I am using Python to start docker instances.

How can I identify if they are running? I can pretty easily use docker ps from terminal like:

docker ps | grep myimagename

and if this returns anything, the image is running. If it returns an empty string, the image is not running.

However, I cannot understand how to get subprocess.Popen to work with this - it requires a list of arguments so something like:

    p = subprocess.Popen(['docker', 'ps', '|', 'grep', 'myimagename'], stdout=subprocess.PIPE)print p.stdout

does not work because it tries to take the "docker ps" and make it "docker" and "ps" commands (which docker doesn't support).

It doesn't seem I can give it the full command, either, as Popen tries to run the entire first argument as the executable, so this fails:

    p = subprocess.Popen('docker ps | grep myimagename', stdout=subprocess.PIPE)print p.stdout

Is there a way to actually run docker ps from Python? I don't know if trying to use subprocess is the best route or not. It is what I am using to run the docker containers, however, so it seemed to be the right path.

• How can I determine if a docker instance is running from a Python script?

You can use the python docker client:

import docker
DOCKER_CLIENT = docker.DockerClient(base_url='unix://var/run/docker.sock')
RUNNING = 'running'def is_running(container_name):"""verify the status of a sniffer container by it's name:param container_name: the name of the container:return: Boolean if the status is ok"""container = DOCKER_CLIENT.containers.get(container_name)container_state = container.attrs['State']container_is_running = container_state['Status'] == RUNNINGreturn container_is_runningmy_container_name = "asdf"
print(is_running(my_container_name))