Docker Commands

The Docker provider exposes some additional Vagrant commands that are useful for interacting with Docker containers. This helps with your workflow on top of Vagrant so that you have full access to Docker underneath.

docker-exec

vagrant docker-exec can be used to run one-off commands against a Docker container that is currently running. If the container is not running, an error will be returned.

$ vagrant docker-exec app -- rake db:migrate

The above would run rake db:migrate in the context of an app container.

Note that the "name" corresponds to the name of the VM, not the name of the Docker container. Consider the following Vagrantfile:

Vagrant.configure(2) do |config|
  config.vm.provider "docker" do |d|
    d.image = "consul"
  end
end

This Vagrantfile will start the official Docker Consul image. However, the associated Vagrant command to docker-exec into this instance is:

$ vagrant docker-exec -it -- /bin/sh

In particular, the command is actually:

$ vagrant docker-exec default -it -- /bin/sh

Because "default" is the default name of the first defined VM. In a multi-machine Vagrant setup as shown below, the "name" attribute corresponds to the name of the VM, not the name of the container:

Vagrant.configure do |config|
  config.vm.define "web" do
    config.vm.provider "docker" do |d|
      d.image = "nginx"
    end
  end

  config.vm.define "consul" do
    config.vm.provider "docker" do |d|
      d.image = "consul"
    end
  end
end

The following command is invalid:

# Not valid
$ vagrant docker-exec -it nginx -- /bin/sh

This is because the "name" of the VM is "web", so the command is actually:

$ vagrant docker-exec -it web -- /bin/sh

For this reason, it is recommended that you name the VM the same as the container. In the above example, it is unambiguous that the command to enter the Consul container is:

$ vagrant docker-exec -it consul -- /bin/sh

docker-logs

vagrant docker-logs can be used to see the logs of a running container. Because most Docker containers are single-process, this is used to see the logs of that one process. Additionally, the logs can be tailed.

docker-run

vagrant docker-run can be used to run one-off commands against a Docker container. The one-off Docker container that is started shares all the volumes, links, etc. of the original Docker container. An example is shown below:

$ vagrant docker-run app -- rake db:migrate

The above would run rake db:migrate in the context of an app container.