How to solve the problem of setting docker to start automatically

When using Docker, sometimes we need to set Docker to start automatically so that Docker will also start when the system starts. But in some cases, Docker will fail to start automatically. Next, this article will introduce how to solve the problem of Docker automatic startup failure.

1. Check Docker status

First we need to check the startup status of Docker, use the following command:

$ sudo systemctl status docker

If the Docker service is already running:

docker.service - Docker Application Container Engine
   Loaded: loaded (/lib/systemd/system/docker.service; disabled; vendor preset: enabled)
   Active: active (running) since Wed 2021-06-23 16:23:15 CST; 7min ago
     Docs: https://docs.docker.com
 Main PID: 2915 (dockerd)
  Tasks: 20
...

If Docker is not running:

docker.service - Docker Application Container Engine
   Loaded: loaded (/lib/systemd/system/docker.service; disabled; vendor preset: enabled)
   Active: inactive (dead)
     Docs: https://docs.docker.com

If Docker is not running, please use the following command to start the Docker service:

$ sudo systemctl start docker

2. View Docker auto-start status

Then we need to check the self-starting status of Docker, use the following command:

$ sudo systemctl is-enabled docker

If the output result is enabled, it means that Docker has been set to self-starting; if the output result is disabled, you need to set Docker to start automatically, use the following command:

$ sudo systemctl enable docker

3. View the Docker startup log

If the previous steps do not solve the problem of Docker self-starting For startup failures, we can check the Docker startup log to find out the cause of the failure. Use the following command to view the Docker startup log:

$ sudo journalctl -u docker.service

By viewing the log, you can find specific error messages. Some common error messages are:

• Failed to start Docker Application Container Engine.: Docker failed to start. It may be that the systemd controller cannot communicate with Docker, or the Docker child process failed to start, etc. The problem needs to be further investigated.
• Error starting daemon: error initializing graphdriver: ...: Docker startup failed, possibly because writability is disabled, insufficient disk space, incompatible driver version, etc.
• time="2021-06-23T16:23:14Z" level=fatal msg="Your Linux kernel version 3.2.0-112-generic is not supported for running docker. Please upgrade your kernel to 3.10.0 or newer.": Docker failed to start, possibly because the Linux kernel version is too low and needs to be upgraded to 3.10.0 or higher.

After troubleshooting the problem based on the error message, try restarting the Docker service until successful.

Summary

This article introduces the problem of Docker automatic startup failure and its solution. In general, by checking the Docker status, setting Docker to start automatically, and viewing the Docker startup log, we can eliminate most fault causes and ensure that Docker starts normally. Of course, if none of the above methods can solve the Docker auto-start failure, it is recommended to check the official Docker documentation or seek help from the community.

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