safelink
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SafeLink is an open-source NodeJS library created to maintain long-term communication between distant remote sites with varying network quality
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JavaScript
/**
*
* Copyright 2013 Joel Grenon
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
var util = require('util'),
http = require('http'),
Q = require('q'),
/* jshint ignore:start */
JSON = require('json3'),
/* jshint ignore:end */
shortId = require('shortid'),
_ = require('lodash'),
moment = require('moment'),
redis = require('redis'),
async = require('async'),
bunyan = require('bunyan'),
WebSocketServer = require('ws').Server,
WatchDog = require('./watchdog'),
Handlebars = require('handlebars'),
fs = require('fs'),
EventEmitter = require('eventemitter3');
require("underscore-query");
var Dispatcher = (function() {
var server;
const protocolMap = require('./protocol');
const VERSION = 100;
const pendingCommands = [];
const watchDogs = {};
const monitors = {};
/**
* @class Dispatcher
* @extend EventEmitter
* @description The dispatcher is responsible for central coordination of all agents. It monitors their liveness and make sure they can communication between one and other.
* The Dispatcher is an {EventEmitter} and will make sure events are remotely replicated between agents.
* @param cfg
* @constructor
*/
function Dispatcher(cfg) {
var _this = this;
this.port = cfg.port || 8080;
this.log = cfg.log || bunyan.createLogger({name:'dispatcher', level: cfg.logLevel || 'info'});
this.pendingCleanupThreshold = cfg.command_cleanup_threshold || 600;
this.commandHandlers = {};
this.agentSockets = {};
this.statusReportTmpl = Handlebars.compile(fs.readFileSync(__dirname + '/status_report.hbs') + "");
this.statusReportData = {agents:{}};
EventEmitter.call(this);
if(!cfg.redis) {
cfg.redis = {
port: 6379,
host: 'localhost'
}
}
this.db = redis.createClient(cfg.redis.port, cfg.redis.host);
this.db.on('error', _.bind(function(e) {
/**
* @event internal.db.error
* @description Triggered if the internal Redis database cannot be accessed.
* @param e {Error} The error that has been sent.
*/
this.emit('internal.db.error', e);
}, this));
this.eventSubscriptions = [];
server = http.createServer(function(req, res) {
if(_this.suspended) {
res.statusCode = 503;
res.end("SUSPENDED");
}
else {
if (req.method === 'POST') {
var body = '';
req.on('data', function (data) {
body += data;
});
req.on('error', function(err) {
_this.log.error(err);
res.send("error");
});
req.on('end', function () {
var content = {};
if(body.length > 0) {
try {
content = JSON.parse(body);
// Do something...
var handler = protocolMap[content.key];
if(handler) {
Q.fcall(_.bind(handler, _this), content).then(function(result) {
res.end(JSON.stringify({success:true, v:VERSION, data: result}));
}, function(err) {
res.end(JSON.stringify({success:false, v:VERSION, error:err}));
}).catch(function(err) {
res.end(JSON.stringify({success:false, v:VERSION, error:err}));
});
}
else {
res.end(JSON.stringify({success:false, error:'unknown-key:'+content.key, v:VERSION}));
}
}
catch(err) {
_this.log.error(err);
}
}
});
}
else if(req.method === 'GET') {
// Produce the safelink status report
_this.statusReportData.PENDING = _.filter(pendingCommands, function(c) { return c.status === 'PENDING'}).length;
_this.statusReportData.COMPLETE = _.filter(pendingCommands, function(c) { return c.status === 'COMPLETE'}).length;
_this.statusReportData.ACTIVE = _.filter(pendingCommands, function(c) { return c.status === 'ACTIVE'}).length;
res.end(_this.statusReportTmpl(_this.statusReportData));
}
else
res.end(JSON.stringify({success:false, v:VERSION, error:"Unsupported method"}));
}
});
server.on('connection', function(socket) {
socket.setTimeout(300 * 1000);
});
// Initialize the WebSocket server
if(cfg.wss) {
var wss = new WebSocketServer({port: cfg.wss.port});
// Handle agent connections. Register all message handlers
wss.on('connection', function(ws) {
ws.on('message', function(msg) {
try {
var content = JSON.parse(msg);
// Bind this socket to an agent id
_this.agentSockets[content.id] = ws;
_this.log.trace("Received message through websocket", content);
// Do something...
var handler = protocolMap[content.key];
if(handler) {
Q.fcall(_.bind(handler, _this), content).then(function(result) {
// Write response through the ws
ws.send(JSON.stringify({
key: 'message-response',
uuid: content.uuid,
data: result
}));
}, function(err) {
// Write error through the ws
ws.send(JSON.stringify({
key:'message-error',
uuid: content.uuid,
error: err
}));
}).catch(function(err) {
// Write error through the ws
ws.send(JSON.stringify({
key:'message-error',
uuid: content.uuid,
error: err
}));
});
}
else
_this.log.warn("No handler was configured for command", content.key);
}
catch(err) {
_this.log.error(err);
}
});
ws.on('close', function(ws) {
_this.log.warn("TODO: Closing socket:",ws);
});
});
}
// Launch a command cleanup job to clear completed and lost commands
this.commandMonitorInterval = setInterval(function() {
_this.log.debug("Analyzing %d pending commands for cleanup", pendingCommands.length);
_this.statusReportData.GARBAGE_COLLECTED = 0;
async.forEach(pendingCommands, function(cmd, callback) {
var delta = moment().utc().unix() - cmd.ts;
_this.log.trace(cmd, "Checking command for cleanup");
// First process active commands with no results
if(cmd.status !== 'COMPLETE' && delta > _this.pendingCleanupThreshold) {
cmd.defer.reject(new Error("no-response"));
cmd.status = 'COMPLETE';
_this.statusReportData.GARBAGE_COLLECTED++;
_this.log.warn("Command %s(%s) for agent %s is now dead and will be cleaned-up", cmd.id, cmd.key, cmd.agentId);
}
if(cmd.status === 'COMPLETE') {
_this.log.trace("Cleaning completed command %s", cmd.id);
// Remove from pendingCommands
_.remove(pendingCommands, function(c){ return c.id === cmd.id });
// Remove from Redis
_this.db.del(cmd.id);
_this.statusReportData.GARBAGE_COLLECTED++;
_this.log.trace("Command %s:%s(%s) has been removed from system", cmd.agentId, cmd.id, cmd.key);
}
callback();
}, function(err) {
if(err)
_this.log.error(err, "There was a problem while we were cleaning up commands... error is", err);
else
_this.log.debug("Cleanup report: %d remaining pending commands after cleanup", pendingCommands.length);
});
}, 30000);
this.on('agent-connected', function(e) {
e.meta = e.meta || {};
e.agent = e.agent || {};
// Create a new structure for this agent
this.db.multi()
.hset(e.id, "connectedTs", e.ts)
.hset(e.id, "lastHeartbeatTs", e.ts)
.hset(e.id, "version", e.agent.version || "1")
.hset(e.id, "heartbeat-interval", e.meta.interval || 30)
.exec(function(err) {
if(err)
_this.log.error(err);
else {
_this.ensureWatchDog({id: e.id, interval: e.meta.interval || 30}).then(function(watchdog) {
// Force the execution of a configure command on the agent
_this.executeOnAgent(e.id, 'configure', {restart: false});
}, function(err) {
_this.log.warn("Unable to install watchdog for agent %s. Error = ", e.id, err);
});
}
});
});
this.on('agent-disconnected', function(e) {
_this.log.warn("Agent %s was detected as disconnected", e.id);
// Clear all pending commands and mark them as canceled
// Close any open web socket connection
if(_this.agentSockets[e.id]) {
_this.agentSockets[e.id].close();
delete _this.agentSockets[e.id];
}
});
}
util.inherits(Dispatcher, EventEmitter);
/**
* @method listen
* @description Connect the HTTP server to the configured port.
* @returns {Promise} Resolved when the dispatcher is ready to receive commands.
*/
Dispatcher.prototype.listen = function() {
var defer = Q.defer();
server.listen(this.port, defer.makeNodeResolver());
return defer.promise;
};
Dispatcher.prototype.suspend = function(duration) {
var _this = this;
if(!this.suspended) {
this.suspended = true;
this.log.warn("Dispatcher is now suspended");
if(duration) {
setTimeout(function() {
_this.resume();
}, duration * 1000);
}
}
else
this.log.debug("Already suspended, new suspend request will be ignored");
};
Dispatcher.prototype.resume = function() {
if(this.suspended) {
this.suspended = false;
this.log.warn("Dispatcher is now resuming normal operation");
}
else
this.log.info("Dispatcher was already executing normally. Resume request will be ignored");
};
/**
* {
agent:request.id,
key:request.payload.key,
interval: request.payload.interval || 5,
snapshots: request.payload.snapshots || "ALL"
}
*
* @param cfg
*/
Dispatcher.prototype.installMonitor = function(cfg) {
if(!monitors[cfg.agent]) {
monitors[cfg.agent] = setInterval(_.bind(function() {
var snapshot = {
agents:this.listConnectedAgents(),
pendingCommands:this.listPendingCommands(cfg.agent).length
};
// Send a system-status event to the agent
this.emitTo(cfg.agent, snapshot);
}, this), cfg.interval);
}
else
return Q(monitors[cfg.agent]);
};
Dispatcher.prototype.uninstallMonitor = function(agent, key) {
if(monitors[agent]) {
clearInterval(monitors[agent]);
delete monitors[agent];
}
};
Dispatcher.prototype.listConnectedAgents = function() {
return _.map(_.values(watchDogs), function(w) {
return w.agent;
});
};
/**
* @method listPendingCommands
* @description List all pending commands for a specific agent
* @param agentId {String} An agentId
* @returns {Array} A list of pending commands. Each command has the following fields:
*
* - id
* - agentId
* - defer: The deferred result
* - status: the status of the command : PENDING | ACTIVE | COMPLETE
* - ts : The unix timestamp when this command was created
*/
Dispatcher.prototype.listPendingCommands = function(agentId) {
return _.q(pendingCommands, {agentId:agentId, status: 'PENDING'});
};
/**
* Execute a command on a specific agent
*
* @method executeOnAgent
* @param agentId {String} The agentId where the command will be executed
* @param commandKey {String} The command key that identified this command
* @param payload {Object} The data that will be passed with the command
* @param options {Object} Contains options that affects the way the command is executed
* @returns {Promise} A promise providing access to the command result when available.
*/
Dispatcher.prototype.executeOnAgent = function(agentId, commandKey, payload, options) {
var _this = this;
var defer = Q.defer();
options = options || {};
payload = payload || {};
Q.nextTick(_.bind(function() {
var cmdId = options.uuid || shortId.generate();
var ts = moment().utc().unix();
this.log.debug("Executing command %s(%s) on agent %s", commandKey, cmdId, agentId);
this.log.trace("Executing command %s(%s) with payload", commandKey, cmdId, payload);
// We default to single command group
var group = cmdId;
// If a group is specified, we group commands based on their key by default or using a custom key provided by the caller
if(options && options.group) {
group = options.group.key || agentId+commandKey;
}
// If we have a socket, just send a command message right now
if(this.agentSockets[agentId]) {
this.log.debug("Sending command %s(%s) directly using established web socket channel", commandKey, cmdId);
this.agentSockets[agentId].emit('command', {
id: cmdId,
key: commandKey,
agent: agentId,
ts: ts,
group: group,
payload: JSON.stringify(payload || {}),
options: JSON.stringify(options || {})
}, function(err) {
if(!err) {
this.db.multi()
.hset(cmdId, "id", cmdId)
.hset(cmdId, "key", commandKey)
.hset(cmdId, "agent", agentId)
.hset(cmdId, "ts", ts)
.hset(cmdId, "group", group)
.hset(cmdId, "payload", JSON.stringify(payload || {}))
.hset(cmdId, "options", JSON.stringify(options || {}))
.exec(function(err) {
if(err) {
_this.log.error("Unable to register command in Redis", err);
defer.reject(err);
}
else {
_this.log.debug("Adding command %s(%s) to pending command list for agent %s", commandKey, cmdId, agentId);
// Add this command to our pending list
var cmd = {
id:cmdId,
agentId: agentId,
key: commandKey,
defer:defer,
group: group,
status: 'ACTIVE',
timeout: options.timeout || _this.timeout,
ts: ts
};
pendingCommands.push(cmd);
}
});
}
else {
_this.log.error(err);
defer.reject(err);
}
}.bind(this));
}
else {
// Make sure we drop all pending requests (from other groups) if we're instructed to
if(options && options.dropAllPending) {
if(_.isString(options.dropAllPending)) {
_.each(_.query(pendingCommands, {agentId:agentId, key:options.dropAllPending, group: {$ne : group}, status:'PENDING'}), function(command) {
command.defer.resolve({success:true, dropped:true});
command.status = 'COMPLETE';
});
}
else {
_.each(_.query(pendingCommands, {agentId:agentId, group: {$ne : group}, status:'PENDING'}), function(command) {
command.defer.resolve({success:true, dropped:true});
command.status = 'COMPLETE';
});
}
}
this.db.multi()
.hset(cmdId, "id", cmdId)
.hset(cmdId, "key", commandKey)
.hset(cmdId, "agent", agentId)
.hset(cmdId, "ts", ts)
.hset(cmdId, "group", group)
.hset(cmdId, "payload", JSON.stringify(payload || {}))
.hset(cmdId, "options", JSON.stringify(options || {}))
.exec(function(err) {
if(err) {
_this.log.error("Unable to register command in Redis", err);
defer.reject(err);
}
else {
_this.log.debug("Adding command %s(%s) to pending command list for agent %s", commandKey, cmdId, agentId);
// Add this command to our pending list
var cmd = {
id:cmdId,
agentId: agentId,
key: commandKey,
defer:defer,
group: group,
status: 'PENDING',
timeout: options.timeout || _this.timeout,
ts: ts
};
pendingCommands.push(cmd);
}
});
}
}, this));
return defer.promise;
};
/**
* @method emitTo
* @description Emit an event to a specific agent only.
* @param agentId {String|Array} The agent where the event is to be sent. This may be an array of agentIds.
* @param key {String} The event key that is being sent
* @param data The event payload
* @param options
* @returns {Promise} A promise resolved when the event has been retrieved by the agent (or agents)
*/
Dispatcher.prototype.emitTo = function(agentId, key, data, options) {
var _this = this;
var defer = Q.defer();
options = options || {};
Q.nextTick(function() {
if(_.isString(agentId)) agentId = [agentId];
async.forEach(agentId, function(id, done) {
_this.db.rpush(id+"_events", JSON.stringify({key: key, data:data}));
done();
}, function(err) {
if(err) defer.reject(err);
else
defer.resolve();
});
});
return defer.promise;
};
/**
* @method applyCommandResponse
* @description Called when an agent has sent back the response to an active command. This will apply the response and resolve the
* associated promise.
* @param cmdId The id of the command associated with the response
* @param result The actual command response
* @returns {defer.promise|*} The promise associated with the applyCommand operation and not the promise associated with the command itself.
*/
Dispatcher.prototype.applyCommandResponse = function(cmdId, result) {
var _this = this;
var defer = Q.defer();
Q.nextTick(function() {
_this.log.debug("Applying command response for command %s", cmdId);
_this.log.trace("Command %s response", result);
var commands = _.query(pendingCommands, {id:cmdId});
if(commands.length === 1) {
_this.log.debug("Command %s was successfully found in our pending command list", cmdId);
_this.log.trace("Command found", commands[0]);
// We load all commands of the same group. They will all be resolved by the same result (including this one)
var groupCommands = _.query(pendingCommands, {group: commands[0].group, status: 'PENDING'});
groupCommands.push(commands[0]);
_this.log.debug("Found %d commands that will be fulfilled by this response", groupCommands.length);
async.forEach(groupCommands, function(command, done) {
_this.log.trace("Fulfilling command %s(%s)", command.key, command.id);
command.defer.resolve(result);
command.status = 'COMPLETE';
done();
}, function() {
_this.log.debug("Command response was successfully applied");
defer.resolve({success:true});
});
}
else {
_this.log.warn("Unable to find command %s in our pending command list. Most probably a timeout and command was already cleaned up", cmdId);
defer.reject({success:false, error:"Unknown command:"+cmdId});
}
});
return defer.promise;
};
Dispatcher.prototype.applyCommandError = function(cmdId, error) {
var defer = Q.defer();
Q.nextTick(function() {
var commands = _.query(pendingCommands, {id:cmdId});
if(commands.length === 1) {
var groupCommands = _.query(pendingCommands, {group: commands[0].group, status: 'PENDING'});
groupCommands.push(commands[0]);
async.forEach(groupCommands, function(command, done) {
command.defer.reject(error);
command.status = 'COMPLETE';
done()
}, function() {
defer.resolve({success:true});
});
}
else {
defer.reject({success:false, error: "Unknown command:"+cmdId});
}
});
return defer.promise;
};
Dispatcher.prototype.applyCommandProgress = function(cmdId, progress) {
var defer = Q.defer();
Q.nextTick(function() {
var commands = _.query(pendingCommands, {id:cmdId});
if(commands.length === 1) {
var groupCommands = _.query(pendingCommands, {group: commands[0].group, status: 'PENDING'});
groupCommands.push(commands[0]);
async.forEach(groupCommands, function(command, done) {
command.defer.notify({cmd: _.pick(command, "id", "key", "group"), data:progress});
done();
}, function() {
defer.resolve();
});
}
else {
defer.reject({success:false, error: "Unknown command:"+cmdId});
}
});
return defer.promise;
};
Dispatcher.prototype.startAgentWatchDog = function(agent) {
var _this = this;
var defer = Q.defer();
Q.nextTick(function() {
watchDogs[agent.id] = new WatchDog(agent, _this);
_this.log.info("Watchdog installed for agent %s", agent.id);
defer.resolve(watchDogs[agent.id]);
});
return defer.promise;
};
Dispatcher.prototype.stopAgentWatchDog = function(agentId) {
clearInterval(watchDogs[agentId]);
};
Dispatcher.prototype.ensureWatchDog = function(agent){
if(!watchDogs[agent.id]) {
return this.startAgentWatchDog(agent);
}
return Q(watchDogs[agent.id]);
};
Dispatcher.prototype.hasWatchDog = function(agentId) {
return !_.isUndefined(watchDogs[agentId]);
};
return Dispatcher;
})();
module.exports = Dispatcher;