Containers have become an essential part of modern application development, allowing developers to create and deploy applications quickly and easily. However, managing container images can be challenging, especially when deploying applications to production environments. This is where container registries come in handy. A container registry is a storage system for managing and distributing container images.
DigitalOcean, a popular cloud provider, offers a container registry that provides a secure and scalable way to store and manage your Docker images. In this article, we’ll go over the steps to build a Docker container image and push it to the DigitalOcean container registry.
Prerequisites
Before we get started, you’ll need to have the following:
- A DigitalOcean account
- Docker installed on your machine
doctlcommand-line tool installed and configured with your DigitalOcean account API token.
Step 1: Create a Dockerfile
The first step to building a container image is to create a Dockerfile. A Dockerfile is a text file that contains instructions for building a Docker image. Here’s an example Dockerfile for a simple Python Flask application:
# Use the official Python image as a parent image
FROM python:3.9-slim-buster
# Set the working directory to /app
WORKDIR /app
# Copy the current directory contents into the container at /app
COPY . /app
# Install the required packages
RUN pip install --no-cache-dir -r requirements.txt
# Expose port 5000 for the Flask app
EXPOSE 5000
# Set the command to start the Flask app
CMD ["python", "app.py"]In this example, we’re using the official Python 3.9 image as our base image. We set the working directory to /app, copy the application code to the container, install the required packages, and set the command to start the Flask app. You can customize this Dockerfile to fit your application’s needs.
Step 2: Build the Docker Image
Once you have created the Dockerfile, you can build the Docker image using the Docker build command. In your terminal, navigate to the directory where the Dockerfile is located, and run the following command:
docker build -t your-image-name .If you need to build for a different architecture you should use buildx, like so
docker buildx build –platform linux/amd64 -t your-image-name .
This will build the image with x86 arch on a MAC M1 ex.
Edited
This command tells Docker to build an image with the tag your-image-name using the Dockerfile in the current directory.
Step 3: Log in to the DigitalOcean Container Registry
Before we can push our Docker image to the DigitalOcean container registry, we need to log in to the registry using the doctl command-line tool. In your terminal, run the following command:
doctl registry loginThis command will prompt you for your DigitalOcean account API token, which you can generate from the DigitalOcean control panel. Once you have entered your token, you’ll be logged in to the DigitalOcean container registry.
Step 4: Tag the Docker Image
Now that we’re logged in to the DigitalOcean container registry, we need to tag our Docker image with the registry’s address. In your terminal, run the following command:
docker tag your-image-name registry.digitalocean.com/your-registry-name/your-image-name:latest
Replace your-registry-name with the name of your DigitalOcean container registry. The latest tag is the default tag for Docker images.
Step 5: Push the Docker Image
Finally, we can push our Docker image to the DigitalOcean container registry. In your terminal, run the following command:
docker push registry.digitalocean.com/your-registry-name/your-image-name:latestThis command uploads your Docker image to the DigitalOcean container registry.
Thank you for reading, and happy containerizing!
