Docker Hello World (with NodeJS)

Based on https://nodejs.org/en/docs/guides/nodejs-docker-webapp

Demo Setup

• docker build -t node-web-app .
• docker run -d --name nwa --restart unless-stopped -e PORT=80 -e CRASHTEST=true -p 8080:80 node-web-app
• goto http://localhost:80
• docker ps, the app will crash after 10 seconds and restart automatically, but also start after reboot.
• If running VS Code get recommended extensions (optional)

Other Repos/Learnings

• https://github.com/picode7/minecraft-docker-hetzner
• https://github.com/picode7/deno-docker

General Usage

• Optional: For local development npm install
• Build image docker build -t node-web-app .
  • -t stands for --tag more
• List image docker images
• Run image docker run -d --name nwa -p 8080:8080 node-web-app, name is optional, but can be used as ID without having to look it up later. It can only be used once
  • add -e PORT=8081 or --env to overwrite the PORT environment variable from the dockerfile
  • -d stands for --detach and runs the container in the background
  • -p stands for --publish to publish the containers ports
  • --restart unless-stopped to restart the container on reboot or failure etc., but not manual stop. more
• docker update <flags> <container id> to update settings
• Get outputs
  • Get container id docker ps
  • Print outputs docker logs <container id>
• Exec inside container docker exec -it <container id> /bin/bash, return with exit
• Server exposed outside container at http://localhost:8080
• Stop container docker stop <container id>
• Start container docker start <container id>
• Remove container docker rm <container id>
• Stop, remove, rebuild and rerun to update changes
• Remove all containers, images and cache docker system prune -a, confirm with y

Docker Caching and Layers

• For ADD or COPY docker auto-detects if there has been file changes since the last cached build. If yes it will rebuild from there on, otherwise skip until the next possible change and check again.
• For example npm install is not needed to run again, if the package*.json files didn't change. So putting COPY package*.json ./ infront, instead of all the files (COPY . .) will allow docker to detect, that nothing relevant for npm install changed, even if the source code did.
• If possible it thus makes sense to put the least likely to change commands first
• more here

Volumes

• Create docker volume create <volume-name>
• Run docker run -v <volume-name>:<folder in image to equal volume> <image>
• Remove docker volume rm <volume-name>
• List volumes docker volume ls
• Inspect volume docker volume inspect <volume-name>
• Disk location when using Windows+WSL for volumes pointing to /var/lib/docker/: \\wsl$\docker-desktop-data\version-pack-data\community\docker\volumes\ (open in Windows-Explorer)
• Backup volumes https://docs.docker.com/storage/volumes/#backup-restore-or-migrate-data-volumes

Docker Compose

• Create a docker-compose.yml and create the config you need
• Start docker compose up -d - -d for detached like in docker run
• Stop and remove docker compose down, to also remove volumes add --volumes

Publishing Image

• Using GitHub Container Registry, publishing manually:
  • Following https://docs.github.com/en/packages/guides/pushing-and-pulling-docker-images (beta)
  • Create access token and login echo $CR_PAT | docker login ghcr.io -u USERNAME --password-stdin
  • Build docker build -t ghcr.io/<githubname>/<packagename> .
  • Push latest version docker push ghcr.io/OWNER/IMAGE_NAME:latest .
  • Push another version docker push ghcr.io/OWNER/IMAGE_NAME:1.1 ., you might to want to push the new version also to the latest tag
  • docker run ghcr.io/OWNER/IMAGE_NAME or to only download docker pull ghcr.io/OWNER/IMAGE_NAME:latest
  • Image size (not clear if it matches the size you might pay for on GitHub private docker manifest inspect -v ghcr.io/OWNER/IMAGE_NAME | grep size | awk -F ':' '{sum+=$NF} END {print sum}' | numfmt --to=iec-i source (sums up the manifest you can also see on GitHub)

GitHub Workflow for GitHub Container Registry

• See .github/workflows/deploy.yml
• Reference the GitHub Repo, add this to the Dockerfile: LABEL org.opencontainers.image.source https://github.com/OWNER/REPO or --label "org.opencontainers.image.source=https://github.com/OWNER/REPO" in the docker build command. This will also show the package in the repositories "packages" list.
• Making the package public has do be done manually (private by default, also for public repos).