Managing Docker Contexts

This post will cover topic related to ‘Managing Docker Contexts’ with multiple docker command examples and different scenerios. So this will help you to understand the command docker and options available in it. Also this post will explain you how to use docker command.

Docker contexts allow users to manage different Docker environments seamlessly. Each context represents a different Docker endpoint, such as a local Docker daemon, a remote Docker host, or a cloud-based Docker instance. This capability is especially useful for developers and operators who work with multiple Docker environments and need to switch between them efficiently.

Example 1: Listing Docker Contexts
To list all available Docker contexts, use the following command:

docker context ls

This command displays a table listing all defined contexts along with their current statuses.

        NAME                DESCRIPTION         DOCKER ENDPOINT                 KUBERNETES ENDPOINT   ORCHESTRATOR
        default *           Current DOCKER CLI   unix:///var/run/docker.sock                         swarm
        remote              Remote Docker       ssh://user@remote-host
        aws                 AWS Cloud Docker    https://aws.example.com
        

To verify, execute the command and check the output for the list of contexts.

Example 2: Using a Specific Docker Context
To switch to a specific Docker context for subsequent commands, use:

docker context use aws

This command switches the Docker CLI to use the context named ‘aws’, enabling commands to interact with Docker on AWS.

Verify by running a Docker command that interacts with AWS Docker resources.

Example 3: Creating a New Docker Context
To create a new Docker context for a remote Docker host, use:

docker context create remote --docker "host=ssh://user@remote-host"

This command defines a new context named ‘remote’ with the specified SSH endpoint for the Docker host.

Verify by listing contexts and checking if ‘remote’ appears in the list.

Example 4: Removing a Docker Context
To delete a Docker context, use:

docker context rm remote

This command removes the ‘remote’ context from the Docker CLI configuration.

Verify by listing contexts again to confirm ‘remote’ is no longer listed.

Example 5: Inspecting Details of a Docker Context
To inspect detailed information about a specific Docker context, use:

docker context inspect aws

This command provides a JSON-formatted output detailing the configuration of the ‘aws’ context.

Verify by reviewing the JSON output to ensure it contains relevant details.

Example 6: Exporting a Docker Context Configuration
To export the configuration of a Docker context to a file, use:

docker context export aws > aws-context.json

This command exports the ‘aws’ context configuration to a JSON file named ‘aws-context.json’.

Verify by inspecting the generated JSON file for correctness and completeness.

Example 7: Importing a Docker Context Configuration
To import a previously exported Docker context configuration from a file, use:

docker context import aws-new < aws-context.json

This command imports the context configuration stored in ‘aws-context.json’ to create a new context named ‘aws-new’.

Verify by listing contexts and checking if ‘aws-new’ appears.

Example 8: Switching Docker Contexts with a Shell Command
To switch Docker context within a shell session, use:

eval $(docker context env aws)

This command sets environment variables to use the ‘aws’ context for subsequent Docker commands.

Verify by executing Docker commands and ensuring they interact with AWS resources.

Example 9: Using Docker Contexts with Kubernetes
To switch the Kubernetes context along with Docker context, use:

docker context use aws --kubernetes

This command switches both Docker and Kubernetes contexts to ‘aws’ for integrated management.

Verify by listing Kubernetes contexts to ensure the ‘aws’ context is active.

Example 10: Renaming a Docker Context
To rename an existing Docker context, use:

docker context rename aws aws-new-name

This command renames the context ‘aws’ to ‘aws-new-name’ while preserving its configuration.

Verify by listing contexts and checking if ‘aws-new-name’ appears with the updated configuration.

Also check similar articles.

Managing Docker Containers
Managing Docker Checkpoints
Managing Docker Builds
Searching Docker Hub for Images
Logging out from Docker Registries