A Docker-based mini-PaaS

The Why

So by now everyone has heard of Docker right? (If not, you have some catching up to do!)

Why have I created this mini-PaaS based around Docker? What’s wrong with the many myriad of platforms and services out there:

• Tutum
• AWS
• Deis
• Solum
• Flynn

Well. Nothing! The various platforms, services and stacks that exist to service, deploy, monitor applications using Docker all have their use-cases and pros and cons.

If you call the post Flynn vs. Deis: The Tale of Two Docker Micro-PaaS Technologies i said the following about ~10months ago.

I’ve stuck by this and 10 months later here it is.

docker-compose.yml:

autodock:
  image: prologic/autodock
  ports:
    - "1338:1338/udp"
    - "1338:1338/tcp"
  volumes:
    - /var/run/docker.sock:/var/run/docker.sock

autodocklogger:
  image: prologic/autodock-logger
  links:
    - autodock

autodockhipache:
  image: prologic/autodock-hipache
  links:
    - autodock
    - hipache:redis

hipache:
  image: hipache
  ports:
    - 80:80
    - 443:443

Gist here: https://gist.github.com/prologic/72ca4076a63d5dd1687d

This uses the following tools and software (all which I wrote as well):

• autodock
• autodock-logger
• autodock-hipache
• hipachectl

Now. Here’s the thing. Nothing here is particularly fancy.

• There’s no DNS management
• There’s no fancy services to speak of
• There’s no web interface at all.
• There’s no API or even a CLI tool

So what is there?

Basically this works in a very simple way.

1. Setup a wildcard A record on a domain pointing it at your Docker host.
2. Spin up containers with the -e VIRTUALHOST environment variable.

That’s it!

The How

How this works:

• autodock is a daemon that listens for Docker events via the Docker Remote API
• autodock is pluggable and provides a UDP-based distributed interface to other plugins.
• When autodock sees a Docker event it broadcasts it to all nodes.
• When autodock-hipache sees container start/stop/died/killed/paused/unpaused events it:
  • Checks for a VIRTUALHOST environment variable.
  • Checks for a PORT environment variable (optional, default: 80).
  • Checks the configuration of the container for exposed ports.
  • If PORT is a valid exposed port; reconfigure hipache with the provided virtualhost from the VIRTUALHOST environment variable routing web requests to the container’s ip address and port given by PORT.

Usage

Using this is quite simple. Copy the above docker-compose.yml and run:

$ docker-compose up -d

Then start a container:

$ docker run -d -e VIRTUALHOST=hello.local prologic/hello

And visit: http://hello.local

Assuming (of course) hello.local points to your Docker host in /etc/hosts.

Of course real deployments of this will use real domains and a real DNS server.

Two example deployments of this can be seen here:

• http://hello.vz1.bne.shortcircuit.net.au/
• http://hello.vallinux.org/

Enjoy! :)

Update: I have now created a new project/tool to help facilitate the setup of this little minimal PaaS. Check out autodock-paas!