Docker Dispatch

Why?

Some applications have a need to create a collection of containers via a reliable stream of queued messages.

Architecture

Docker dispatch listens for properly formatted messages from RabbitMQ and creates/runs containers from pre-built images in Docker. It talks to the Docker daemon via its RESTful API and delivers responses in stdout.

Demo

Install

Fetch repository:

$ go get github.com/mutaphore/docker-dispatch

Build:

$ cd $GOPATH/github.com/mutaphore/docker-dispatch
$ go build

Run

To run the dispatcher service:

$ ./docker-dispatch [options] dockerHostAddr amqpAddr

dockerHostAddr is the docker daemon host address you would like the dispatcher to connect to. This can be expressed as a TCP url or the socket path. A valid TCP url would have ip:port format such as 172.17.0.1:2375. A socket path is the unix file path to the socket which is usually like /var/run/docker.sock. Information on how to configure and run the Docker daemon can be found here

amqpAddr is the full url to RabbitMQ with format amqp://username:password@host:port. Here's the full spec. For example, a valid url would be something like amqp://guest:guest@localhost:5672/

Example:

./dockerdispatch -q myqueue 172.17.0.1:2375 amqp://guest:guest@localhost:5672

For more information on how to setup Docker to bind to different addresses see here.

Message formats

Docker dispatcher accepts JSON messages similar to the CLI command that you would give to the docker daemon. Note: all JSON keys are capitalized.

Running a container from an image (docker run)

• Dockercmd - docker command to execute: "run"
• Options - object containing options to pass into the docker command.
  • Name - name of container
  • Entrypoint - command to execute in container
  • Attach - attach to container file descriptors that is an array of strings selected from "STDIN", "STDOUT", "STDERR"
  • Remove - automatically remove the container when it exits
• Image - image name to create container from
• Cmd - exec form of command to run in container having format ["executable","param1","param2"]

Example

{
  Dockercmd: "run",
  Options: {
    Name: "hello_world",
    Attach: ["STDOUT", "STDERR"],
    Remove: true
  },
  Image: "debian:jessie"
  Cmd: ["echo", "hello world!"]
}

Stopping a container (docker stop)

• Dockercmd - docker command to execute: "stop"
• Options - object containing options to pass into the docker command.
  • Time - seconds to wait for stop before killing it (default 10)
• Container - name or id of container to remove

Example

{
  Dockercmd: "stop",
  Options: {
    Time: 5
  },
  Container: "hello_world"
}

Removing a container (docker rm)

• Dockercmd - docker command to execute: "remove"
• Options - object containing options to pass into the docker command.
  • Volumes - remove the volumes associated with the container
  • Force - force the removal of a running container (uses SIGKILL)
• Container - name or id of container to remove

Example

{
  Dockercmd: "remove",
  Container: "hello_world"
}