Troubleshooting Docker

How would you troubleshoot a container if it is not running? #

Missing or Incorrect Environment Variables: Container fails due to missing or incorrect environment variables
Incorrect Container Command or Entrypoint: Container exits immediately after starting or fails to perform expected tasks
Volume Issues: Container startup fails due to volume mount errors or permissions
Inspect Container Logs: To inspect logs for the container to understand why it might have failed to start
```
docker logs [container_id]
```
Inspect Container Configuration: Retrieve details on container settings, environment variables, volumes, and networking
```
docker inspect [container_id]
```
Review Container Events: Monitor real-time events for errors or warnings during container startup
```
docker events -f [container_id] --since 2m
```
Verify Resource Availability: Ensure adequate CPU, memory, and disk space for container operation
```
docker stats [container_id]
```
Check Docker Engine Logs: Review Docker engine logs for system-level issues that may affect container startup
```
journalctl -u docker.service
```

How do you get all the system-level information about docker? Like events, disk space, caching, etc.. #

Display system-wide information about Docker installation, including number of containers, images, and storage driver details
```
docker info
```
Show Docker disk usage, including total and used space for images, containers, and volumes
```
docker system df
```
Monitor Docker events in real-time, such as container starts/stops, image pulls, and network changes
```
docker events
```
Display real-time CPU, memory, and network usage statistics for running containers
```
docker stats [container_id]
```
Show the history of an image, including commands and metadata used to create each layer
```
docker history [image_name]
```
Return low-level information about Docker objects, such as containers, images, networks, and volumes
```
docker inspect [object_name]
```
Remove unused data, such as stopped containers, dangling images, and unused networks and volumes
```
docker system prune
```
Remove unused images
```
docker image prune
```
Remove unused containers
```
docker container prune
```
Remove unused networks
```
docker network prune
```
Get real-time events from the Docker daemon, similar to docker events
```
docker system events
```