Deploy caches with TLS

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When running DTR caches on a production environment, you should secure them with TLS. In this example we’re going to deploy a DTR cache that uses TLS.

DTR caches use the same configuration file format used by Docker Registry. You can learn more about the supported configuration in the Docker Registry documentation.

Get the TLS certificate and keys

Before deploying a DTR cache with TLS you need to get a public key certificate for the domain name were you’ll deploy the cache. You’ll also need the public and private key files for that certificate.

Once you have then, transfer those file to the host where you’ll deploy the DTR cache.

Create the cache configuration

Use SSH to log into the host where you’ll deploy the DTR cache, and navigate to the directory where you’ve stored the TLS certificate and keys.

Create the config.yml file with the following content:

version: 0.1
    enabled: true
    rootdirectory: /var/lib/registry
  addr: :5000
    certificate: /certs/dtr-cache-ca.pem
    key: /certs/dtr-cache-key.pem
      - name: downstream
          blobttl: 24h
            - originhost: https://<dtr-url>
            - /certs/dtr-ca.pem

The configuration file mentions:

  • /certs/dtr-cache-ca.pem: this is the public key certificate the cache will use
  • /certs/dtr-cache-key.pem: this is the TLS private key
  • /certs/dtr-ca.pem is the CA certificate used by DTR

Run this command to download the CA certificate used by DTR:

curl -k https://<dtr-url>/ca > dtr-ca.pem

Now that we’ve got the cache configuration file and TLS certificates, we can deploy the cache by running:

docker run --detach --restart always \
  --name dtr-cache \
  --publish 5000:5000 \
  --volume $(pwd)/dtr-cache-ca.pem:/certs/dtr-cache-ca.pem \
  --volume $(pwd)/dtr-cache-key.pem:/certs/dtr-cache-key.pem \
  --volume $(pwd)/dtr-ca.pem:/certs/dtr-ca.pem \
  --volume $(pwd)/config.yml:/config.yml \
  docker/dtr-content-cache:<version> /config.yml

Use Let’s Encrypt

You can also use Let’s Encrypt to automatically generate TLS certificates that are trusted by most clients.

Learn more about Let’s Encrypt, and how to create a configuration file that leverages it.

Where to go next

docker, dtr, tls