Docker Context for remote host management

[shantanoo-desai]

SUMMARY

Since Docker v18.09+ it is possible to use the same docker CLI on a Controller Node to get access to remote Managed Nodes. This is generally achieved initially by using docker context create ....

This command is capable enough to work with Docker Swarm, Kubernetes for Orchestration as well for standalone remote nodes over TCP (with / without TLS), as well as SSH.

Thorough Documentation can be found on Docker Docs: Docker Context.

The tool also provides facilities or exporting / importing these created contexts as well as controlling the Docker Containers on Remote nodes.

ISSUE TYPE

• Feature Idea

COMPONENT NAME

community.docker.docker_context

ADDITIONAL INFORMATION

This may be an example module called docker_context:

- name: Create Docker Context for Hosts in Inventory
  community.docker.docker_context:
    name: "ctx-{{ inventory_hostname }}"
    description: "docker context for remote node: {{ inventory_hostname }}"
    state: created
    endpoint: "ssh://{{ inventory_hostname }}"

There are certainly benefits where at least from the CLI, the following examples can perform tasks, which are performed locally, also on a remote machine

# list running docker containers on `my-host-1`

docker --context=ctx-my-host-1 ps -a

In conjuction with docker compose one can deploy a compose application without needing to copy a compose file to the remote machine

# executing in the same directory as `docker-compose.yml`
docker --context=ctx-my-host-1 compose up -d

A well written Docker Post for deploying on Remote Docker Host with docker compose

[felixfontein]

At least docker context ls and docker context inspect have a --format json parameter :)

[shantanoo-desai]

I think docker.py also has an implementation for context.

[shantanoo-desai]

Initial trials with docker-py:

import docker

client = docker.DockerClient(base_url="ssh://<user>@<hostname>", use_ssh_client=True)
client.containers.list() # will show containers on the remote machine

This however requires paramiko to be installed as a pip package to make the use_ssh_client parameter work. I haven't got around with how to use the Context and ContextAPI

[Vladimir-csp]

Would be great if all modules that interact with docker also supported contexts, including default one.

[felixfontein]

#1039 adds a docker_context_info module which allows to extract the config for a context so that it can be used by the modules in this collection.