dockit

Orchestrating docker with go

This is not supposed to be a general-purpose tool, but an example of how wiring up Docker environments using go is...

• Testable: a testing framework is built in
• Easy to read: idiomatic style that is almost universally followed making for a terse, highly readable ecosystem
• Easy to maintain: I'm assuming you were doing this work in bash before
• Portable: really, we're only talking about Linux with Docker, so a single statically linked binary is as portable as you can get

So get some ideas here (or use this as a starting point) and go build your own toolkit to codify (no pun intended) the conventions, opinions, and nuances of your environment in a format which you can maintain.

Usage

By default, dockit looks for a config.json file in your current directory, connects using unix:///var/run/docker.sock, and keeps track of running containers with "pid" files in /var/run/dockit-containers.

You can define services for your environment in the config file, and specify ports, environment variables, and dependancy services (which are translated into links.)

Example Environment

Included in this repo, is an example config to build an environment with a webapp (the included webapp-ex/) fronted by a reverse proxy (Hipache.)

The config specifies:

• the webapp ("WebApp" service) container should link in the hipache/redis ("Hipache" service) container
• which ports to expose (in the link and externally)
• an environment variable for the webapp to use as a host name when registering with Hipache

The webapp entry point script (webapp-ex/start.sh) uses the link and host env var to register the webapp with Hipache and to deregister on shutdown.

Here is a copy of config.json from our example environment:

{"Hipache" : {
	"Image" : "stackbrew/hipache",
	"Ports" : {
		"80" : "80",
		"6379" : ""
	}
	
}, "WebApp" : {
	"Image" : "benschw/go-webapp",
	"Deps" : [
		"Hipache"
	],
	"Env" : {
		"HOST" : "webapp.local"
	}
}}

(the image benschw/go-webapp was built from the contents of the webapp-ex directory)

Run the example

sudo ./dockit -service WebApp -start

This will start up the WebApp service (bringing Hipache up too as it is a dependency) and register the private ip:port of the WebApp container with Hipache (see webapp-ex/start.sh) under the name webapp.local.

add 127.0.0.1 webapp.local to your /etc/hosts file and the example webapp should be available on at http://webapp.local

Stop the example

sudo ./dockit -service WebApp -stop

This will only stop the WebApp container (and deregister from Hipache); Hipache is still running. To stop it too, run:

sudo ./dockit -service Hipache -stop

Note the containers are still there in a "stopped" state, and that a subsequent -start will run new instances.