On the host, containers are running, one has stopped responding. How will you check what is happening with it?

To diagnose a container that has stopped responding, I would take the following steps:

1. Check the container status with the command docker ps -a or docker container ls -a to see if it is running, stopped, or in an error state.

2. View the container logs using docker logs <container_id> to understand if there are any errors or exceptions within the application.

3. If the container is running but not responding, I would connect inside using docker exec -it <container_id> /bin/sh or /bin/bash and check the application's status, processes, and network connections.

4. Check the host resources (CPU, memory, disk) using top, htop, df -h to rule out resource shortages.

5. If the container uses network ports, verify whether the application is listening on the required port (netstat -tulnp or ss -tulnp).

6. If necessary, restart the container with docker restart <container_id> and observe its behavior.

7. If the container is managed by an orchestrator (e.g., Kubernetes), check the Pod status and events with kubectl describe pod <pod_name> and view logs with kubectl logs <pod_name>.

This approach allows for quick localization of the problem and understanding why the container stopped responding.