How to use docker desktop module ls command to list modules

Introduction

In this lab, you will learn how to list Docker Desktop modules using the docker version command. We will explore different ways to view this information, including listing all modules, displaying the output in JSON format, and extracting only the module IDs. This hands-on exercise will help you understand the components of your Docker installation and how to retrieve information about them.

List all Docker Desktop modules

In this step, we will learn how to list all the Docker Desktop modules using the docker version command. The docker version command provides detailed information about the Docker installation, including the client and server components, and the modules that are part of the Docker Desktop installation.

To list all the Docker Desktop modules, open your terminal and run the following command:

docker version

This command will output a lot of information about your Docker installation. Look for sections like Client and Server. Within these sections, you will find details about various components and modules.

For example, the output might look something like this (the exact output may vary depending on your Docker version and installation):

Client: Docker Engine - Community
 Version:           20.10.21
 API version:       1.41
 Go version:        go1.16.15
 Git commit:        f2213a1
 Built:             Thu Oct 27 00:18:36 2022
 OS/Arch:           linux/amd64
 Context:           default
 Experimental:      true

Server: Docker Engine - Community
 Engine:
  Version:          20.10.21
  API version:      1.41 (minimum version 1.12)
  Go version:       go1.16.15
  Git commit:       3056e8c
  Built:            Thu Oct 27 00:17:23 2022
  OS/Arch:          linux/amd64
  Experimental:     false
 containerd:
  Version:          1.6.8
  GitCommit:        9cd358bba7fd9c7bb19904ba6d2f58fd60b1ca2b
 runc:
  Version:          1.1.4
  GitCommit:        v1.1.4-0-g5fd4c4d
 docker-init:
  Version:          0.19.0
  GitCommit:        de40ad0

In this output, you can see information about the Docker Engine, containerd, runc, and docker-init. These are some of the key modules that make up the Docker environment. The docker version command is a useful tool for understanding the different components of your Docker installation and their versions.

List Docker Desktop modules in JSON format

In the previous step, we used the docker version command to list the Docker Desktop modules. The default output is human-readable, but sometimes you might need the output in a structured format, like JSON, for scripting or further processing.

The docker version command supports a --format flag that allows you to specify the output format using Go's text/template package. To get the output in JSON format, you can use the json . template.

Run the following command in your terminal:

docker version --format '{{json .}}'

This command will output the same information as docker version, but formatted as a JSON object. The {{json .}} part is the template that tells Docker to format the entire output (.) as JSON.

The output will be a single line of JSON data, which might look something like this (formatted for readability):

{
  "Client": {
    "Version": "20.10.21",
    "ApiVersion": "1.41",
    "GoVersion": "go1.16.15",
    "GitCommit": "f2213a1",
    "Built": "Thu Oct 27 00:18:36 2022",
    "OsArch": "linux/amd64",
    "Context": "default",
    "Experimental": true
  },
  "Server": {
    "Engine": {
      "Version": "20.10.21",
      "ApiVersion": "1.41",
      "MinAPIVersion": "1.12",
      "GoVersion": "go1.16.15",
      "GitCommit": "3056e8c",
      "Built": "Thu Oct 27 00:17:23 2022",
      "OsArch": "linux/amd64",
      "Experimental": false
    },
    "Containerd": {
      "Version": "1.6.8",
      "GitCommit": "9cd358bba7fd9c7bb19904ba6d2f58fd60b1ca2b"
    },
    "Runc": {
      "Version": "1.1.4",
      "GitCommit": "v1.1.4-0-g5fd4c4d"
    },
    "DockerInit": {
      "Version": "0.19.0",
      "GitCommit": "de40ad0"
    }
  }
}

This JSON output contains the same information as the default output, but in a structured format that is easy for programs to parse. This is particularly useful when you want to extract specific pieces of information from the docker version output in scripts.

List only the IDs of Docker Desktop modules

In the previous steps, we learned how to list all Docker Desktop modules and how to format the output as JSON. Now, let's explore how to extract only specific information, such as the Git commit IDs of the modules. This is useful when you only need a particular piece of data for scripting or automation.

We can again use the --format flag with a custom template to achieve this. By inspecting the JSON output from the previous step, we can see that the Git commit IDs are located under Server.Engine.GitCommit, Server.Containerd.GitCommit, Server.Runc.GitCommit, and Server.DockerInit.GitCommit.

We can construct a template to extract these specific fields. Run the following command in your terminal:

docker version --format 'Engine GitCommit: {{.Server.Engine.GitCommit}}\nContainerd GitCommit: {{.Server.Containerd.GitCommit}}\nRunc GitCommit: {{.Server.Runc.GitCommit}}\nDockerInit GitCommit: {{.Server.DockerInit.GitCommit}}'

Let's break down the template:

• Engine GitCommit: {{.Server.Engine.GitCommit}}: This part extracts the GitCommit value from the Engine object within the Server object.
• \n: This adds a newline character to separate the output for each module.
• Containerd GitCommit: {{.Server.Containerd.GitCommit}}: Extracts the GitCommit for containerd.
• Runc GitCommit: {{.Server.Runc.GitCommit}}: Extracts the GitCommit for runc.
• DockerInit GitCommit: {{.Server.DockerInit.GitCommit}}: Extracts the GitCommit for docker-init.

The output will show the Git commit ID for each specified module, similar to this:

Engine GitCommit: 3056e8c
Containerd GitCommit: 9cd358bba7fd9c7bb19904ba6d2f58fd60b1ca2b
Runc GitCommit: v1.1.4-0-g5fd4c4d
DockerInit GitCommit: de40ad0

This demonstrates the power of the --format flag and Go templates for extracting specific data from Docker commands. You can customize the template to extract any field available in the docker version output.

Summary

In this lab, we learned how to list Docker Desktop modules using the docker version command. We explored how to display all modules and their details, which provides valuable information about the different components of the Docker installation, such as the Docker Engine, containerd, runc, and docker-init, along with their versions.

We also learned how to list Docker Desktop modules in JSON format, which is useful for programmatic processing and integration with other tools. Finally, we covered how to list only the IDs of the Docker Desktop modules, providing a concise output for quick identification.