Merge pull request #7 from kabirbaidhya/config-separation

Separate connection configurations to separate config files

.babelrc

@@ -1,4 +1,13 @@
 {
-    "presets": ["es2015"],
-    "plugins": []
+    "presets": [
+        "es2015"
+    ],
+    "plugins": [
+        [
+            "transform-es2015-for-of",
+            {
+                "loose": true
+            }
+        ]
+    ]
 }

.gitignore

@@ -1,4 +1,4 @@
 dist/
 node_modules
-.pglistend.yml
+.pglistend*.yml
 *.log

.pglistend-connection.yml.dist

@@ -0,0 +1,15 @@
+# database connection
+connection:
+    database: DATABASE_NAME
+    user: YOUR_USERNAME
+    password: PASSWORD
+    port: 5432
+    max: 2
+
+# channels to LISTEN to
+channels: [CHANNEL_1, CHANNEL_2]
+
+# list of listener scripts to be included
+scripts:
+    - /path/to/listener/script.js
+#    - path/to/another/listener-script.js

.pglistend.yml.dist

@@ -0,0 +1,12 @@
+default:
+    connection:
+        host: localhost
+        port: 5432
+        max: 2
+        idleTimeoutMillis: 10000
+
+# Include configuration files database connections you want to use
+connections:
+    - /path/to/.pglistend-connection.yml
+    - /path/to/another/.pglistend-connection.yml
+

README.md

@@ -84,5 +84,4 @@ Check [this](https://www.digitalocean.com/community/tutorials/how-to-use-journal
 6. From terminal in root directory, run: `npm start`. You can see the logs in terminal as the channels hit the queries when the `notify` operation is called on.
 
 ## TODOs
-* Multiple database support as right now it supports single database only.
 * Delegate CPU-intensive tasks (mostly queries) to separate thread or message queue most likely. [Here's why](http://stackoverflow.com/questions/3491811/node-js-and-cpu-intensive-requests/3536183#answer-3491931)

listener.js.dist

@@ -0,0 +1,11 @@
+module.exports = function(h) {
+    return {
+        'channel_1': function(payload) {
+            // Do something
+        },
+
+        'channel_2': function(payload) {
+            // Do something
+        }
+    };
+};

package.json

@@ -28,6 +28,7 @@
   "dependencies": {
     "chalk": "^1.1.3",
     "commander": "^2.9.0",
+    "deep-assign": "^2.0.0",
     "es6-shim": "^0.35.1",
     "lodash.debounce": "^4.0.6",
     "lodash.throttle": "^4.0.1",
@@ -38,6 +39,7 @@
     "babel-cli": "^6.10.1",
     "babel-eslint": "^5.0.0",
     "babel-preset-es2015": "^6.9.0",
+    "babel-plugin-transform-es2015-for-of": "^6.8.0",
     "eslint": "2.2.0",
     "nodemon": "^1.9.2"
   },
@@ -48,6 +50,9 @@
   "files": [
     "bin/",
     "dist/",
-    "setup"
+    "setup",
+    ".pglistend.yml.dist",
+    ".pglistend-connection.yml.dist",
+    "listener.js.dist"
   ]
 }

setup/setup.py

@@ -33,6 +33,20 @@
 
 # Configuration file template
 CONFIG_TEMPLATE = '''
+default:
+    connection:
+        host: localhost
+        port: 5432
+        max: 2
+        idleTimeoutMillis: 10000
+
+# Include configuration files database connections you want to use
+connections:
+#   - path/to/connection-config.yml
+'''
+
+# Connection config file template
+CONNECTION_CONFIG_TEMPLATE = '''
 # Change the following configuration parameters according to your need.
 
 # postgresql connection
@@ -57,11 +71,18 @@
 DEFAULT_LISTENER_TEMPLATE = '''
 // Here you can define handlers for each of the channels
 // that are being LISTENed.
-module.exports = {
-    // 'boom': function(payload) {
-    //     console.log('Received notification on channel "boom"', payload);
-    // }
+module.exports = function(h) {
+    return {
+        'channel_1': function(payload) {
+            // Do something
+        },
+
+        'channel_2': function(payload) {
+            // Do something
+        }
+    };
 };
+
 '''
 
 # Constants

src/Listener.js

@@ -1,9 +1,9 @@
 import {Client, Pool} from 'pg';
 import {format} from 'util';
 import {yellow, green, red, dim} from 'chalk';
+
 import {halt} from './program';
 import {log, error} from './util';
-
 import * as msg from './messages/common';
 
 class Listener {
@@ -58,14 +58,15 @@ class Listener {
         }
 
         // TODO: Delegate CPU-intensive jobs to a task queue or a separate process.
-        
+
         handlers.forEach(callback => callback(payload));
     }
 
     handle(notification) {
+        const database = this.client.database;
         const {channel, payload: str} = notification;
 
-        log(msg.RECEIVED_NOTIFICATION, green(channel), dim(str || '(empty)'));
+        log(msg.RECEIVED_NOTIFICATION, green(database + ':' + channel), dim(str || '(empty)'));
 
         try {
             const payload = this.parsePayload(str);
@@ -78,8 +79,10 @@ class Listener {
     }
 
     listenTo(channel) {
+        const database = this.client.database;
+
         this.client.query(`LISTEN ${channel}`).then(() => {
-            log(msg.STARTED_LISTENING, green(channel));
+            log(msg.STARTED_LISTENING, green(database + ':' + channel));
 
             // Warn if handlers are not registered for the channels being listened to
             if (!Array.isArray(this.handlers[channel])) {

src/messages/common.js

@@ -4,4 +4,7 @@ export const RECEIVED_NOTIFICATION = 'Received notification on channel %s: %s';
 export const DATABASE_CONNECTED = 'Connected to database %s';
 export const STARTED_LISTENING = 'Started listening to channel %s';
 export const SETUP_ERROR = 'Setup could not be completed.';
-export const GENERIC_ERROR_MESSAGE = 'An error occurred.';
+export const GENERIC_ERROR_MESSAGE = 'An error occurred.';
+export const LOADED_CONFIG_FILE = 'Loaded configuration file: %s';
+export const ERROR_LOADING_CONFIG_FILE = 'Error loading configuration file: %s';
+export const NO_CONNECTIONS_CONFIGURED = 'No database connections are configured. Please do configure properly and start pglistend again.';

src/program.js

@@ -16,7 +16,7 @@ export function run() {
         .description('pglisten - Postgres LISTEN CLI tool')
         .usage('--config=<path>')
         .option('-c, --config <path>', 'Configuration file to use');
-    
+
     prog.command('setup-daemon')
         .description('Setup pglistend service on this system')
         .option('-C, --configure', 'Configure the daemon during setup')
@@ -43,9 +43,12 @@ export function halt(err) {
 function listen(args) {
     let config = resolveConfig(args.config);
 
-    for (let i = 0; i < config.connections.length; i++) {
-        let configuration = config.connections[i];
-        let listener = new Listener(configuration, resolveHandlers(configuration));
+    if (config.connections.length === 0) {
+        throw new Error(msg.NO_CONNECTIONS_CONFIGURED);
+    }
+
+    for (let connection of config.connections) {
+        let listener = new Listener(connection, resolveHandlers(connection));
 
         listener.listen();
     }

src/resolver.js

@@ -1,12 +1,38 @@
+import {Pool} from 'pg';
 import Yaml from 'yamljs';
+import {yellow} from 'chalk';
+import deepAssign from 'deep-assign';
+
 import query from './query';
-import {Pool} from 'pg';
 import {log, error} from './util';
 import {throttle, debounce} from './util';
 import {isObject, isFunction} from './util';
+import * as msg from './messages/common';
 
 export function resolveConfig(file) {
-    return Yaml.load(file);
+    let config = loadConfig(file);
+
+    config.connections = resolveConnections(config.connections, config.default);
+
+    return config;
+}
+
+function resolveConnections(files, defaults = {}) {
+    if (!Array.isArray(files)) return [];
+
+    return files.map(path => deepAssign({}, loadConfig(path), defaults));
+}
+
+function loadConfig(file) {
+    try {
+        let config = Yaml.load(file);
+
+        log(msg.LOADED_CONFIG_FILE, yellow(file));
+        return config;
+    } catch (e) {
+        error(msg.ERROR_LOADING_CONFIG_FILE, file);
+        throw e;
+    }
 }
 
 export function resolveHandlers(config) {