How-to: Control containers

Overview

This example illustrates how the Docker plugin can be used to control a Docker container, as part of the container creation or destruction.

Extension of another example

This example modifies the container configuration example How-to: Configure Docker containers (Exposed ports).

Please consult that example for details about Pineapple configuration, modules and models describes how Pineapple can be used to install Docker on a Vagrant box for the purpose of the example.

Define the module model

The model file for definition of the image and the container:

<?xml version="1.0" encoding="UTF-8" standalone="yes"?>
<mmd:models xmlns:mmd="http://pineapple.dev.java.net/ns/module_model_1_0"       
    xmlns:dkp="http://pineapple.dev.java.net/ns/plugin/docker_1_0" continue="false" >
  <mmd:model target-resource="docker-node" target-operation="deploy-configuration" description="Define Docker image: busybox:latest" >
    <mmd:content>
      <dkp:docker>
        <dkp:image repository="busybox" tag="latest" />
      </dkp:docker>                       
    </mmd:content>
  </mmd:model>
  <mmd:model target-resource="docker-node" description="Define Docker container alpha01" >
    <mmd:content>
      <dkp:docker>
        <dkp:container name="alpha01" state="running" >
          <dkp:image repository="docker.io/busybox" tag="latest" />
        </dkp:container>        
      </dkp:docker>                       
    </mmd:content>
  </mmd:model>
</mmd:models>

The configuration details

Definition of a container

The second model contains the dkp:container element which defines a Docker container. When the model is invoked with the deploy-configuration operation then the container is created. When the model is invoked with the undeploy-configuration operation then the container is deleted.

Controlling a container

The container element contains an optional state attribute. The attribute defines which state the container should be put in when the model is invoked with a deploy-configuration operation, i.e. when the container is created.

The attribute is used in this example to start the container by putting it into the running state. 

  <dkp:container name="alpha01" state="running" >

The state attribute supports three states:

  • running - the container is started. The container can be paused or stopped.
  • stopped - the container is stopped. The container can be started.
  • paused - the container have been started and is now paused. The container can be started or stopped.

When the model is invoked with a undeploy-configuration operation then a container handled a bit differently depending on its state:

  • If the container is running then container is stopped and then deleted.
  • If the container is stopped then container is deleted.
  • If the container is paused then container is un-paused (i.e. started), stopped and then deleted.