This article will illustrate the following content:
- What is Docker Commit?
- What are the Different Options for Docker Commit Command?
- How to Commit a Docker Container?
- How to Commit a Docker Container with New Configurations (–change)?
What is Docker Commit?
Docker commit is a command in Docker that permits users to create a new image from a particular container’s modifications. It is helpful when users want to save the state of a container as a reusable image, or when they want to customize an existing image for their own purposes. The syntax is provided below:
Syntax:
What are the Different Options for Docker Commit Command?
The common options used for Docker commit command are given below:
| Name | Shorthand | Description |
| –author | -a | It is used to specify the author’s name e.g., Laiba <[email protected]>. |
| –change | -c | It applies Docker file instructions to the created image. |
| –message | -m | It is used for the commit message. |
| –pause | -p | It pauses the container during the commit process. |
How to Commit a Docker Container?
To commit a Docker container, follow the below-provided steps:
- List all Docker images.
- Select the specific Docker image.
- Build the container from the selected image and access it.
- Make some changes in the running container.
- Commit changes to the new image using the “docker commit <container-name/ID> <new-image-name>” command.
- Verification
Step 1: Display All Docker Images
First, list available Docker images and select the desired image:
In the above screenshot, all the Docker images can be seen. We have selected the “nginx” image.
Step 2: Build and Access Container
To build and start the Docker container from the Docker image, execute the below-provided command:
Here:
- “-it” flag is used to start the interactive terminal session within the container.
- “–name” sets the name of the container to “nginxCont”.
- “nginx” is the Docker image to use for the container.
- “bash” is utilized to start the bash shell in the container:
The bash of the Nginx container has opened.
Step 3: Make Changes in Container
Next, make some modifications to the running container. For instance, we have created a new file named “test.txt” file with some content:
The output shows that the “test.txt” file has been created with relevant content.
Step 4: Verification
To verify whether the file has been created or not, list all the container’s content using the “ls” command and then execute the “cat <file-name>” command to view the file’s content:
cat test.txt
The above output shows that the “test.txt” file has been created and its content can also be seen.
Step 5: Commit Changes
After that, keep the current container running and open a new terminal. Then, run the “docker commit <container-name> <new-image-name>” command to save modifications to a new image:
Step 6: Verification
To verify whether the changes have been saved to the new image or not, display all Docker images:
In the above output, the new image i.e., “nginx-img” with tag “V1.0” has been created successfully with recent changes.
How to Commit a Docker Container with New Configurations (–change)?
To commit a Docker container with the new configuration, utilize the “docker commit –change “ENV DEBUG=true” <container-name/ID> <new-image-name>” command. For verification, the “docker inspect -f “{{ .Config.Env }}” <new-image-name>” command is used.
Step 1: Commit Container with Configuration
To commit a particular container with configuration, utilize the “–change” option with the “docker commit” command and specify the desired configurations:
Step 2: Verification
To ensure that the commit has been made with the desired configuration or not, execute the below-provided command:
The above output indicates that the commit has been made successfully with the specified configurations.
Conclusion
Docker commit is a Docker command that creates a new image from the modifications made to an existing container. It permits users to capture the current state of a container and save it as a new image that can be utilized to create a similar container in the future. The syntax of the Docker commit command is “docker commit [OPTIONS] <container-name/ID> <new-image-name>”. This article has explained Docker commit, its options, and the method of committing a container.
