Containers

Containers

Init #

  • docker run hello-world - run container from hello world image

Samples #

Application # 

cat > app.js <<EOF
const http = require('http');

const hostname = '0.0.0.0';
const port = 80;

const server = http.createServer((req, res) => {
    res.statusCode = 200;
      res.setHeader('Content-Type', 'text/plain');
        res.end('Hello World\n');
});

server.listen(port, hostname, () => {
    console.log('Server running at http://%s:%s/', hostname, port);
});

process.on('SIGINT', function() {
    console.log('Caught interrupt signal and will exit');
    process.exit();
});
EOF

Dockerfile # 

cat > Dockerfile <<EOF
# Use an official Node runtime as the parent image
FROM node:6

# Set the working directory in the container to /app
WORKDIR /app

# Copy the current directory contents into the container at /app
ADD . /app

# Make the container's port 80 available to the outside world
EXPOSE 80

# Run app.js using node when the container launches
CMD ["node", "app.js"]
EOF

Build #

  • docker images - list all downloaded images
  • docker build -t node-app:0.1 . - build image from sources with with tag node-app:0.1
  • docker rm my-app - remove image

Run #

  • docker ps - list all running containers
  • docker ps -a - list all containers including all which are stopped
  • docker run -p 4000:80 --name my-app node-app:0.1 - running container in attached mode
  • docker run -p 4000:80 --name my-app -d node-app:0.1 - running container in detached mode (in background)
  • docker stop my-app - stop container

Debug #

  • docker logs <container-id> - displays logs
  • docker logs -f <container-id> - displays logs with follow
  • docker exec -it <container-id> /bin/bash - “enter” container (ssh replacement)
  • docker inspect <container-id>
  • docker ps --format='{{.ID}}\t{{.Label "pl.xperios.project"}}' - outputs all running container and label with key pl.xperios.project

Publish #

  • docker tag node-app:0.2 gcr.io/[project-id]/node-app:0.2 - create new image with new tag from existing one
  • gcloud docker -- push gcr.io/[project-id]/node-app:0.2 - push image to the gcr repository

To push images to your private registry hosted by gcr, you need to tag the images with a registry name. The format is [hostname]/[project-id]/[image]:[tag]. For gcr:

  • [hostname] is gcr.io
  • [project-id] is your project’s ID
  • [image] is your image name
  • [tag] is any string tag of your choice. If unspecified, it defaults to “latest”.

Clean up #

  • docker system df - docker disk usage
  • docker stop $(docker ps -a -q) - stop all containers
  • docker rm $(docker ps -a -q) - delete all containers
  • docker rmi $(docker images -q) - delete all images

Podman #

  1. Run cmd.exe as administrator.
  2. Create symlink: mklink "C:\Program Files\RedHat\Podman\docker.exe" "C:\Program Files\RedHat\Podman\podman.exe"
  3. Test: docker version

Recipes #

Build with maven #

  • docker run --rm -v "$(pwd)":/app -w /app maven mvn clean install - simple run
  • docker run --rm -v "$(pwd)":/app -v maven-repo:/root/.m2 -w /app maven mvn clean install - preserve local repo

Nodejs #

  • docker run -it --rm --name my-running-script -v "$PWD":/usr/src/app -w /usr/src/app node:8 node your-daemon-or-script.js - run single script
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