Solution to the problem that the docker container cannot be started

Docker is a popular containerization platform that is widely used for development and deployment. However, sometimes you may encounter startup failures when using Docker containers. This article will explore some common problems and provide solutions.

1. Check container status

First, we need to check the status of the container. Use the command docker ps -a to view the status of all containers, including running and non-running containers. If the container status is Exited, it means that the container has stopped running.

$ docker ps -a
CONTAINER ID        IMAGE               COMMAND             CREATED             STATUS                        PORTS               NAMES
8a9506b91d24        nginx               "nginx -g 'daemon of…"   2 hours ago         Exited (1) 2 hours ago                            nginx-container

2. Check the container log

When the container fails to start, we can get more detailed information by checking the container log. Use the command docker logs CONTAINER_NAME/ID to view the log output of the container. If the container has been shut down at this time, you can use the parameter -f to continue viewing the log.

$ docker logs nginx-container
2021/08/23 08:08:09 [emerg] 1#1: bind() to 0.0.0.0:80 failed (98: Address already in use)
...

Taking the above nginx-container as an example, you can see that the error message is bind() to 0.0.0.0:80 failed (98: Address already in use), indicating that port 80 is already occupied, so the container cannot be started.

3. Check container port mapping

The previous error message has mentioned the port occupation problem, so we need to check whether the port mapping of the container is correct. Use the command docker port CONTAINER_NAME/ID to view the port mapping of the container.

$ docker port nginx-container
80/tcp -> 0.0.0.0:8080

The above output shows that port 80 of the container is mapped to port 8080 of the host, so we need to check whether port 8080 of the host is occupied.

4. Check the internal services of the container

Sometimes the container startup fails because the internal services cannot start normally. For example, database container connection failure, configuration issues with the application itself, etc. In this case, we need to go inside the container, run the service manually and check the output.

Use the command docker exec -it CONTAINER_NAME/ID bash to enter the container.

$ docker exec -it nginx-container bash

Inside the container, run the service that needs to be checked and view the output information.

5. Rebuild the image

If the container cannot be started and none of the above methods help, you can try to rebuild the container. First, we need to stop and delete the original container.

$ docker stop nginx-container
$ docker rm nginx-container

Then, rebuild the image and run the container.

$ docker build -t my-nginx .
$ docker run -d --name nginx-container -p 8080:80 my-nginx

The above are some common reasons and solutions that cause Docker containers to fail to start. Of course, there are other more complex reasons. There are also many details and configuration options that need to be paid attention to when using Docker containers. I hope readers can master the basic skills of container development.

The above is the detailed content of Solution to the problem that the docker container cannot be started. For more information, please follow other related articles on the PHP Chinese website!