Self-hosted Docker Registry with Cloudflare R2 (S3-compatible) as Backend

Cloudflare R2 is an S3-compatible object storage with 10GB / month free storage for free tier.

Assume you have created bucket and API access already in Cloudflare R2.

config file (/data/appdata/docker-registry-s3/config.yml):

version: 0.1
log:
  accesslog:
    disabled: false
  level: info
  fields:
    service: registry
storage:
  cache:
    blobdescriptor: inmemory
#  filesystem:
#    rootdirectory: /var/lib/registry
  s3:
    accesskey: UPDATE-ME
    secretkey: UPDATE-ME
    region: apac
    forcepathstyle: true
    regionendpoint: https://UPDATE-ME.r2.cloudflarestorage.com
    bucket: docker-registry
    chunksize: 104857600
    multipartcopychunksize: 33554432
    multipartcopymaxconcurrency: 100
    multipartcopythresholdsize: 33554432
    # rootdirectory: /s3/object/name/prefix
http:
  addr: :5000
  headers:
    X-Content-Type-Options: [nosniff]
# health:
#   storagedriver:
#     enabled: true
#     interval: 10s
#     threshold: 3

If you saw this error in the logs “unknown error completing upload: InvalidPart: All non-trailing parts must have the same length.”, it can be fixed by updating chunksize setting above (already updated).
source: https://community.cloudflare.com/t/all-non-trailing-parts-must-have-the-same-length/552190/8

docker command:

docker run -d 
  -p 5000:5000 \
  --restart=always \
  --name docker-registry-s3 \
  -v /data/appdata/docker-registry-s3/config.yml:/etc/docker/registry/config.yml \
  registry:2

For troubleshooting:

To use aws-cli with Cloudflare R2:

export AWS_ACCESS_KEY_ID=UPDATE-ME
export AWS_SECRET_ACCESS_KEY=UPDATE-ME
export AWS_ENDPOINT_URL=https://UPDATE-ME.r2.cloudflarestorage.com

aws s3 ls s3://docker-registry

To check if your registry is running correctly: visiting http://localhost:5000/v2/_catalog and you should see JSON payload list all your repositories.

The default path strcture for registry in s3 bucket is: /docker/registry/v2/{blobs,repositories}

Reference Links:

Cloudflare R2 Documentation

Docker Registry Documentation (see Configuration & S3 storage driver section)