Retrieve the host port, of a container launched from Docker SDK for Python-CodePudding

When I launch a container using the docker SDK for Python, I can specify the host port as None so that the SDK will pick a random available port for me:

import docker
client = docker.from_env()

container = client.containers.run(
  "bfirsh/reticulate-splines",
  ports={6379 : None} # SDK chooses a host port
  detach=True)

The problem is that I want to know after the run command which host port did the SDK choose. How do I do that?

CodePudding user response：

You need to reload the container then use container.ports

import docker

client = docker.from_env()

container = client.containers.run(
    "bfirsh/reticulate-splines", ports={6379: None}, detach=True
)

container.reload() # need to reload

print(container.ports)

Output

{'6379/tcp': [{'HostIp': '0.0.0.0', 'HostPort': '53828'}]}

This is only in version greater than 4.0.2 (which is at least 4 years old now)

Commit that added this attribute

CodePudding user response：

Unfortunately a Container object does not have a ports attribute (prior to 3.7.2 as @python_user notes). By printing the attrs dictionary I was able to find out that the host port is contained inside the NetworkSettings attribute. In my case retrieving the host port looks like this:

attrs['NetworkSettings']['Ports']['6379/tcp'][0]['HostPort']
# container port specified at launch ^^^

A more general solution would be to avoid the container port (6379) and search for the 'HostPort' key instead.