Setting Up a Private Docker Registry Using Nexus

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Prerequisites

• Ubuntu 24.04 server

• Instance type: t2.medium

• Disk: 25GB

• Security Group (SG) open inbound ports: 3000-10000, 80, 443, 22

Step 1: Install Docker

First, update the package index and install Docker.

sudo apt update -y
sudo apt install docker.io -y
sudo usermod -aG docker $USER

To apply the group changes, either log out and log back in, or run:

newgrp docker

Step 2: Setup Nexus Using Docker

Run Nexus in a Docker container.

docker run -d -p 8081:8081 -p 5000:5000 sonatype/nexus3

• Port 5000 will be used for the Docker registry.

• Nexus web interface will run on port 8081.

Step 3: Configure Nexus

1. Allow a few minutes for Nexus to start.

2. Access the Nexus container to retrieve the admin password.

docker exec -it <container_id> /bin/bash
cat sonatype-work/nexus3/admin.password

3. Log in to the Nexus web interface at http://<your-server-ip>:8081 using the retrieved password.

4. Follow the prompts to set a new password.

Create Docker (hosted) Repository

1. Navigate to Settings → Repository → Create Repository → Docker (hosted).

2. Configure the repository as needed.

3. Enable Docker Bearer Token Realm:

   • Go to Security → Realms.

   • Add Docker Bearer Token Realm to the active realms.

   • Save the changes.

Step 4: Configure Docker to Use Insecure Registry

Since the Nexus registry will use HTTP, we need to configure Docker to allow insecure registries.

1. Edit Docker's daemon configuration.

cd /etc/docker
sudo nano daemon.json

2. Add the following configuration:

{
  "insecure-registries": ["<your-nexus-ip>:5000"]
}

3. Restart Docker.

sudo systemctl restart docker

4. Start the Nexus container again if it stopped.

docker start <container_id>

Step 5: Testing the Implementation

1. Log in to your private registry.

docker login <your-nexus-ip>:5000

2. Tag and push a Docker image to the Nexus repository.

docker tag hello-world:latest <your-nexus-ip>:5000/hello-world:latest
docker push <your-nexus-ip>:5000/hello-world:latest

Key Points

• We are pushing a digital representation of the image, which is significantly smaller than the full image size.

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