In this tutorial I will tell you what are the possible states of docker containers. Here I am going to tell you about all possible states of docker container.
State generally refers to any changeable conditions including the results of internal operations, interactions with other applications.
States of Docker Container
Created: If your docker container is newly created (docker create), you will see this state for your docker container. In this state, the container is not yet started.
Restarting: A container that is in the process of being restarted. So when you restart your docker container or container restarts itself due to a problem, you will see this state.
Docker has four different restart policies:
- The default is called no. With this policy, the Docker daemon will never try to restart your container (unless you tell it to manually).
- The second policy is on-failure. With this policy, the Docker daemon will try to restart container if any problem exists, that is, if any startup script returns a non-zero exit code.
- The third policy is always. With this policy, the Docker daemon will try restart container if:
- If there is any problem
- If you stop them manually
- The docker daemon was itself stopped and restarted
- The fourth policy is unless-stopped, where the Docker daemon will always try to restart container unless you stop them manually.
Running: A currently running container. Running is the main state you’ll see for container. It means it has started, and there is no problem detected with the container itself.
Paused: A container whose processes have been paused. If you temporarily stop your running Docker container via docker pause, this is what you’ll see until you unpause it.
Exited: A container that ran and completed. If your container has stopped because of a problem or you stopped your container manually, you will see your container in this state, depending on your restart policy as described above.
Dead: A container that the daemon tried and failed to stop (usually due to a busy device or resource used by the container).
How to check Docker Containers
You can verify the running containers using the following command:
$ docker ps
The above command only displays only currently running containers.
If you want to check all containers then you can execute the following command:
$ docker ps -a or $ docker ps -all
The output might be truncated for the above commands, so you can use –no-trunc with the above commands to prevent output truncating. For example, you can use:
$ docker ps --no-trunc
That’s all about possible states of docker containers.