helmer

Node Implementation of Foreman

npm install helmer
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Helmer

Helmer is a bleeding edge fork of Node Foreman a Node.js version of the popular Foreman tool, with a few Node specific changes.

Foreman is a manager for Procfile-based applications. Its aim is to abstract away the details of the Procfile format, and allow you to either run your application directly or export it to some other process management format.

Install

Install the command line tool

$ npm install -g helmer

All of Foremans version dependencies have been set to use latest. If however you find a dependency should break it is possible to find out which dependency versions were last working with Foreman. The npm-shrinkwrap.json file is updated each time Foreman is published to npm.

How to Contribute

I encourage anyone and everyone to help. If you have a specific change in mind, open an issue; we can talk about it there.

If you would like to make a code change, go ahead. Fork the repository, open a pull request. Do this early, and talk about the change you want to make. Maybe we can work together on it.

Refactor Refactor Refactor! You are free to add features, or just help clean things up.

Usage

Node Foreman can be run with as little as helmer start, as long as npm start has been defined. For more complicated applications you will want to define a Procfile for your various server processes and and a .env file to preload environmental variables.

Your module directory should end up looking like the following:

List Foreman Directory

Once your Procfile is defined, run your application with helmer start:

Start Foreman

Node Foreman always starts in the foreground and expects your applications to do the same. If your processes exit, Node Foreman will assume an error has ocurred and shut your application down.

Instead of daemonizing, you should use helmer export to ready your application for production.

For more information try any of the following:

$ helmer --help
$ helmer start --help
$ helmer export --help

Procfile

The Procfile format is a simple key : command format:

web: node web_server.js
api: node api_server.js
log: node log_server.js

Each line should contain a separate process.

Environmental Variables

Create a .env file to pre-load environmental variables with the format:

MYSQL_NAME=superman
MYSQL_PASS=cryptonite

The equivalent .env file may alternatively be a valid JSON document:

{
    "mysql":{
        "name": "superman",
        "pass": "cryptonite"
    }
}

The above JSON document will be flattened into env variables by concatenating the nested values with an underscore. Environmental variables are passed in fully capitalized.

{
    "mysql":{
        "name": "superman",     # => MYSQL_NAME=superman
        "pass": "cryptonite"    # => MYSQL_PASS=cryptonite
    }
}

There is no need to specify which type of file you wish to use.

The PATH environment variable

The PATH variable is given special treament and is always read from the environment that the nf command has been executed from, rather than a .env file. To set a different PATH execute nf with the PATH variable set appropriately.

PATH=/opt/foo:/opt/bar:$PATH helmer export

Best Practices

Generally you should not check your .env file into version control. The .env file contain only parameters that depend on where the application gets deployed. It should not contain anything related to how the application is deployed.

For example, good candiates for the .env file are MySQL connection information, port bindings, and other passwords.

Advanced Usage

Node Foreman lets you start multiple jobs of the same type:

$ helmer start web=5

18:51:12: web.1     |  Web Server started listening on 0.0.0.0:5000
18:51:12: web.2     |  Web Server started listening on 0.0.0.0:5001
18:51:12: web.3     |  Web Server started listening on 0.0.0.0:5002
18:51:12: web.4     |  Web Server started listening on 0.0.0.0:5003
18:51:12: web.5     |  Web Server started listening on 0.0.0.0:5004

Each job will be started as its own process, receiving a different PORT environmental variable. The port number for processes of the same type will be offset by 1. The port number for processes of different types will be offset by 100.

$ helmer start web=2,api=2

18:51:12: web.1     |  Web Server started listening on 0.0.0.0:5000
18:51:12: web.2     |  Web Server started listening on 0.0.0.0:5001
18:51:12: api.1     |  Api Server started listening on 0.0.0.0:5100
18:51:12: api.2     |  Api Server started listening on 0.0.0.0:5101

Export to Production

Node Foreman is designed to be in a development environment, however it can export an Upstart job for use in production. The Upstart file has no dependency on Node Foreman.

$ helmer export
Loaded ENV .env File as JSON Format
Wrote  :  ./foreman-web-1.conf
Wrote  :  ./foreman-web.conf
Wrote  :  ./foreman-api-1.conf
Wrote  :  ./foreman-api.conf
Wrote  :  ./foreman-log-1.conf
Wrote  :  ./foreman-log.conf
Wrote  :  ./foreman.conf

You can inspect your upstart files before placing them in the right directory, or have foreman do it for you:

$ sudo helmer export -o /etc/init
Loaded ENV .env File as JSON Format
Wrote  :  /etc/init/foreman-api-1.conf
Wrote  :  /etc/init/foreman-web.conf
Wrote  :  /etc/init/foreman-api.conf
Wrote  :  /etc/init/foreman-log.conf
Wrote  :  /etc/init/foreman-log-1.conf
Wrote  :  /etc/init/foreman-web-1.conf
Wrote  :  /etc/init/foreman.conf

Start and stop your jobs with

$ sudo start foreman
$ sudo stop foreman

The export will occur with whatever environmental variables are listed in the .env file.

Systemd Support

This section is beta

Optionally specify a type -t systemd during export for systemd support.

Advanced Exports

You can specify the type and number of processes exported using the type=num syntax:

$ helmer export web=2,api=2

Use -u <USER> to have the exported job run as USER. Note that if you need to bind to privileged ports, you must start as root. In such a case, we advise you to drop user permissions after binding.

If you want to call your upstart job something other than foreman, use -a <JOBNAME> and manage your jobs with sudo start <JOBNAME>.

Reverse Proxy

Node.js processes are supposed to be stateless. Application scale by starting multiple processes that either share a socket, or sit behind a load balancer. Node Foreman can help you test the parallel capabilities of your application by spawning multiple processes behind a round-robin proxy automatically.

$ helmer start -x 8888 web=5
[OKAY] Starting Proxy Server 8888 -> 5000-5004

Access your application from port 8888 and the connections will be balanced across the servers started from ports 5000 - 5004.

If your application gets its port number from process.env.PORT the proxy setup will ocurr automatically.

Multiple Reverse Proxies

If you have multiple processes in your Procfile you can start multiple proxies.

$ helmer start -x 8888,8080,9090

This will start 3 separate proxies and bind each to a separate process group. Proxies are bound based on their order specified, their order in the Procfile, or by their order on the command line.

$ helmer start -x 8888,9999 web,api

Privileged Ports

Node Foreman disallows applications from starting on privileged ports. It does however allow proxies to be bound to lower ports, such as port 80.

If you require access to a privileged port, start Node Foreman with sudo:

$ sudo helmer start -x 80 web=5
[OKAY] Starting Proxy Server 80 -> 5000-5004

Your application will then be accessible via port 80.

Your applications will still be started in user space, and the proxy will drop its privileges after binding to the privileged port.

Forward Proxy

Local development and testing has huge advantages, but sometimes one needs to test web applications agains their real-world domain name. Editing /etc/hosts is a pain however, and error prone.

Node Foreman can start up an HTTP forward proxy which your browser can route requests through. The forward proxy will intercept requests based on domain name, and route them to the local application.

$ helmer start -f 9999 -h nodefly.com
[OKAY] Forward Proxy Started in Port 9999
[OKAY] Intercepting requests to nodefly.com through forward proxy

A forward proxy is useful when testing OAuth, or other external services with application callbacks.

For users with Google Chrome, this can be paired with Proxy Switch Sharp for great results.

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