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Adds title, description, type, domain, and tags frontmatter to every doc for improved KB semantic search. The description field is prepended to every search chunk, and domain/type/tags enable filtered queries. Type values: context, guide, runbook, reference, troubleshooting Domain values match directory structure (networking, docker, etc.) Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
95 lines
2.1 KiB
Markdown
95 lines
2.1 KiB
Markdown
---
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title: "Docker Quick Troubleshooting Reference"
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description: "Concise quick-reference for common Docker troubleshooting commands covering container startup, build failures, performance monitoring, network debugging, and system cleanup."
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type: troubleshooting
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domain: docker
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tags: [docker, troubleshooting, quick-reference, networking, builds, cleanup]
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---
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# Docker Troubleshooting Reference
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## Container Won't Start
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### Check logs
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```bash
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docker logs <container_name>
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docker logs --tail 50 -f <container_name>
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```
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### Common issues
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- **Port already in use**: `docker ps` to find conflicting containers
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- **Permission errors**: Check file ownership and container user
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- **Missing environment variables**: Verify with `docker exec -it <container> env`
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- **Resource limits**: Check memory/CPU constraints
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### Debug running container
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```bash
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docker exec -it <container> /bin/bash
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docker exec -it <container> /bin/sh # if bash not available
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```
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## Build Issues
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### Clear build cache
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```bash
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docker system prune -a
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docker builder prune
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```
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### Build with verbose output
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```bash
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docker build --progress=plain --no-cache .
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```
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### Common build failures
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- **COPY/ADD errors**: Check file paths and .dockerignore
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- **Package installation**: Update package lists first
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- **Network issues**: Check DNS and proxy settings
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## Performance Issues
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### Container resource usage
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```bash
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docker stats
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docker exec <container> top
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docker exec <container> free -h
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```
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### Image size optimization
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```bash
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docker images --format "table {{.Repository}}\t{{.Tag}}\t{{.Size}}"
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docker history <image>
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```
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## Network Debugging
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### List networks and connections
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```bash
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docker network ls
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docker network inspect <network_name>
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docker port <container>
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```
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### Test connectivity
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```bash
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docker exec <container> ping <target>
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docker exec <container> nslookup <hostname>
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docker exec <container> netstat -tulpn
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```
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## Quick Fixes
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### Remove all stopped containers
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```bash
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docker container prune
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```
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### Remove unused images
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```bash
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docker image prune -a
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```
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### Reset Docker completely
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```bash
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docker system prune -a --volumes
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``` |