Working with docker context

Photo by Ian Taylor on Unsplash

What are docker contexts?

Let’s explain this concept with an easy example. You work in an enterprise where there are two different cluster: the develop and the production one. You have to mange (publish, see logs…) on both two clusters accordingly with your work. Each cluster represents a “context” switching the context you can issue docker commands on the different cluster.

To switch (change) the context you are operating on you can use this command:

$ docker context use <context-name>

A context is made up of these properties:

• Name
• Endpoint configuration
• TLS info
• Orchestrator

when you install docker it creates a default context, you can inspect it with:

$ docker context ls
NAME         DESCRIPTION                               DOCKER ENDPOINT                 KUBERNETES ENDPOINT      ORCHESTRATOR
default *    Current ...                               unix:///var/run/docker.sock                              swarm

Create a context doing something like this:

$ docker context create docker-dev-host \
   --default-stack-orchestrator=swarm \
   --docker host=ssh://user@192.168.1.100

Dockercon

dockercon is a tool to switch between docker contexts faster. It also allows you to create context faster.

GitHub - corradoignoti/dockercon: dockercon is a tool to switch between docker contexts faster.

To add a context:

$ dockercon -a mydockerhst-local --host ssh://user@192.168.1.1 --stack swarm

To switch context:

$ dockercon mydockerhst-local
mydockerhst-local
Current context is now "mydockerhst-local"
is now the dafult context

To see the saved context:

$ dockercon
NAME         DESCRIPTION                               DOCKER ENDPOINT                 KUBERNETES ENDPOINT      ORCHESTRATOR
default *    Current ...                               unix:///var/run/docker.sock                              swarm

Hope you enjoy!