How to enter the previous docker

With the popularity and widespread use of Docker, many developers will use this containerization technology in application deployment and maintenance. But some people may have had issues getting into previous Docker containers. So how to enter the previous Docker?

In this article, we will introduce you how to enter the previous Docker container. We will introduce two methods respectively: using the Docker attach command and using the nsenter tool.

Part 1: Using the Docker attach command

The Docker attach command is a way to enter the container using the Docker command line tool. It allows you to run commands in interactive mode inside the container, just like in the console. The following are the steps to use the Docker attach command to enter the container:

Step 1: Understand the container ID or name

Before using the Docker attach command, we need to know the ID or name of the Docker container to enter . You can use the following command to get the container ID or name:

docker ps -a

This command will display a list of all Docker containers, including their names, IDs, status and other information. Find the container you want to enter and copy its ID or name.

Step 2: Run the Docker attach command

Use the following command to enter a running Docker container:

docker attach container-id

Here, container-id It is the container ID or name obtained in the previous step. After running this command, you will be inside the container and can run interactive commands within it.

Please note that the Docker attach command may not work with all types of containers. If the container is running in the background, you will not be able to enter it using this command.

Part 2: Using the nsenter tool

If you want to run commands in a Docker container that you exited before, you can use the nsenter tool. nsenter is a tool for Linux systems that allows you to enter an isolated namespace. The following are the steps to use the nsenter tool to enter the container:

Step 1: Install the nsenter tool

Before using the nsenter tool, we need to install it first. You can use the following curl command to install the nsenter tool:

curl -o /tmp/nsenter https://raw.githubusercontent.com/jpetazzo/nsenter/master/nsenter && chmod +x /tmp/nsenter

This command will download the nsenter script from GitHub, save it to the /tmp/nsenter file, and add it to the system environment variables.

Step 2: Run the nsenter command

Use the following command to enter the Docker container that you exited before:

docker inspect --format '{{.State.Pid}}' container-id > /tmp/container-pid
sudo /tmp/nsenter --target $(cat /tmp/container-pid) --mount --uts --ipc --net --pid

Here, container-id is you The container ID or name to enter. After running this command, you will be inside the container and can run commands within it.

Please note that the nsenter tool needs to be run with superuser root privileges.

Summary

In this article, we introduced two different methods to enter the previous Docker container. You can choose to use the Docker attach command to directly enter a running container, or use the nsenter tool to enter a stopped container. No matter which method you choose, using Docker containers will become easier, and application deployment and maintenance will be more convenient.

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