Docker Registry Setup (Standalone, with Docker Compose)

This guide explains how to run a Docker registry using Docker Compose and configure K3s to allow insecure (HTTP) registry access for large image uploads.

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1. Prerequisites

• Docker and Docker Compose installed
• (Optional) Self-signed certificates if you want HTTPS (see generate-certs.sh)

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2. Setup Registry with Docker Compose

1. Clone or copy the files to your server:

   • docker-compose.yml
   • config.yml
   • certs/ (if using HTTPS)

2. Create the data directory:

   sudo mkdir -p /opt/docker-registry-data
   sudo chown $USER:$USER /opt/docker-registry-data

3. Start the registry:

   docker compose up -d

   • By default, this runs the registry on port 5000 (HTTP)
   • For HTTPS, update docker-compose.yml and config.yml to use port 443 and provide certs

4. Test the registry:

   curl http://localhost:5000/v2/
   # Should return {}

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3. Configure Docker to Allow Insecure Registry

Add the following to /etc/docker/daemon.json:

{
  "insecure-registries": ["localhost:5000", "yourdomainname.com:5000"]
}

Then restart Docker:

sudo systemctl restart docker

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4. Configure K3s to Allow Insecure Registry (optional)

Add the following to /etc/rancher/k3s/registries.yaml:

mirrors:
  "yourdomainname.com:5000":
    endpoint:
      - "http://yourdomainname.com:5000"

Then restart K3s:

sudo systemctl restart k3s

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5. Tag and Push Images

Tag your image for the registry:

docker tag <local-image> yourdomainname.com:5000/<image-name>:<tag>

Push the image:

docker push yourdomainname.com:5000/<image-name>:<tag>

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6. Troubleshooting

• If you see http: server gave HTTP response to HTTPS client, it means the registry is running on HTTP but the client expects HTTPS. Make sure the registry and all configs use HTTP if you don't use TLS.
• For large uploads, ensure timeouts are set high in config.yml and Docker Compose.
• If you change ports, update all references in configs and /etc/hosts as needed.

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7. References

• Docker Registry Documentation
• K3s Registry Configuration