red-shadow@blackbox:~/blogs$ cat blog

Docker-Onchange-Exec

Github Repo Link

This Docker repository hosts a versatile Python script (on-change.py) designed for development environment automation. The script enables automated actions based on file modifications, including triggering dev deployment through Docker, avoiding the need for continuous integration and continuous deployment (CI/CD) in a local development setup. It's a valuable tool for streamlined development workflows, enabling auto-execution of specified commands when files change, enhancing efficiency and aiding in various use cases such as:

• Dev environment auto-deployment
• Auto-reloading applications for faster development iterations
• Running test suites upon code changes
• Enabling automated actions for specific file modifications This repository simplifies and enhances the development process by leveraging Docker and automation for seamless local development experiences.

Usage Details

To monitor and continuously perform git pull with the given filepath, detecting changes in the package.json file, and triggering an npm install if changes are detected, you can use the following docker run command:

docker run -ti \
    -v /var/run/docker.sock:/var/run/docker.sock \
    --privileged \
    -e FILES_TO_CHECK=/work-dir/package.json \
    -e COMMAND_TO_CHECK=sh -c "/usr/bin/git config --global --add safe.directory /work-dir && /usr/bin/git pull" \
    -e COMMAND_TO_RUN="/usr/local/bin/npm install" \
    -e CONTAINER_NAME=main-app \
    -e SLEEP_INTERVAL=10 \
    r3dshadow/docker-onchange-exec:1.1

Explanation of Environment Variables

• FILES_TO_CHECK=/work-dir/package.json: Specifies the file to monitor for changes, in this case, package.json.
• COMMAND_TO_CHECK="/usr/bin/git pull": Defines the command to check for changes, set to git pull in this example.
• COMMAND_TO_RUN="/usr/local/bin/npm install": Specifies the command to execute when changes are detected, in this case, npm install.
• CONTAINER_NAME=main-app: Specifies the target container where COMMAND_TO_RUN should be executed, in this example, set to main-app.
• SLEEP_INTERVAL=10: Sets the interval (in seconds) at which the script checks for changes, in this case, set to every 10 seconds.
• --privileged: Provides elevated privileges to the container, allowing it to perform privileged tasks.
• -v /var/run/docker.sock:/var/run/docker.sock: Binds the Docker socket of the host to the Docker socket inside the container, enabling communication with the Docker daemon.

Example

Explore the https://github.com/r3d-shadow/docker-onchange-exec/tree/main/example example folder to understand how you can structure your project and adapt the Docker Compose configuration.

version: '2.17'
networks:
  my-network:
    name: my-network
services:
  main-app:
    restart: always
    container_name: main-app
    build:
      context: .
      dockerfile: ./Dockerfile
  git-on-change:
    depends_on:
      - main-app
    restart: unless-stopped
    image: r3dshadow/docker-onchange-exec:1.1
    privileged: true
    environment:
      - FILES_TO_CHECK=/work-dir/package.json
      - COMMAND_TO_CHECK=sh -c "/usr/bin/git config --global --add safe.directory /work-dir && /usr/bin/git pull"
      - COMMAND_TO_RUN=/usr/local/bin/npm install
      - CONTAINER_NAME=main-app
      - SLEEP_INTERVAL=10
    volumes:
      - '/var/run/docker.sock:/var/run/docker.sock'

This configuration sets up two services: main-app and git-on-change. The git-on-change service will monitor the package.json file and automatically run git pull and npm install on main-app container when changes are detected.