Docker Troubleshooting & FAQs

Even seasoned developers face Docker hiccups. This page lists common problems, debugging tips, and optimization strategies to help you resolve issues and streamline container workflows.

Common Docker Errors and Fixes

Port already allocated: A container is already using the port.
```
docker ps -a
docker rm -f container_id
```
Cannot connect to Docker daemon: Docker isn't running or permission is denied.
- Start the Docker service
- Add user to Docker group:
```
sudo usermod -aG docker $USER
```
Image pull failed: Check internet connection, Docker Hub login, or proxy/firewall issues.

Debugging Containers

Access container shell:

docker exec -it container_name /bin/bash

View logs:
```
docker logs container_name
```
Inspect container or network:
```
docker inspect container_or_network
```

Performance Optimization Tips

Use Alpine or slim images
Combine RUN instructions to reduce layers
Limit running processes to only what's needed
Prune unused images, containers, volumes:
```
docker system prune -a
```

Helpful Resources

Whether you're debugging a failing container or tuning performance, these tips and tools will keep your Docker workflow productive and efficient.

← Previous: Real-World Docker Use Cases Back to Start ↑