--- name: docker-ops description: Docker container lifecycle management, health checks, log analysis, cleanup, compose orchestration, and troubleshooting. Use when Codex needs to manage Docker containers, debug running services, inspect logs, clean up resources, or orchestrate multi-service setups with Docker Compose. --- # Docker Ops ## Overview Docker container lifecycle management, health checks, log analysis, cleanup, compose orchestration, and troubleshooting. Use when Codex needs to manage Docker containers, debug running services, or clean up Docker resources. ## Quick Start ### Prerequisites - Docker Engine (docker CLI) - `docker compose` plugin (for compose) ### Check what's running ```bash docker ps -a --format 'table {{.Names}}\t{{.Status}}\t{{.Ports}}\t{{.Image}}' docker stats --no-stream # live resource usage ``` ### Inspect a container ```bash docker inspect | jq '.[0].State' # status, exit code, health docker inspect --format '{{json .Mounts}}' | jq . ``` ### Logs analysis ```bash docker logs --tail 100 --since 5m # Use docker-log-inspector.py for filtering: python3 scripts/docker-log-inspector.py --since 30m --filter ERROR --summary ``` ### Clean up unused resources ```bash # Standard cleanup bash scripts/docker-cleanup.sh # Aggressive cleanup (removes volumes + build cache) bash scripts/docker-cleanup.sh --aggressive # Preview only bash scripts/docker-cleanup.sh --dry-run ``` ### Health check ```bash bash scripts/docker-health.sh # all containers bash scripts/docker-health.sh # single container ``` ## Common Tasks ### Docker Compose workflows ```bash docker compose up -d # start services docker compose down -v # stop + remove volumes docker compose logs -f --tail 50 # follow logs docker compose ps # status docker compose exec sh # shell into a service docker compose build --no-cache # rebuild without cache docker compose restart # restart one service ``` ### Port conflicts ```bash # Find what's using a port sudo lsof -i : docker ps --format '{{.Names}} {{.Ports}}' | grep # Fix: change port mapping in docker-compose.yml or stop conflicting container ``` ### Resource limits and OOM ```bash docker inspect --format '{{json .HostConfig.Memory}}' docker stats --no-stream # Fix: add to docker-compose.yml # deploy: # resources: # limits: # memory: 512M # cpus: '0.5' ``` ### Image management ```bash docker images --format 'table {{.Repository}}\t{{.Tag}}\t{{.Size}}\t{{.CreatedSince}}' docker image prune -a # remove all unused images docker rmi # remove specific image docker pull : # update image docker build -t : . # build docker build --no-cache -t . # force rebuild ``` ### Network troubleshooting ```bash docker network ls docker network inspect # Test connectivity from a container: docker exec ping docker exec curl -v http://service:port ``` ### Data volumes ```bash docker volume ls docker volume inspect docker run --rm -v :/data alpine ls -la /data # inspect volume contents ``` ## Troubleshooting ### Container exits immediately ```bash docker logs # check exit reason docker inspect --format '{{.State.ExitCode}}' # Common causes: # 0 → clean exit (expected?) # 1 → application error (check logs) # 137 → SIGKILL (OOM kill) # 139 → segfault ``` ### Disk space issues ```bash docker system df # disk overview du -sh /var/lib/docker/containers/ # container overlay sizes bash scripts/docker-cleanup.sh --aggressive ``` ### Container can't resolve DNS ```bash docker exec cat /etc/resolv.conf # Fix: add to docker-compose.yml # dns: # - 8.8.8.8 # - 1.1.1.1 ``` ### Permission errors ```bash # Add user to docker group sudo usermod -aG docker $USER && newgrp docker ``` ## Resources - **`scripts/docker-cleanup.sh`** — Interactive cleanup with dry-run mode - **`scripts/docker-health.sh`** — Multi-container health overview - **`scripts/docker-log-inspector.py`** — Regex filtering + severity summary for logs - **`references/compose-patterns.md`** — Docker Compose patterns and recipes

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