Docker Environment Check

Validate Docker environment health before starting or debugging containerized services.

Steps

1. Check Docker daemon:
   • docker info > /dev/null 2>&1 — is Docker running?
   • If not running, report and suggest starting it
   • Check Docker version: docker --version
2. List running containers:
   • docker ps --format "table \t\t"
   • Flag any containers in unhealthy or restarting state
   • Flag any containers using ports needed by the current project
3. Check port conflicts:
   • Extract ports from docker-compose.yml or Dockerfile
   • Check if those ports are already in use: lsof -i :<port>
   • Report which process is using conflicting ports
4. Validate Docker Compose (if applicable):
   • docker compose config --quiet — is the compose file valid?
   • Check that all referenced images exist or can be built
   • Check that all referenced volumes and networks are defined
   • Verify environment variables and .env file presence
5. Check resource usage:
   • docker system df — disk usage by images, containers, volumes
   • Flag if disk usage is above 80%
   • Suggest docker system prune if significant space can be reclaimed
6. Check image freshness:
   • List local images relevant to the project
   • Flag images older than 30 days that might be stale
   • Check if base images have security updates available
7. Report summary:
   • Docker status: running/stopped
   • Containers: X running, Y stopped, Z unhealthy
   • Port conflicts: list or “none”
   • Disk usage: X GB used
   • Recommendations: actions to take before starting services

Important

• Don’t start or stop containers automatically — report findings and let the user decide.
• Don’t expose secrets from container environment variables in the report.
• Check compose file format — v2 vs v3 syntax differences can cause subtle issues.