node-haproxy

Set, modify and hot load haproxy configuration from node.

Functionality and code lifted and adapted from thalassa=aqueduct.

You can run this module standalone (npm install -g node-haproxy; node-haproxy --ipc) and communicate with it using ipc (var ipcClient = require ('node-haproxy/src/ipc-client') or use the api directly (var haproxy = require('node-haproxy').

In both cases it will fire up a haproxy instance which you can query and modify programmatically.

When modifying or adding/removing front and backends programmatically haproxy is reconfigured on the fly. Back and frontends are persisted between restarts of the node process.

Changes are saved to a leveldb.

When no options are passed in, the included haproxy executable (v1.5) is used. The leveldb and persisted data is stored by default in the module's folder. Which means that on updating or reinstalling the module the data is wiped.

Locations of the leveldb, template haproxy.cfg file and persisted info file can be set using options, amongst some more settings relating to haproxy.

Paraphrased from the original readme:

HAProxy Fundamentals

Node-haproxy does not try to obfuscate HAProxy, and it's important to know the fundamentals of how HAProxy works to understand node-haproxy. The API mirrors HAProxy's semantics. The HAProxy documentation contains a wealth of detailed information.

1. Frontends - A "frontend" section describes a set of listening sockets accepting client connections.

2. Backends - A "backend" section describes a set of servers to which the proxy will connect to forward incoming connections.

3. Members/Servers - node-haproxy calls the servers that backends route to "members". In other words, members of a backend pool of servers.

4. Config file - At startup, HAProxy loads a configuration file and never looks at that file again. node-haproxy manages this by re-templating a new config file and gracefully restarting the HAProxy process.

5. Stats Socket - a UNIX socket in stream mode that will return various statistics outputs and even allows some basic configuration tweaking like enabling and disabling existing backend members, setting weights, etc.

Options

 ./node_modules/.bin/node-haproxy --help
Options:
--haproxySocketPath  path to Haproxy socket file
--haproxyPidPath     path to  Haproxy pid file
--haproxyCfgPath     generated Haproxy config location
--templateFile       template used to generate Haproxy config
--persistence        directory to save configuration
--dbPath             filesystem path for leveldb
--sudo               use sudo when starting haproxy
--which              path for haproxy, set to 'system' to look for it, otherwise the included haproxy (v1.5) is used
  --ipc                start up ipc server

The following functions can be invoked on the required node-haproxy module or using the ipc-client (ipcClient(functionName, args), which uses promises: Don't forget to call ipcClient.close() if you want to stop the node process..

Example of using the ipc-client:

ipcClient('getFrontends', [])
  .when(
    function(result) {
      console.log("Frontends\n", result);
      return ipcClient('getBackends', []);
    })
  .when(
    function(result) {
      console.log("Backends\n", result);
      ipcClient.close();
    },
    function(error) {
      console.log("Error\n", error);
      ipcClient.close();
    }

  );

getFrontends()

Returns Array of frontend objects for all of the frontends configured

For example:

[{
    "id": "frontend/myapp",
    "_type": "frontend",
    "key": "myapp",
    "bind": "*:8080,*:80",
    "backend": "live",
    "mode": "http",
    "keepalive": "default",
    "rules": [{
        "type": "header",
        "header": "host",
        "operation": "hdr_dom",
        "value": "staged.myapp.com",
        "backend": "staged"
    }],
    "natives": []
}]

getFrontend(key)

Gets a specific frontend by key.

putFrontend(key, obj)

Create or update a frontend by key.

{
    "bind": "10.2.2.2:80,*:8080" // IP and ports to bind to, comma separated, host may be *
  , "backend": "foo"      // the default backend to route to, it must be defined already
  , "mode": "tcp"         // default: http, expects tcp|http
  , "keepalive": "close"  // default: "default", expects default|close|server-close
  , "rules": []           // array of rules, see below
  , "natives": []         // array of strings of raw config USE SPARINGLY!!
}

deleteFrontend(key)

Delete a specific frontend by key.

getBackends()

Returns Array of backend objects for all of the backends configured

For example:

[{
	"id": "backend/live",
	"_type": "backend",
	"key": "live",
	"type": "dynamic",
	"name": "classroom-ui",
	"version": "1.0.0",
	"balance": "roundrobin",
	"host": null,
	"mode": "http",
	"members": [{
		"name": "myapp",
		"version": "1.0.0",
		"host": "10.10.240.121",
		"port": 8080,
		"lastKnown": 1378762056885,
		"meta": {
			"hostname": "dev-use1b-pr-01-myapp-01x00x00-01",
			"pid": 17941,
			"registered": 1378740834616
		},
		"id": "/myapp/1.0.0/10.10.240.121/8080"
	},
	{
		"name": "myapp",
		"version": "1.0.0",
		"host": "10.10.240.80",
		"port": 8080,
		"lastKnown": 1378762060226,
		"meta": {
			"hostname": "dev-use1b-pr-01-myapp-01x00x00-02",
			"pid": 18020,
			"registered": 1378762079883
		},
		"id": "/myapp/1.0.0/10.10.240.80/8080"
	}],
	"natives": []
}]

getBackend(key)

Gets a specific backend by key.

putBackend(key, obj)

Create or update a backend by key.

{
    "type" : "dynamic|static" 
  , "name" : "foo" // only required if type = dynamic
  , "version" : "1.0.0" // only required if type = dynamic
  , "balance" : "roundrobin|source" // defaults to roundrobin
  , "host" : "myapp.com"  // default: undefined, if specified request to member will contain this host header
  , "health" : {                 // optional health check
  	  "method": "GET"            // HTTP method
  	, "uri": "/checkity-check"   // URI to call
  	, "httpVersion": "HTTP/1.1"  // HTTP/1.0 or HTTP/1.1 `host` required if HTTP/1.1
  	, "interval": 5000           // period to check, milliseconds
  }
  , "mode" : "http|tcp" // default: http
  , "natives": []  // array of strings of raw config USE SPARINGLY!!
  , "members" : [] // if type = dynamic this is dynamically populated based on role/version subscription
                   // otherwise expects { host: '10.10.10.10', port: 8080}
}

deleteBackend(key)

Delete a specific backend by key.

updateBackend(key)

Update a backends role and version

{
    "name": "myapp"		
  , "version": "1.1.0" // version to route to
}

name is actually optional. You may also just send the version:

{
    "version": "1.1.0"
}

getHaproxyConfig()

Return the last know generated HAProxy config file contents that were written to the location of opts.haproxyCfgPath.

global
  log 127.0.0.1 local0
  log 127.0.0.1 local1 notice
  daemon
  maxconn 4096
  user haproxy 
  group haproxy 
  stats socket /tmp/haproxy.status.sock user appuser level admin

  defaults
    log global
    option dontlognull
    option redispatch
    retries 3
    maxconn 2000
    timeout connect 5000ms
    timeout client 50000ms
    timeout server 50000ms

  listen stats :1988
    mode http
    stats enable
    stats uri /
    stats refresh 2s
    stats realm Haproxy\ Stats
    stats auth showme:showme


  frontend myapp
    bind *:8080,*:80
	mode http
	default_backend live
	option httplog
	option http-server-close
	option http-pretend-keepalive
	acl header_uv7vi hdr_dom(host) myapp-staged.com
	use_backend staged if header_uv7vi



  backend live
    mode http
	balance roundrobin
	server live_10.10.240.121:8080 10.10.240.121:8080 check inter 2000
	server live_10.10.240.80:8080 10.10.240.80:8080 check inter 2000

  backend staged
    mode http
	balance roundrobin
	server staged_10.10.240.174:8080 10.10.240.174:8080 check inter 2000
	server staged_10.10.240.206:8080 10.10.240.206:8080 check inter 2000

Routing Rules

There are currently 3 types of rules that can be applied to frontends: path, url, and header.

Path rules support path, path_beg, and path_reg HAProxy operations

{
    "type": "path"
  , "operation": "path|path_beg|path_reg"
  , "value": "favicon.ico|/ecxd/|^/article/[^/]*$"
  , "backend": "foo" // if rule is met, the backend to route the request to
}

Url rules support url, url_beg, and url_reg HAProxy operations

{
    "type": "url"
  , "operation": "url|url_beg|url_reg"
  , "value": "/bar" // value for the operation
  , "backend": "bar" // if rule is met, the backend to route the request to
}

Header rules support hdr_dom with a entire value at this point

{
    "type": "header"
  , "header": "host"			// the name of the HTTP header
  , "operation": "hdr_dom"
  , "value": "baz.com"
  , "backend": "baz" // if rule is met, the backend to route the request to
}

Natives

The natives property is an end around way to insert raw lines of config for front ends and backends. Use them sparingly but use them if you need them.

TODO

• thrown exceptions are are not handled in api.js and dependencies
• remove health checks/roles/version leftover from Aqea