├── doit2.sh
├── doit.sh
├── .gitignore
├── elnode-server.el
├── project.clj
├── README.md
├── src
    └── spawner
    │   └── core.clj
└── LICENSE


/doit2.sh:
--------------------------------------------------------------------------------
1 | #!/bin/bash
2 | 
3 | sleep 2
4 | echo "WAH!"
5 | exit 3
6 | 


--------------------------------------------------------------------------------
/doit.sh:
--------------------------------------------------------------------------------
1 | #!/bin/bash
2 | 
3 | for i in $(seq 1 8)
4 | do
5 |     date
6 |     sleep 1
7 |     echo "meh"
8 | done
9 | 


--------------------------------------------------------------------------------
/.gitignore:
--------------------------------------------------------------------------------
 1 | /target
 2 | /classes
 3 | /checkouts
 4 | pom.xml
 5 | pom.xml.asc
 6 | *.jar
 7 | *.class
 8 | /.lein-*
 9 | /.nrepl-port
10 | 


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/elnode-server.el:
--------------------------------------------------------------------------------
 1 | 
 2 | (require 'elnode)
 3 | 
 4 | (setq spawner/commands
 5 |       '((:start :doit2)
 6 |         (:status)))
 7 | 
 8 | (setq spawner/commands
 9 |       '((:status)))
10 | 
11 | (setq spawner/commands
12 |       '((:exit)))
13 | 
14 | (defun spawner-handler (httpcon)
15 |   (message "data: %S" (elnode-http-params httpcon))
16 |   (elnode-http-start httpcon 200 '(content-type "text/lisp"))
17 |   (elnode-http-return httpcon (format "%S" (pop spawner/commands))))
18 | 
19 | (elnode-start 'spawner-handler :port 6001)
20 | 


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/project.clj:
--------------------------------------------------------------------------------
 1 | (defproject spawner "0.1.0-SNAPSHOT"
 2 |   :description "FIXME: write description"
 3 |   :url "http://example.com/FIXME"
 4 |   :license {:name "Eclipse Public License"
 5 |             :url "http://www.eclipse.org/legal/epl-v10.html"}
 6 |   :dependencies [[org.clojure/clojure "1.6.0"]
 7 |                  [me.raynes/conch "0.8.0"]
 8 |                  [org.clojure/core.async "0.1.256.0-1bf8cf-alpha"]
 9 |                  [http-kit "2.1.6"]]
10 |   :main ^:skip-aot spawner.core
11 |   :target-path "target/%s"
12 |   :profiles {:uberjar {:aot :all}})
13 | 


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/README.md:
--------------------------------------------------------------------------------
 1 | # spawner
 2 | 
 3 | A process supervisor program in Clojure.
 4 | 
 5 | ## Installation
 6 | 
 7 | Install from github for now.
 8 | 
 9 | ## Usage
10 | 
11 | To run:
12 | 
13 |     $ java -jar spawner-0.1.0-standalone.jar [monitor-url]
14 | 
15 | ## Options
16 | 
17 | monitor-url is the HTTP address of a compliant monitoring daemon.
18 | 
19 | 
20 | ## Examples
21 | 
22 | This whole thing is really an example. Since the config for the files
23 | is baked in it's not really portable. That's ok I think (maybe). The
24 | point is the ease of the pattern.
25 | 
26 | ### Bugs
27 | 
28 | There are no bugs with this software at all.
29 | 
30 | 
31 | ## License
32 | 
33 | Copyright © 2014 N J Ferrier
34 | 
35 | Distributed under the Eclipse Public License either version 1.0 or (at
36 | your option) any later version.
37 | 


--------------------------------------------------------------------------------
/src/spawner/core.clj:
--------------------------------------------------------------------------------
  1 | (ns spawner.core
  2 |   "A spawning process controlller.
  3 | 
  4 | Like a process supervisor.  This uses core.async extensively."
  5 |   (:require
  6 |    [clojure.core.async
  7 |     :refer [>! <! >!! <!! go go-loop chan close!  alts! alts!! timeout thread]])
  8 |   (:require [clojure.string :as str])
  9 |   (:require [clojure.java.io :as io])
 10 |   (:require [org.httpkit.client :as http-kit])
 11 |   (:gen-class))
 12 | 
 13 | (def scripts
 14 |   "The list of scripts we'll start."
 15 |   { :doit ["bash" "doit.sh"]
 16 |    :doit2 ["bash" "doit2.sh"]})
 17 | 
 18 | (defn start-process
 19 |   "Start the process with script-defn." [id script-defn]
 20 |   (let [proc (.start (ProcessBuilder. script-defn))
 21 |         from (chan)
 22 |         to (chan)]
 23 |     ;; Make a thread to wait for the exit
 24 |     (thread (>!! from [:exit id (.waitFor proc)]))
 25 | 
 26 |     ;; Make a thread to read the inputstream ... 
 27 |     (thread
 28 |      (binding [*in* (io/reader (.getInputStream proc))]
 29 |        (loop [line (read-line)]
 30 |          (when line
 31 |            (>!! from [:line id line])
 32 |            (recur (read-line))))))
 33 | 
 34 |     ;; ... and another to process incomming messages.
 35 |     (thread
 36 |      ;; This might have to be changed, what if a blocked out-stream
 37 |      ;; stopped us getting a kill signal from the channel?
 38 |      (loop [[message arg] (<!! to)]
 39 |        (case message
 40 |          :line (binding [*out* (io/reader (.getOutputStream proc))] (println arg))
 41 |          :kill (.destroy proc))
 42 |        (recur (<!! to))))
 43 | 
 44 |     ;; Return the info
 45 |     { :from from :to to :id id :proc proc }))
 46 | 
 47 | (defn call-http
 48 |   "Call the monitor and report status.
 49 | 
 50 | HTTP requests are made to monitor-url and the response is returned to
 51 | the request-chan. Any message on the response-chan (presumably a
 52 | response to the last request) is sent in the next call."
 53 |   [monitor-url request-chan response-chan]
 54 |   (loop [[to-send ch] (alts!! [response-chan (timeout 500)])]
 55 |     (when (or (not to-send) (not (= to-send [:quit])))
 56 |       (http-kit/post
 57 |        monitor-url
 58 |        { :query-params (when to-send { :data (print-str to-send) }) :timeout 400 }
 59 |        (fn [{:keys [status headers body error]}]
 60 |          (if error
 61 |            (>!! request-chan [:http-error error [status headers]])
 62 |            (>!! request-chan (read-string body)))))
 63 |       (recur (alts!! [response-chan (timeout 500)])))))
 64 | 
 65 | (defn call-http-test
 66 |   "Wrap call-http with a test frame.
 67 | 
 68 | Stops http calls actually happening but replaces them with similar
 69 | async behaviour."  [monitor-url request-chan response-chan]
 70 |   (let [command-chan (chan)]
 71 |     (go
 72 |      (>! command-chan [:start :doit2])
 73 |      (>! command-chan [:noop])
 74 |      (>! command-chan [:start :doit])
 75 |      (>! command-chan [:start :nothere])
 76 |      (>! command-chan [:status])
 77 |      (>! command-chan [:exit]))
 78 |     (with-redefs
 79 |       [http-kit/post
 80 |        (fn [url options callback]
 81 |          (let [[command & args] (<!! command-chan)]
 82 |            (when args (println "command " command " the args were: " args))
 83 |            (println ">> the url is " url " options " options " and the command " command)
 84 |            (Thread/sleep (options :timeout))
 85 |            (>!! request-chan (if args
 86 |                                (apply conj [command] args)
 87 |                                [command]))))]
 88 |       (call-http monitor-url request-chan response-chan))))
 89 | 
 90 | (defn -main
 91 |   "Main for the spawner." [& args] ; we could take a monitor url
 92 |   (let [input (chan)
 93 |         output (chan)
 94 |         started (ref {})]
 95 | 
 96 |     ;; read messages from the command input
 97 |     (go-loop 
 98 |      [[message & args] (<! input)]
 99 |      (let [response ; capture the response from processing the message
100 |            (case message
101 |              :start (let [[id & rest] args]
102 |                       ;; Could add a test for id == :all here
103 |                       (if (scripts id)
104 |                         (dosync
105 |                          (alter started assoc id (start-process id (scripts id))))
106 |                         ;; Else there's an error
107 |                         [:error :notfound]))
108 |              :deploy (let [[id & rest] args] (println "redeploy " id " " args))
109 |              :kill (let [[id & rest] args]
110 |                      (when (@started args)
111 |                        (>! ((@started args) :from) :kill)))
112 |              :noop [:noop-received]
113 |              :status [:status (map #(% " started " (scripts %)) (keys @started))]
114 |              :http-error [:http-error "whoops! http error!"]
115 |              :exit (do (println "dieing!") [:quit])
116 |              true [:http-error "whoops! that's not a signal we understand"])]
117 |        (>! output (if response response []))) ; and send response so we recur http
118 |      (recur (<! input)))
119 |      
120 |     ;; read the signals from the started processes
121 |     (go-loop
122 |      [channels (keep #(% :from) (vals @started))]
123 |      (let [[[message id args] ch] (alts! (conj channels (timeout 100)))]
124 |        (case message
125 |          :line (println "process " id " read " message " with args: " args)
126 |          :exit (dosync (alter started dissoc id) (println id " exited"))
127 |          nil)
128 |        (recur (keep #(% :from) (vals @started)))))
129 | 
130 |     ;; Setup the http loop - this is the test mode.
131 |     (call-http-test "http://localhost:6001" input output)))
132 | 
133 | ;; spawner ends here
134 | 


--------------------------------------------------------------------------------
/LICENSE:
--------------------------------------------------------------------------------
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--------------------------------------------------------------------------------