Write a Plugin

Nomenclature

Use the haraka-plugin-[UNIQUE] naming style. We're moving towards npm packaging most plugins and the haraka-plugin prefix is the nomenclature we're using.

package plugin for release on npm.

mkdir haraka-plugin-example && cd haraka-plugin-example
touch index.js       // plugin code goes here
mkdir config test
echo '[main]' > config/example.ini
echo "var fixtures = require('haraka-test-fixtures');" > test/main.js
npm init
npm install --save <npm modules your plugin requires>
npm install --save-dev haraka-test-fixtures eslint eslint-plugin-haraka

config loading

Use this standard method for config loading:

exports.register = function () {
    var plugin = this;
    plugin.load_example_ini();
}
exports.load_example_ini = function () {
    var plugin = this;
    plugin.cfg = plugin.config.get('example.ini', function () {
        plugin.load_example_ini();
    }
}

• the callback added to config.get() lets your plugins config get updated immediately when the config changes. No Haraka restart required.
• storing the config contents at plugin.cfg lets the active configuration be accessed and manipulated by external processes. This is used heavily when adding test coverage.

booleans

If you have true/false booleans in your config, declare them and optionally, their defaults as well:

exports.load_example_ini = function () {
    var plugin = this;
    plugin.cfg = plugin.config.get('example.ini', {
        booleans: [
            '+enabled',               // plugins.cfg.main.enabled=true
            '-disabled',              // plugins.cfg.main.disabled=false
            '+feature_section.yes'    // plugins.cfg.feature_section.yes=true
        ]
    },
    function () {
        plugin.load_example_ini();
    }
}

enable Travis-CI testing

Add a .travis.yml config file to your repo:

language: node_js
node_js:
  - "4"
  - "6"

services:
# https://docs.travis-ci.com/user/database-setup/
#  - mongodb
#  - elasticsearch
#  - redis-server

before_script:

script:
    - npm run lint
    - npm test

after_success:

sudo: false

The services section can start up DB instances to test against. Use your favorite testing framework to write some basic tests, like config loading, connecting to DBs and then validating that your functions do what you expect.

Lint testing with eslint

We ask that you [at least mostly] use the coding style in haraka/recommended. We've made it easy by publishing an eslint plugin that imports them automatically. Add an .eslintrc.json file to your project dir:

{
  "plugins": [
    "haraka"
  ],
  "extends": ["plugin:haraka/recommended"],
  "rules": {
    "no-console": 0
  }
}

and add these two lines in the scripts section of package.json:

    "lint": "./node_modules/.bin/eslint *.js test/**/*.js",
    "lintfix": "./node_modules/.bin/eslint --fix *.js test/**/*.js",

Now you can lint test with npm run lint and correct any lint issues automatically with npm run lintfix. With Travis-CI enabled lint testing happens automatically (see the .travis.yml above) on every PR. This means that anyone submitting PRs against your plugin will have their changes linted automatically. It reduces errors and bugs and saves everyone time.

I also add "eslint:recommended" to the extends section and find it helpful. You may consider it too.