Docker Troubleshooting Guide: Common Issues and Solutions

This guide covers numerous Docker-related problems and their solutions, offering step‑by‑step instructions and code snippets for each scenario.

1. Storage migration : Move Docker's data directory from /var/lib/docker to another location using systemctl stop docker, mv, and a symbolic link, or edit the daemon configuration with --graph or daemon.json.

2. Disk space issues : Identify large directories with du, clean logs, adjust docker-compose storage options, or increase the size of the Docker storage pool.

3. Missing shared libraries : Resolve errors like libz.so.1 by ensuring proper permissions on /tmp or reinstalling required packages.

4. Container corruption : Remove corrupted containers by deleting their directories under /var/lib/docker/containers and restarting the Docker service.

5. Network and port problems : Fix 502 errors caused by incorrect localhost references, configure IPv4 bindings, disable IPv6 if unsupported, and adjust firewall rules to allow required ports.

6. Permission errors for non‑root users : Adjust Nginx or other service configurations to use directories with appropriate permissions when running containers as non‑root users.

7. Docker command usage : Explain the difference between -i and -t flags for docker exec and provide guidance for CI pipelines, cron jobs, and scripts.

8. Image management : Show how to identify dependent images, remove dangling images, and correctly reference image tags.

9. Environment variables in Compose : Recommend avoiding quotes around variables in docker-compose.yml to prevent parsing issues.

10. Timeout configuration : Increase COMPOSE_HTTP_TIMEOUT and DOCKER_CLIENT_TIMEOUT to avoid long‑running compose failures.