Скачать или смотреть How to Start a Docker Container in User Mode with Read-Write Access

Learn how to configure your Docker container to allow non-root users to have `read-write access` for creating files and folders. A step-by-step guide to managing permissions and user management in Docker containers.
---
This video is based on the question https://stackoverflow.com/q/63077264/ asked by the user 'HW_Tang' ( https://stackoverflow.com/u/7820771/ ) and on the answer https://stackoverflow.com/a/63077458/ provided by the user 'Matus Dubrava' ( https://stackoverflow.com/u/9518890/ ) at 'Stack Overflow' website. Thanks to these great users and Stackexchange community for their contributions.

Visit these links for original content and any more details, such as alternate solutions, latest updates/developments on topic, comments, revision history etc. For example, the original title of the Question was: start a docker container in user mode with read-write access permission

Also, Content (except music) licensed under CC BY-SA https://meta.stackexchange.com/help/l...
The original Question post is licensed under the 'CC BY-SA 4.0' ( https://creativecommons.org/licenses/... ) license, and the original Answer post is licensed under the 'CC BY-SA 4.0' ( https://creativecommons.org/licenses/... ) license.

If anything seems off to you, please feel free to write me at vlogize [AT] gmail [DOT] com.
---
How to Start a Docker Container in User Mode with Read-Write Access

When working with Docker, especially while using images like Ubuntu, you may encounter permission issues that hinder your ability to create files and directories. This guide addresses a common problem faced by developers: starting a Docker container in user mode while ensuring that the user has the necessary permissions to modify files and folders.

The Problem: Permission Denied for Non-Root Users

In the scenario presented, a user tries to log into a Docker container as a non-root user, only to find that they are unable to create new files or folders. Here's a brief overview of the steps they took:

Pulled the Docker image: docker pull ubuntu:18.04

Created a new container: docker run -ti -v $(pwd):/home/shared --name ubuntu_test ubuntu:18.04

Started the container: docker start ubuntu_test

Logged in as root user, updated OS, and installed Vim:

docker exec -ti ubuntu_test /bin/bash

Executed apt update and apt install -y vim

Tried logging in as a non-root user: docker exec -ti -u daemon ubuntu_test /bin/bash

Encountered permission issues: Unable to create files or folders.

The underlying issue is that by default, Docker containers operate with root permissions, and files created within the container are owned by the root user. When switching to a non-root user, the permissions may restrict access to modify those files unless explicitly configured.

The Solution: Creating a User with Permissions

Step 1: Create a New User in the Dockerfile

You can create a new user along with a home directory right when you build your Docker image. This user will have ownership over its home directory, allowing for read-write access.

Here's an example of a Dockerfile that creates a new user:

[[See Video to Reveal this Text or Code Snippet]]

Step 2: Build the Docker Image

To test this Dockerfile, build your Docker image with the following command:

[[See Video to Reveal this Text or Code Snippet]]

Step 3: Run the Container as the New User

You can now run the container and log in as the newly created user:

[[See Video to Reveal this Text or Code Snippet]]

Once inside the container, navigate to the user’s home directory:

[[See Video to Reveal this Text or Code Snippet]]

Try to create a new file:

[[See Video to Reveal this Text or Code Snippet]]

This should succeed, indicating that the new user has read-write access in its home directory.

Step 4: Managing Ownership of Additional Folders

If you require your user to have control over additional folders outside of their home directory, you can change the ownership of those folders using the chown command. This command makes the specified user the owner of a folder and all its contents.

For example, to change ownership of the /etc folder, modify your Dockerfile as follows:

[[See Video to Reveal this Text or Code Snippet]]

Conclusion

By following these steps, you can successfully start a Docker container in user mode with read-write access. This setup not only allows the non-root user to create files and folders but also adheres to good security practices by limiting root access where unnecessary.

Implementing a user management strategy is crucial when working with Docker containers, especially in shared environments. With this guide, you are now equipped to handle user permissions within your Docker containers effectively.