Docker commands

Here’s a concise summary of basic Docker commands:

1. docker --version: Check Docker version.
2. docker pull <image>: Download an image from Docker Hub.
3. docker images: List locally available Docker images.
4. docker run -d -p <host_port>:<container_port> <image>: Run a container in detached mode and map ports.
5. docker ps: List running containers.
6. docker stop <container_id>: Stop a running container.
7. docker rm <container_id>: Remove a stopped container.
8. docker rmi <image>: Remove a Docker image.
9. docker exec -it <container_id> /bin/bash: Run a command inside a container.
10. docker logs <container_id>: View container logs.
11. docker build -t <tag> .: Build an image from a Dockerfile.
12. docker inspect <container_id>: Get detailed info about a container or image.
13. docker-compose up: Start services as defined in docker-compose.yml.
14. docker-compose down: Stop and remove services, networks, and volumes.

These commands cover the essential aspects of Docker usage.
Here are the steps with sample Docker commands:

1. Develop: Write your application code (e.g., a Python or Node.js application).

2. Dockerfile: Create a file named Dockerfile in the root of your project directory. Example Dockerfile for a Python Flask app:
   

   # Use an official Python runtime as a parent image
   FROM python:3.9-slim

   # Set the working directory
   WORKDIR /app

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

   # Install any needed packages specified in requirements.txt
   RUN pip install --no-cache-dir -r requirements.txt

   # Make port 80 available to the world outside this container
   EXPOSE 80

   # Define environment variable
   ENV NAME World

   # Run app.py when the container launches
   CMD ["python", "app.py"]

1. Build Image: Run this command in your terminal to build your Docker image:

   docker build -t my-app .

Here, -t my-app tags the image as my-app.

1. Run Container: Use the following command to start a container from the image:

   docker run -d -p 5000:80 my-app

The -d flag runs the container in the background, and -p 5000:80 maps port 5000 on your machine to port 80 on the container.

1. Test: After running the container, test the app by opening http://localhost:5000 in your browser. If you make changes to your code:

   • Rebuild the image:

    docker build -t my-app .
   

• Stop the old container:
  

   docker stop <container_id>
  

• Remove the container:
  

   docker rm <container_id>
  

• Run a new container with the updated image:
  

   docker run -d -p 5000:80 my-app
  

1. Push (Optional): To share your Docker image on Docker Hub, first log in to Docker Hub:

   docker login

Then push your image:

   docker tag my-app your_dockerhub_username/my-app
   docker push your_dockerhub_username/my-app

1. Pull (Optional): Others can pull your image from Docker Hub and run it using:

   docker pull your_dockerhub_username/my-app
   docker run -d -p 5000:80 your_dockerhub_username/my-app

These commands will help you get started with containerizing and sharing your application using Docker. Let me know if you need further assistance!