How to use Docker containers to run without exiting

Docker is an open source containerization platform that provides an environment that allows developers to package applications and all their dependencies into a portable container for deployment and management. The advantages of Docker containers are that they are fast, lightweight, have strong isolation and portability. However, in actual applications, we often need a feature that does not exit the Docker container immediately after running to ensure that our services run normally and stably.

In this article, we will introduce how to use Docker containers to run without exiting.

1. Use the Bash method to implement the container without exiting

Use the Bash method to implement the Docker container without exiting. You need to run the following command:

docker run -it --name=容器名称 --restart=always 镜像名称 /bin/bash

In this command, we specify The startup mode of the Docker container is an interactive terminal with the name container name, and container name is set to the default startup name after restart, which ensures that the container will not exit abnormally. Unable to restore itself. And --restart=always is used to specify that when the Docker container crashes or stops, the container should be restarted, and Docker will automatically restart the container. The final Image name refers to what image should be used to start the container.

2. Use Python scripts to prevent the container from exiting

In addition to using Bash, we can also use Python scripts to prevent the Docker container from exiting. Below is the Python script:

import time
while True:
    time.sleep(60)

We save this code as a run.py file and add the following line in the Dockerfile:

CMD python /app/run.py

Next, we use docker buildThe command builds the Dockerfile as an image, and then uses the following command to run the container:

docker run -d --restart=always 镜像名称

In this command, we specify that the Docker container will be started in background mode, and the image name is the previously built one. Mirror. --restart=always is also used to specify that when a Docker container crashes or stops, the container should be restarted.

3. Use Supervisor to prevent the container from exiting

Supervisor is a process manager that can be used to monitor and control processes running within Docker containers. Supervisor allows you to perform health checks on processes within containers and ensure that they stay running, automatically restarting even if the process crashes.

1. First, we need to add the following lines to the Dockerfile to ensure that the Supervisor runs properly when the container starts:

RUN apt-get update && apt-get install -y supervisor
RUN systemctl enable supervisor
ADD supervisor.conf /etc/supervisor/conf.d/

2. Next, we need to define the supervisor .conf configuration file that defines which processes should be monitored and how to run them. The following is a simple version of the supervisor.conf file:

[supervisord]
nodaemon=true

[program:your_application_name]
command=/bin/bash -c "while true; do echo hello world; sleep 10; done"

In this configuration file, we define a program named your_application_name and specify It is executed with the /bin/bash command and runs the echo hello world; sleep 10; command in an infinite loop.

3. Finally, when the container starts, you need to use the following command to start the Supervisor:

/usr/bin/supervisord -n -c /etc/supervisor/supervisord.conf

In this command, we pass the -n parameter, Set the Supervisor process to run in the foreground. At startup, Supervisor will detect all configuration files in the /etc/supervisor/conf.d/ directory and use them to manage processes in the container.

Conclusion

In this article, we have given three methods to realize the feature of running Docker containers without exiting, including using Bash method, Python script and Supervisor process manager. Each method has its advantages and scope of application. In practical applications, the appropriate method needs to be selected based on the specific situation. We hope this article is helpful to you and provides better guarantee for the operation of your Docker container.

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