leaderships.containsKey(absolutePath)) { 28 | final LeaderLatch latch = new LeaderLatch(client, absolutePath, "", LeaderLatch.CloseMode.NOTIFY_LEADER); 29 | leaderships.put(absolutePath, new CuratorLeadership(absolutePath, latch)); 30 | } 31 | 32 | return leaderships.get(absolutePath); 33 | } 34 | 35 | @Override 36 | public void close() { 37 | leaderships.values().forEach(CuratorLeadership::close); 38 | } 39 | } 40 | -------------------------------------------------------------------------------- /src/main/java/pl/allegro/tech/boot/leader/only/curator/CuratorLeadershipProperties.java: -------------------------------------------------------------------------------- 1 | package pl.allegro.tech.boot.leader.only.curator; 2 | 3 | import org.apache.curator.RetryPolicy; 4 | import org.apache.curator.retry.ExponentialBackoffRetry; 5 | import org.apache.curator.retry.RetryOneTime; 6 | import org.springframework.boot.context.properties.ConfigurationProperties; 7 | import org.springframework.boot.convert.DurationUnit; 8 | import pl.allegro.tech.boot.leader.only.api.ConnectionStringCannotBeEmptyException; 9 | 10 | import java.nio.file.Path; 11 | import java.nio.file.Paths; 12 | import java.time.Duration; 13 | import java.util.Optional; 14 | 15 | import static java.time.temporal.ChronoUnit.MILLIS; 16 | import static org.springframework.util.StringUtils.hasText; 17 | 18 | @ConfigurationProperties(prefix = "curator-leadership") 19 | class CuratorLeadershipProperties { 20 | private static final Path DEFAULT_NAMESPACE = Paths.get("leader-only"); 21 | 22 | private final ConnectionString connectionString; 23 | private final RetryPolicyProperties retry; 24 | private final AuthProperties auth; 25 | private final TimeoutProperties timeout; 26 | private final Path namespace; 27 | 28 | public CuratorLeadershipProperties( 29 | ConnectionString connectionString, 30 | Path namespace, 31 | RetryPolicyProperties retry, 32 | AuthProperties auth, 33 | TimeoutProperties timeout 34 | ) { 35 | this.connectionString = connectionString; 36 | this.namespace = Optional.ofNullable(namespace) 37 | .orElse(DEFAULT_NAMESPACE); 38 | this.retry = retry; 39 | this.auth = auth; 40 | this.timeout = timeout; 41 | } 42 | 43 | public String getConnectionString() { 44 | return Optional.ofNullable(connectionString) 45 | .map(ConnectionString::getValue) 46 | .orElseThrow(ConnectionStringCannotBeEmptyException::new); 47 | } 48 | 49 | public String getNamespace() { 50 | return namespace.toString(); 51 | } 52 | 53 | public RetryPolicy getRetryPolicy() { 54 | return Optional.ofNullable(retry) 55 | .map(RetryPolicyProperties::getExponentialBackoffRetry) 56 | .orElseGet(() -> new RetryOneTime(100)); 57 | } 58 | 59 | public Optional getAuth() { 60 | return Optional.ofNullable(auth) 61 | .filter(AuthProperties::hasCredentials); 62 | } 63 | 64 | public Optional getSessionTimeoutMs() { 65 | return Optional.ofNullable(timeout) 66 | .map(TimeoutProperties::getSession) 67 | .map(Duration::toMillis) 68 | .map(Long::intValue); 69 | } 70 | 71 | public Optional getConnectionTimeoutMs() { 72 | return Optional.ofNullable(timeout) 73 | .map(TimeoutProperties::getConnection) 74 | .map(Duration::toMillis) 75 | .map(Long::intValue); 76 | } 77 | 78 | public Optional getWaitForShutdownTimeoutMs() { 79 | return Optional.ofNullable(timeout) 80 | .map(TimeoutProperties::getWaitForShutdown) 81 | .map(Duration::toMillis) 82 | .map(Long::intValue); 83 | } 84 | 85 | static class ConnectionString { 86 | private final String value; 87 | 88 | ConnectionString(String value) { 89 | this.value = value; 90 | } 91 | 92 | public String getValue() { 93 | return value; 94 | } 95 | } 96 | 97 | static class RetryPolicyProperties { 98 | private static final int DEFAULT_BASE_SLEEP_TIME_MS = 200; 99 | private static final int DEFAULT_MAX_SLEEP_TIME_MS = 1000; 100 | 101 | private final Integer maxRetries; 102 | private final Duration maxSleepTime; 103 | private final Duration baseSleepTime; 104 | 105 | RetryPolicyProperties(Integer maxRetries, Duration maxSleepTime, Duration baseSleepTime) { 106 | this.maxRetries = Optional.ofNullable(maxRetries).orElse(3); 107 | this.maxSleepTime = maxSleepTime; 108 | this.baseSleepTime = baseSleepTime; 109 | } 110 | 111 | public RetryPolicy getExponentialBackoffRetry() { 112 | return new ExponentialBackoffRetry(getBaseSleepTime(), maxRetries, getMaxSleepTime()); 113 | } 114 | 115 | private int getBaseSleepTime() { 116 | return Optional.ofNullable(baseSleepTime) 117 | .map(Duration::toMillis) 118 | .map(Long::intValue) 119 | .orElse(DEFAULT_BASE_SLEEP_TIME_MS); 120 | } 121 | 122 | private int getMaxSleepTime() { 123 | return Optional.ofNullable(maxSleepTime) 124 | .map(Duration::toMillis) 125 | .map(Long::intValue) 126 | .orElse(DEFAULT_MAX_SLEEP_TIME_MS); 127 | } 128 | } 129 | 130 | static class AuthProperties { 131 | private final String username; 132 | private final String password; 133 | private final String schema; 134 | 135 | AuthProperties(String username, String password, String schema) { 136 | this.username = username; 137 | this.password = password; 138 | this.schema = Optional.ofNullable(schema).orElse("digest"); 139 | } 140 | 141 | public String getSchema() { 142 | return schema; 143 | } 144 | 145 | private boolean hasCredentials() { 146 | return hasText(username) && hasText(password); 147 | } 148 | 149 | public byte[] getCredentials() { 150 | return (username + ":" + password).getBytes(); 151 | } 152 | } 153 | 154 | static class TimeoutProperties { 155 | @DurationUnit(MILLIS) 156 | private final Duration session; 157 | @DurationUnit(MILLIS) 158 | private final Duration connection; 159 | @DurationUnit(MILLIS) 160 | private final Duration waitForShutdown; 161 | 162 | TimeoutProperties(Duration session, Duration connection, Duration waitForShutdown) { 163 | this.session = session; 164 | this.connection = connection; 165 | this.waitForShutdown = waitForShutdown; 166 | } 167 | 168 | public Duration getSession() { 169 | return session; 170 | } 171 | 172 | public Duration getConnection() { 173 | return connection; 174 | } 175 | 176 | public Duration getWaitForShutdown() { 177 | return waitForShutdown; 178 | } 179 | } 180 | } 181 | -------------------------------------------------------------------------------- /src/main/resources/META-INF/spring/org.springframework.boot.autoconfigure.AutoConfiguration.imports: -------------------------------------------------------------------------------- 1 | pl.allegro.tech.boot.leader.only.LeaderOnlyConfiguration 2 | pl.allegro.tech.boot.leader.only.curator.CuratorLeadershipConfiguration 3 | -------------------------------------------------------------------------------- /src/test/java/pl/allegro/tech/boot/leader/only/api/LeaderChangeCallbacksTest.java: -------------------------------------------------------------------------------- 1 | package pl.allegro.tech.boot.leader.only.api; 2 | 3 | import org.junit.jupiter.api.AfterEach; 4 | import org.junit.jupiter.api.Test; 5 | import org.springframework.beans.factory.annotation.Autowired; 6 | import org.springframework.boot.test.context.SpringBootTest; 7 | import org.springframework.boot.test.context.TestConfiguration; 8 | import org.springframework.context.annotation.Bean; 9 | import org.springframework.context.annotation.Import; 10 | import pl.allegro.tech.boot.leader.only.fixtures.SampleApplication; 11 | import pl.allegro.tech.boot.leader.only.fixtures.SampleLeaderOnlyExecutor; 12 | 13 | import static org.junit.jupiter.api.Assertions.assertEquals; 14 | 15 | @SpringBootTest(classes = SampleApplication.class) 16 | @Import(LeaderChangeCallbacksTest.TestLeaderConfiguration.class) 17 | class LeaderChangeCallbacksTest { 18 | 19 | private static final TestLeadership TEST_LEADERSHIP = new TestLeadership(); 20 | 21 | @Autowired 22 | SampleLeaderOnlyExecutor underTest; 23 | 24 | @AfterEach 25 | public void cleanUp() { 26 | underTest.resetCounters(); 27 | } 28 | 29 | @Test 30 | void shouldExecuteLeadershipAcquisitionCallbackWhenSetAsLeader() { 31 | TEST_LEADERSHIP.setLeadership(true); 32 | 33 | int actual = underTest.getLeadershipAcquisitionCounter(); 34 | 35 | assertEquals(1, actual); 36 | } 37 | 38 | @Test 39 | void shouldNotExecuteLeadershipLossCallbackWhenSetAsLeader() { 40 | TEST_LEADERSHIP.setLeadership(true); 41 | 42 | int actual = underTest.getLeadershipLossCounter(); 43 | 44 | assertEquals(0, actual); 45 | } 46 | 47 | @Test 48 | void shouldExecuteLeadershipLossCallbackWhenSetAsNotLeader() { 49 | TEST_LEADERSHIP.setLeadership(false); 50 | 51 | int actual = underTest.getLeadershipLossCounter(); 52 | 53 | assertEquals(1, actual); 54 | } 55 | 56 | @Test 57 | void shouldNotExecuteLeadershipAcquisitionCallbackWhenSetAsNotLeader() { 58 | TEST_LEADERSHIP.setLeadership(false); 59 | 60 | int actual = underTest.getLeadershipAcquisitionCounter(); 61 | 62 | assertEquals(0, actual); 63 | } 64 | 65 | @TestConfiguration 66 | static class TestLeaderConfiguration { 67 | @Bean 68 | LeadershipFactory testLeadershipFactory() { 69 | return path -> TEST_LEADERSHIP; 70 | } 71 | } 72 | } 73 | -------------------------------------------------------------------------------- /src/test/java/pl/allegro/tech/boot/leader/only/api/LeaderOnlyTest.java: -------------------------------------------------------------------------------- 1 | package pl.allegro.tech.boot.leader.only.api; 2 | 3 | import org.junit.jupiter.api.Test; 4 | import org.junit.jupiter.params.ParameterizedTest; 5 | import org.junit.jupiter.params.provider.ValueSource; 6 | import org.springframework.beans.factory.annotation.Autowired; 7 | import org.springframework.boot.test.context.SpringBootTest; 8 | import org.springframework.boot.test.context.TestConfiguration; 9 | import org.springframework.context.annotation.Bean; 10 | import org.springframework.context.annotation.Import; 11 | import pl.allegro.tech.boot.leader.only.fixtures.SampleApplication; 12 | import pl.allegro.tech.boot.leader.only.fixtures.SampleLeaderOnlyExecutor; 13 | 14 | import static org.junit.jupiter.api.Assertions.assertEquals; 15 | import static org.junit.jupiter.api.Assertions.assertNull; 16 | 17 | @SpringBootTest(classes = SampleApplication.class) 18 | @Import(LeaderOnlyTest.TestLeaderConfiguration.class) 19 | class LeaderOnlyTest { 20 | 21 | private static final TestLeadership TEST_LEADERSHIP = new TestLeadership(); 22 | 23 | @Autowired 24 | SampleLeaderOnlyExecutor underTest; 25 | 26 | @Test 27 | void shouldRunOnlyOnLeaderIfMethodHasLeaderOnlyAnnotation() { 28 | TEST_LEADERSHIP.setLeadership(true); 29 | 30 | Integer actual = underTest.calculateWhatIsTwoPlusTwo(); 31 | 32 | assertEquals(4, actual); 33 | } 34 | 35 | @Test 36 | void shouldNotRunOnNotLeaderIfMethodHasLeaderOnlyAnnotation() { 37 | TEST_LEADERSHIP.setLeadership(false); 38 | 39 | Integer actual = underTest.calculateWhatIsTwoPlusTwo(); 40 | 41 | assertNull(actual); 42 | } 43 | 44 | @ParameterizedTest 45 | @ValueSource(booleans = {true, false}) 46 | void shouldRunRegardlessOfLeadershipIfMethodHasNoLeaderOnlyAnnotation(boolean leadership) { 47 | TEST_LEADERSHIP.setLeadership(leadership); 48 | 49 | Integer actual = underTest.calculateWhatIsOnePlusTwo(); 50 | 51 | assertEquals(3, actual); 52 | } 53 | 54 | @TestConfiguration 55 | static class TestLeaderConfiguration { 56 | @Bean 57 | LeadershipFactory testLeadershipFactory() { 58 | return path -> TEST_LEADERSHIP; 59 | } 60 | } 61 | } 62 | -------------------------------------------------------------------------------- /src/test/java/pl/allegro/tech/boot/leader/only/api/TestLeadership.java: -------------------------------------------------------------------------------- 1 | package pl.allegro.tech.boot.leader.only.api; 2 | 3 | import java.util.ArrayList; 4 | import java.util.List; 5 | 6 | class TestLeadership implements Leadership { 7 | private boolean leadership; 8 | private final List leadershipAcquisitionCallbacks = new ArrayList<>(); 9 | private final List leadershipLossCallbacks = new ArrayList<>(); 10 | 11 | @Override 12 | public boolean hasLeadership() { 13 | return leadership; 14 | } 15 | 16 | @Override 17 | public void registerLeadershipAcquisitionCallback(Runnable callback) { 18 | leadershipAcquisitionCallbacks.add(callback); 19 | } 20 | 21 | @Override 22 | public void registerLeadershipLossCallback(Runnable callback) { 23 | leadershipLossCallbacks.add(callback); 24 | } 25 | 26 | public void setLeadership(boolean leadership) { 27 | if (leadership) { 28 | leadershipAcquisitionCallbacks.forEach(Runnable::run); 29 | } else { 30 | leadershipLossCallbacks.forEach(Runnable::run); 31 | 32 | } 33 | this.leadership = leadership; 34 | } 35 | 36 | private boolean isLeadershipAcquired(boolean leadership) { 37 | return !this.leadership && leadership; 38 | } 39 | 40 | private boolean isLeadershipLost(boolean leadership) { 41 | return this.leadership && !leadership; 42 | } 43 | 44 | } 45 | -------------------------------------------------------------------------------- /src/test/java/pl/allegro/tech/boot/leader/only/curator/ConnectionStringConverterTest.java: -------------------------------------------------------------------------------- 1 | package pl.allegro.tech.boot.leader.only.curator; 2 | 3 | import org.junit.jupiter.params.ParameterizedTest; 4 | import org.junit.jupiter.params.provider.ValueSource; 5 | import pl.allegro.tech.boot.leader.only.curator.CuratorLeadershipProperties.ConnectionString; 6 | 7 | import static org.junit.jupiter.api.Assertions.assertEquals; 8 | import static org.junit.jupiter.api.Assertions.assertNotNull; 9 | import static org.junit.jupiter.api.Assertions.assertNull; 10 | 11 | class ConnectionStringConverterTest { 12 | 13 | private final ConnectionStringConverter underTest = new ConnectionStringConverter(); 14 | 15 | @ParameterizedTest 16 | @ValueSource(strings = {"localhost:2181", "127.0.0.1:3000,127.0.0.1:3001"}) 17 | void shouldConvertStringToConnectionString(String source) { 18 | // when 19 | final ConnectionString connectionString = underTest.convert(source); 20 | 21 | // then 22 | assertNotNull(connectionString); 23 | assertEquals(connectionString.getValue(), source); 24 | } 25 | 26 | @ParameterizedTest 27 | @ValueSource(strings = {"", " "}) 28 | void shouldNotConvertEmptyStringToConnectionString(String source) { 29 | // when 30 | final ConnectionString connectionString = underTest.convert(source); 31 | 32 | // then 33 | assertNull(connectionString); 34 | } 35 | } -------------------------------------------------------------------------------- /src/test/java/pl/allegro/tech/boot/leader/only/curator/CuratorLeadershipTest.java: -------------------------------------------------------------------------------- 1 | package pl.allegro.tech.boot.leader.only.curator; 2 | 3 | import org.junit.jupiter.api.Test; 4 | import org.springframework.beans.factory.annotation.Autowired; 5 | import org.springframework.boot.test.context.SpringBootTest; 6 | import org.springframework.test.context.DynamicPropertyRegistry; 7 | import org.springframework.test.context.DynamicPropertySource; 8 | import org.testcontainers.containers.GenericContainer; 9 | import org.testcontainers.junit.jupiter.Container; 10 | import org.testcontainers.junit.jupiter.Testcontainers; 11 | import org.testcontainers.utility.DockerImageName; 12 | import pl.allegro.tech.boot.leader.only.fixtures.SampleApplication; 13 | import pl.allegro.tech.boot.leader.only.fixtures.SampleLeaderOnlyExecutor; 14 | 15 | import static java.util.concurrent.TimeUnit.SECONDS; 16 | import static java.util.function.Predicate.isEqual; 17 | import static org.awaitility.Awaitility.await; 18 | import static org.junit.jupiter.api.Assertions.assertEquals; 19 | import static org.junit.jupiter.api.Assertions.assertTrue; 20 | 21 | @Testcontainers 22 | @SpringBootTest(classes = SampleApplication.class) 23 | class CuratorLeadershipTest { 24 | 25 | private static final int PORT = 2181; 26 | 27 | @Container 28 | public static final GenericContainer zookeeper = new GenericContainer<>(DockerImageName.parse("zookeeper:3.6.2")) 29 | .withExposedPorts(PORT); 30 | 31 | @DynamicPropertySource 32 | static void zookeeperProperties(DynamicPropertyRegistry registry) { 33 | registry.add("curator-leadership.connection-string", () -> 34 | zookeeper.getHost() + ":" + zookeeper.getMappedPort(PORT)); 35 | registry.add("curator-leadership.namespace", () -> "test/path"); 36 | } 37 | 38 | @Autowired 39 | SampleLeaderOnlyExecutor underTest; 40 | 41 | @Test 42 | void shouldRespondOnlyOnLeader() { 43 | assertTrue(zookeeper.isRunning()); 44 | 45 | await().atMost(5, SECONDS).until(() -> underTest.calculateWhatIsTwoPlusTwo(), isEqual(4)); 46 | 47 | assertEquals(1, underTest.getLeadershipAcquisitionCounter()); 48 | } 49 | } 50 | -------------------------------------------------------------------------------- /src/test/java/pl/allegro/tech/boot/leader/only/fixtures/SampleApplication.java: -------------------------------------------------------------------------------- 1 | package pl.allegro.tech.boot.leader.only.fixtures; 2 | 3 | import org.springframework.boot.autoconfigure.SpringBootApplication; 4 | 5 | @SpringBootApplication 6 | public class SampleApplication { 7 | } 8 | -------------------------------------------------------------------------------- /src/test/java/pl/allegro/tech/boot/leader/only/fixtures/SampleLeaderOnlyExecutor.java: -------------------------------------------------------------------------------- 1 | package pl.allegro.tech.boot.leader.only.fixtures; 2 | 3 | import pl.allegro.tech.boot.leader.only.api.Leader; 4 | import pl.allegro.tech.boot.leader.only.api.LeaderOnly; 5 | import pl.allegro.tech.boot.leader.only.api.LeadershipChangeCallbacks; 6 | 7 | @Leader("sample") 8 | public class SampleLeaderOnlyExecutor implements LeadershipChangeCallbacks { 9 | private int leadershipAcquisitionCounter = 0; 10 | private int leadershipLossCounter = 0; 11 | 12 | @LeaderOnly 13 | public Integer calculateWhatIsTwoPlusTwo() { 14 | return 4; 15 | } 16 | 17 | public void onLeadershipAcquisition() { 18 | leadershipAcquisitionCounter++; 19 | } 20 | 21 | public void onLeadershipLoss() { 22 | leadershipLossCounter++; 23 | } 24 | 25 | public Integer calculateWhatIsOnePlusTwo() { 26 | return 3; 27 | } 28 | 29 | public int getLeadershipAcquisitionCounter() { 30 | return leadershipAcquisitionCounter; 31 | } 32 | 33 | public int getLeadershipLossCounter() { 34 | return leadershipLossCounter; 35 | } 36 | 37 | public void resetCounters() { 38 | leadershipAcquisitionCounter = 0; 39 | leadershipLossCounter = 0; 40 | } 41 | } 42 | --------------------------------------------------------------------------------