Getting Started with Docker: Your First Container
Installing Docker
Before you can run your first container, you need to install Docker on your machine. Docker is available for Windows, macOS, and various Linux distributions. Here's how you can install Docker:
For Windows and macOS:
- Download Docker Desktop from the official Docker website[4].
- Run the installer and follow the on-screen instructions.
- Once installed, launch Docker Desktop.
- Docker will guide you through a tutorial which is optional but recommended for beginners.
For Linux:
- Go to the Docker documentation website and choose your Linux distribution.
- Follow the step-by-step instructions provided for your specific distribution.
- Ensure that your user is added to the
dockergroup so you can execute Docker commands without usingsudo.
Running Your First Container
With Docker installed, you can now run your first container. Docker containers are instances of Docker images, which are templates that include the application code, libraries, dependencies, and other files necessary to run the application.
Step 1: Download a Docker Image
Docker images are available on Docker Hub, which is a repository for Docker images. You can download a simple image like hello-world to test your Docker installation:
docker pull hello-worldThis command fetches the hello-world image from Docker Hub and saves it on your machine.
Step 2: Run the Container
To run a container using the hello-world image, execute:
docker run hello-worldThis command will start a container from the hello-world image. If the image is not found locally, Docker will automatically pull it from Docker Hub. The hello-world container will run, print a message to the console, and then exit.
Step 3: Verify the Container Ran
You can verify that your container ran successfully by listing all the containers, including the stopped ones:
docker ps -aYou should see the hello-world container listed with a status of Exited.
Understanding Docker Commands
Here are some basic Docker commands that you should be familiar with:
docker pull: Downloads an image from Docker Hub.docker run: Creates and starts a container from an image.docker ps: Lists running containers.docker ps -a: Lists all containers, including stopped ones.docker stop: Stops a running container.docker rm: Removes a container.docker images: Lists all images on the local machine.docker rmi: Removes an image.
Building and Running a Simple Application
Now that you've run a pre-made image, let's build and run a simple application:
- Create a directory for your project and navigate into it.
- Create a file named
Dockerfilewithout any extension. - Open the
Dockerfilein a text editor and add the following content:
# Use an official Python runtime as a parent image
FROM python:3.8-slim
# Set the working directory in the container
WORKDIR /usr/src/app
# Copy the current directory contents into the container at /usr/src/app
COPY . .
# 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"]- Create a
requirements.txtfile and list any Python dependencies. - Create an
app.pyfile with a simple web server or script. - Build your Docker image:
docker build -t my-python-app .- Run your application in a new container:
docker run -p 4000:80 my-python-appThis command maps port 4000 on your local machine to port 80 on the container, allowing you to access the application.
Congratulations! You've just containerized and run your first application using Docker. As you continue to explore Docker, you'll discover more advanced features and techniques that can help streamline your development workflow.
Cricket Score Counter
Heads or Tails
You have not logged in, please Login to comment.