What does daemon process mean in docker

In docker, the daemon process is used to monitor the specified process. When the target process is found to be working abnormally, the target process can be controlled; a daemon process can guard multiple target processes. In the daemon process In , the guardian manages the target process by using the heartbeat mechanism.

The operating environment of this tutorial: linux7.3 system, docker-1.13.1 version, Dell G3 computer.

What is the meaning of daemon process in docker

The daemon process can be understood as process daemon (daemon of the process), which is used to monitor the specified process. When the target process is found to be working abnormally, it can be The target process is controlled. Such as closing the process and restarting the process.

Daemon process (guardian program), target process (daemonized process).

A daemon process can guard multiple target processes

The implementation mechanism of the daemon process:

In the daemon process, the guardian manages the target process by using heartbeats implemented by the mechanism.

The target process will regularly send reports (sending heartbeats) to the guardian, indicating that the target process is running normally and provides corresponding services to the outside world.

When the guardian does not receive the report (heartbeat) sent by the target process for a long time, the guardian will think that the target process is running abnormally, the guardian will shut down the target process, and then restart the target process.

Check whether the docker daemon is running

Root user operation

In Ubuntu system

status docker
stop docker
start docker

In redHat/CentOS system

service docker stop 
service docker start

Recommended learning: "docker video tutorial"

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