├── .gitignore ├── LICENSE ├── README.md ├── printenv.js └── sample_printenv_output.txt /.gitignore: -------------------------------------------------------------------------------- 1 | .env 2 | -------------------------------------------------------------------------------- /LICENSE: -------------------------------------------------------------------------------- 1 | GNU GENERAL PUBLIC LICENSE 2 | Version 2, June 1991 3 | 4 | Copyright (C) 1989, 1991 Free Software Foundation, Inc., 5 | 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA 6 | Everyone is permitted to copy and distribute verbatim copies 7 | of this license document, but changing it is not allowed. 8 | 9 | Preamble 10 | 11 | The licenses for most software are designed to take away your 12 | freedom to share and change it. By contrast, the GNU General Public 13 | License is intended to guarantee your freedom to share and change free 14 | software--to make sure the software is free for all its users. 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If this is what you want to do, use the GNU Lesser General 339 | Public License instead of this License. 340 | 341 | -------------------------------------------------------------------------------- /README.md: -------------------------------------------------------------------------------- 1 | 2 |
3 | 4 | # Learn Environment Variables [![HitCount](http://hits.dwyl.com/dwyl/learn-environment-variables.svg)](http://hits.dwyl.com/dwyl/learn-environment-variables) 5 | 6 | Learn how to use Environment Variables keep your secret keys safe & secure! 7 | 8 |
9 | 10 | ## *Why*? 🤷 11 | 12 | Avoid (*accidentally*) committing (*exposing*) your ***private keys***, ***passwords*** or other ***sensitive details*** 13 | (*by hard-coding in them in your script*) to GitHub by storing them 14 | as environment variables. 15 | 16 | > *Accidentally* pushing API keys to GitHub can be an *Expensive/Stressful Lesson*: 17 | https://www.quora.com/My-AWS-account-was-hacked-and-I-have-a-50-000-bill-how-can-I-reduce-the-amount-I-need-to-pay 18 | 19 | ## *What*? 💭 20 | 21 | An environment variable is a `KEY=value` pair that is stored on the 22 | local system where your code/app is being run and is accessible from within your code. 23 | 24 | If you are new to "***back end***" development, you may not have encountered 25 | environment variables 26 | before, this quick guide will tell you *all* you need to know! 27 | 28 | [The Twelve-Factor App](http://12factor.net/config) ***best practice*** 29 | recommends storing your app's configuration 30 | in the "*environment*", but what does that mean? 31 | 32 | > This *simply* means that you save any configuration both the values that are the 33 | same everywhere you run your app and the keys that change depending on where 34 | you are running the app, in the environment where you are running your app. 35 | 36 | ## *How*? 💻 37 | 38 | ### List all the *Default* Environment Variables 39 | 40 | In your terminal type: `printenv` and then the `enter` key. 41 | 42 | You should see something like this: 43 | ```js 44 | { 45 | TERM_PROGRAM: 'Apple_Terminal', 46 | SHELL: '/bin/bash', 47 | TERM: 'xterm-256color', 48 | TERM_PROGRAM_VERSION: '343.7', 49 | USER: 'n', 50 | PWD: '/Users/n/code/learn-environment-variables', 51 | LANG: 'en_GB.UTF-8', 52 | _system_arch: 'x86_64', 53 | _system_name: 'OSX', 54 | _: '/usr/local/bin/node' 55 | } 56 | ``` 57 | This is a list of all the variables defined in your environment, 58 | in this case we are running `printenv` on a Mac using the "Terminal" app, 59 | if you are on Linux/Unix using Bash/etc. 60 | you will see something slightly different. 61 | 62 | #### Log the list of environment variables available to node.js in `process.env` 63 | 64 | Node.js gives you access to the variables defined in your environment 65 | in the `process.env` ***global object***. 66 | 67 | Create a file called `printenv.js` and type/paste the following line in it: 68 | ```js 69 | console.log(process.env); 70 | ``` 71 | Run this script in your terminal: 72 | ```sh 73 | node printenv.js 74 | ``` 75 | 76 | ### Adding Variables to your Environment 77 | 78 | There are 3 ways to add variables to the environment where your app is running. 79 | 80 | #### 1. Command-Line Arguments 81 | 82 | When you run your node program/app you can include settings as environment variables 83 | for example, try running the following: 84 | 85 | ```sh 86 | PORT=1337 node printenv.js 87 | ``` 88 | Notice how the PORT variable is the *first element* displayed in the console? 89 | You are now able to access the `PORT` value in your node.js script 90 | by reference: `process.env.PORT` 91 | 92 | including your config in the command you use to run your script/app gets 93 | cumursome when you have lots of API Keys or Databases ... 94 | 95 | #### 2. Export the Variable to your Environment 96 | 97 | An improvement on this command-line arguments is to export the variable 98 | in your terminal: 99 | 100 | Type/paste this in your terminal window and tap enter: 101 | ```sh 102 | export HELLO=WORLD 103 | ``` 104 | Now `printenv` or `node printenv.js` to see it printed! 105 | the `HELLO` key is now available in the `process.env` object 106 | try adding the following line to your `printenv.js` file: 107 | 108 | ```js 109 | console.log(">> Hello", process.env.HELLO); 110 | ``` 111 | Now run it in your terminal: 112 | ```sh 113 | node printenv.js 114 | ``` 115 | What do you see? 116 | 117 | ```sh 118 | >> Hello WORLD 119 | ``` 120 | 121 | Exporting your keys to your environment using `export MY_VAR=HAI` works 122 | but if you use a terminal that does not *save* your variables across sessions, 123 | (e.g. if you close your terminal window!) you will have to keep exporting them! 124 | 125 | Thankfully there's a ***3rd*** (*easier*) ***way***: https://github.com/dwyl/env2 126 | 127 | #### 3. Use a `.env` file *locally* which you can `.gitignore` 128 | 129 | The way we prefer to manage our Environment Variables on our development machines 130 | is using a `.env` file which gets loaded into our app *once* and 131 | adds any entries in the `.env` file to the `process.env` (*global object*). 132 | 133 | We wrote the [**env2**](https://github.com/dwyl/env2) 134 | ***node.js module*** to load configuration from a `.env` or 135 | `.json` file. 136 | 137 | Loading your environment variables from a `.env` file is as easy as "ABC"! 138 | 139 | ##### A. Create your `.env` file 140 | 141 | Create a `.env` file in the root of your project and insert 142 | your key/value pairs in the following format of `KEY=VALUE`: 143 | 144 | ```sh 145 | DB_HOST=127.0.0.1 146 | DB_PORT=9200 147 | DB_USER=TheSpecial 148 | DB_PASS=EverythingIsAwesome 149 | ``` 150 | 151 | ##### B. Install `env2` and save it to your `package.json` 152 | 153 | Install the [**env2**](https://github.com/dwyl/env2) 154 | module from NPM and save it as a Dependency in your 155 | `package.json` file: 156 | 157 | ```sh 158 | npm install env2 --save 159 | ``` 160 | 161 | ##### C. Invoke `env2` and use the variable in your script 162 | 163 | Loading your configuration is a 1-line call to node.js's `require` method 164 | which loads [**env2**](https://github.com/dwyl/env2) and invokes it with 165 | your `.env` file as the argument: 166 | 167 | ```js 168 | require('env2')('.env'); // loads all entries into process.env 169 | 170 | console.log(process.env.DB_HOST); // "127.0.0.1" 171 | ``` 172 | 173 | Now you can access any of the entries in your `.env` file as a key 174 | in the `process.env` Object e.g: `process.env.PORT` is `9200` (in our example above). 175 | 176 | 177 | ##### D. Add `.env` to your `.gitignore` file! 178 | 179 | ```sh 180 | echo .env >> .gitignore 181 | ``` 182 | 183 | This ensures that the `.env` is not "tracked" in .git and thus 184 | will not be public on GitHub. i.e only visible on your local machine. 185 | If you are new/rusty on using `.gitignore` file to omit files/folders 186 | from your Git/GitHub repo read: http://git-scm.com/docs/gitignore 187 | 188 | 1[**env2**](https://github.com/dwyl/env2) solves the problem 189 | of loading config files, we *recommend* using [**env2**](https://github.com/dwyl/env2) because 190 | the ***code is clean, tested & documented***, 191 | but there are *other* solutions to this problem on NPM you can chose from 192 | depending on your needs. But if [**env2**](https://github.com/dwyl/env2) 193 | does cover your *specific* use-case, 194 | please tell us about it, we *always* love helping to solve problems and 195 | enhance our modules to be more useful to people! 196 | 197 | ## Environment Variable *Naming Convention* 198 | 199 | The Google Shell Style Guide (*naming convention*) states: 200 | **All caps, separated with underscores** 201 | so this is *Good*: 202 | ```sh 203 | export DATABASE_HOST=localhost 204 | ``` 205 | Whereas this is *Bad*: 206 | ```sh 207 | export databaseHost=localhost 208 | ``` 209 | 210 | see: https://google.github.io/styleguide/shell.xml#Constants_and_Environment_Variable_Names 211 | 212 | ## Removing an Environment Variable 213 | 214 | If you have exported an environment variable in your terminal, e.g: 215 | ```sh 216 | export PORT=8000 217 | ``` 218 | You can `unset` (*delete*) it by running: 219 | ```sh 220 | unset PORT 221 | ``` 222 | Now the `PORT` environment variable will no longer be set. 223 | 224 |
225 | 226 | ## Using *Environment Variables* with Travis-CI! [![Build Status](https://travis-ci.org/dwyl/learn-travis.svg?branch=master)](https://github.com/dwyl/repo-badges) 227 | 228 | > If you are ***new to Travis-CI*** 229 | check out our ***introductory tutorial*** (*for complete beginners*): 230 | https://github.com/dwyl/learn-travis 231 | 232 | There are **two ways** of telling Travis-CI about your environment variables: 233 | 234 | ### 1. Include Environment Variables in your `.travis.yml` file 235 | 236 | The easiest and most *explicit* way of listing your environment variables 237 | is to add them to your `.travis.yml` file: 238 | 239 | ```yml 240 | language: node_js 241 | node_js: 242 | - 6 243 | env: 244 | - MY_VAR=EverythignIsAwesome 245 | - NODE_ENV=TEST 246 | ``` 247 | The interesting part is the `env:` key where you can then list 248 | your environment variables and their corresponding values. 249 | 250 | ### 2. Add environment Variables in the Web Interface 251 | 252 | The *other* way of telling Travis-CI your environment variable(s) 253 | is to add them in the web-base user-interface (Web UI) in your project's settings page: 254 | 255 | ![add travis-ci environment variables Web UI](http://i.imgur.com/5ubG0fM.png) 256 | 257 | *Notice* how in if you add your environment variables in the the Travis Web UI 258 | they are hidden (*from the build log*) by default. 259 | This does *not* prevent you from accidentally `console.log` them and exposing a key/passord. 260 | So take care when console.logging ...! 261 | 262 | ### *Secure* (*Encrypted*) Environment Variables 263 | 264 | If you are storing sensitive information (*like API Keys or Database Passwords*) 265 | for use in your node app, the ***best way*** is to use the 266 | [***travis ruby gem***](http://docs.travis-ci.com/user/encryption-keys/) 267 | to ***encrypt*** your keys: 268 | 269 | You will need to have ruby installed on your computer, 270 | if you don't already have this, we recommend installing it with 271 | [**RVM**](http://stackoverflow.com/a/14182172/1148249): 272 | 273 | ```sh 274 | \curl -L https://get.rvm.io | bash -s stable --ruby 275 | rvm install current && rvm use current 276 | ``` 277 | Once you have installed ruby you can **install** the **travis ruby gem**: 278 | 279 | ```sh 280 | gem install travis 281 | ``` 282 | 283 | With the gem installed, you encrypt your variable by running the command 284 | in your terminal (*ensure you are in the working directory of your project*) 285 | 286 | ```sh 287 | travis encrypt MY_SECRET=super_secret 288 | ``` 289 | Type `yes` to confirm you are your project, you should now see your encrypted variable: 290 | 291 | ![learn-travis-encrypted-variable](http://i.imgur.com/7WP1Xe0.png) 292 | 293 | Paste this in your `.travis.yml` file and commit it to GitHub! 294 | 295 |
296 | 297 | 298 | ## Environment Variables on Heroku 299 | 300 | Visit your apps dashboard on heroku and click on the app you want to add 301 | an environment variable to: 302 | 303 | Go to `Settings` and Click `Reveal Config Vars` to view the `Config Vars`: 304 | ![heroku reveal config vars](http://i.imgur.com/99M0kWK.png) 305 | 306 | Next, click on `edit` and and add your desired key/value pair: 307 | 308 | ![add your env vars](http://i.imgur.com/kLp4X9P.png) 309 | 310 | That's all there is to it! 311 | 312 | ## Research & Background Reading 313 | 314 | + Detailed article: https://en.wikipedia.org/wiki/Environment_variable 315 | + The Twelve-Factor App > Configuration: http://12factor.net/config 316 | + Env vars on Arch Linux: https://wiki.archlinux.org/index.php/Environment_variables 317 | 318 | # Thanks! 319 | 320 | Thanks for learning about Environment Variables with us! 321 | If you have any questions, please ***ask***!! 322 | Please ⭐ this repo to help spread the word! 323 | 324 | If you are using environment variables in a way not mentioned in this readme, 325 | or have a better way of managing them or ***any*** other ***ideas 326 | or suggestions*** for improvements ***please tell us***!! 327 | -------------------------------------------------------------------------------- /printenv.js: -------------------------------------------------------------------------------- 1 | console.log(process.env); 2 | console.log(">> Hello ", process.env.HELLO); 3 | -------------------------------------------------------------------------------- /sample_printenv_output.txt: -------------------------------------------------------------------------------- 1 | { 2 | TERM_PROGRAM: 'Apple_Terminal', 3 | SHELL: '/bin/bash', 4 | TERM: 'xterm-256color', 5 | TERM_PROGRAM_VERSION: '343.7', 6 | USER: 'n', 7 | PWD: '/Users/n/code/learn-environment-variables', 8 | LANG: 'en_GB.UTF-8', 9 | _system_arch: 'x86_64', 10 | _system_name: 'OSX', 11 | _: '/usr/local/bin/node' 12 | } 13 | --------------------------------------------------------------------------------