How to use docker config rm command to remove configs

Introduction

In this lab, we will explore how to manage configuration data within a Docker Swarm environment using Docker configs. We will begin by learning how to create a Docker Swarm config from a file, which allows services to securely access configuration information.

Following the creation of a config, we will cover how to list existing Docker Swarm configs to view their details. Finally, the core focus of this lab will be on demonstrating how to remove Docker Swarm configs, both by their name and by their unique ID, using the docker config rm command.

Skills Graph

Create a Docker Swarm config

In this step, we will learn how to create a Docker Swarm config. A Docker Swarm config is a configuration object that can be used by services to inject configuration data into tasks. This is useful for managing application configurations without rebuilding service images.

First, let's create a simple configuration file. We will create a file named my_config.txt in the ~/project directory with some sample configuration data.

echo "This is my sample configuration data." > ~/project/my_config.txt

Now, we can create a Docker Swarm config from this file using the docker config create command. The basic syntax is docker config create <config_name> <file_path>.

docker config create my_app_config ~/project/my_config.txt

This command creates a new Docker Swarm config named my_app_config using the content of the ~/project/my_config.txt file. You should see the ID of the newly created config in the output.

To verify that the config has been created, you can list the existing configs using the docker config ls command.

docker config ls

You should see my_app_config listed in the output.

List existing Docker Swarm configs

In this step, we will learn how to list existing Docker Swarm configs. This is a simple but essential operation to see what configurations are available in your Swarm.

To list all existing Docker Swarm configs, you use the docker config ls command. This command will display a table with information about each config, including its ID, name, and creation date.

docker config ls

You should see the my_app_config that we created in the previous step listed in the output. The output will look similar to this:

ID          NAME            CREATED
<config_id> my_app_config   <creation_date>

The <config_id> will be a unique identifier for your config, and <creation_date> will be the date and time it was created.

This command is useful for quickly checking the names and IDs of your configs, which you will need for other operations like removing a config.

Remove a Docker Swarm config by name

In this step, we will learn how to remove a Docker Swarm config using its name. This is a common way to clean up unused configurations.

To remove a Docker Swarm config by its name, you use the docker config rm command followed by the name of the config. The syntax is docker config rm <config_name>.

We will remove the my_app_config that we created in the previous steps.

docker config rm my_app_config

You should see the name of the removed config in the output, confirming that it has been successfully removed.

To verify that the config has been removed, you can list the existing configs again using the docker config ls command.

docker config ls

This time, my_app_config should no longer appear in the list.

Remove a Docker Swarm config by ID

In this step, we will learn how to remove a Docker Swarm config using its ID. While removing by name is often more convenient, removing by ID is useful when you have multiple configs with similar names or need to be absolutely sure which config you are removing.

First, let's create another config so we have something to remove by ID. We'll create a file named another_config.txt and then create a config from it.

echo "This is another sample configuration data." > ~/project/another_config.txt
docker config create another_app_config ~/project/another_config.txt

Now, list the configs to get the ID of another_app_config.

docker config ls

Look for the another_app_config in the output and note its ID. The ID will be a string of characters.

To remove a Docker Swarm config by its ID, you use the docker config rm command followed by the ID of the config. The syntax is docker config rm <config_id>.

Replace <config_id> with the actual ID you noted from the previous command's output.

docker config rm <config_id>

For example, if the ID was abcdef123456, the command would be:

docker config rm abcdef123456

You should see the ID of the removed config in the output, confirming its removal.

Finally, list the configs again to verify that another_app_config is no longer present.

docker config ls

Summary

In this lab, we learned how to manage Docker Swarm configurations. We started by creating a configuration object from a local file using the docker config create command, which allows services to access configuration data without modifying their images. We then practiced listing existing configurations using docker config ls to verify their creation and view their details.

The lab also covered how to remove Docker Swarm configurations. We learned to remove a config by its name using docker config rm <config_name> and by its unique ID using docker config rm <config_id>. These steps demonstrated the complete lifecycle of managing configurations within a Docker Swarm environment.