The main symptom is `Error response from daemon: toomanyrequests: Too Many Requests. Please see https://docs.docker.com/docker-hub/download-rate-limit/` during pulls.
Many unknowing Kubernetes clusters will hit the limit, and struggle to configure `imagePullSecrets` and `imagePullPolicy`.
Since version `0.6.0`, this proxy can be configured with the env var `ENABLE_MANIFEST_CACHE=true` which provides
configurable caching of the manifest requests that DockerHub throttles. You can then fine-tune other parameters to your needs.
Together with the possibility to centrally inject authentication (since 0.3x), this is probably one of the best ways to bring relief to your distressed cluster, while at the same time saving lots of bandwidth and time.
Note: enabling manifest caching, in its default config, effectively makes some tags **immutable**. Use with care. The configuration ENVs are explained in the [Dockerfile](./Dockerfile), relevant parts included below.
```dockerfile
# Manifest caching tiers. Disabled by default, to mimick 0.4/0.5 behaviour.
# Setting it to true enables the processing of the ENVs below.
# Once enabled, it is valid for all registries, not only DockerHub.
# The envs *_REGEX represent a regex fragment, check entrypoint.sh to understand how they're used (nginx ~ location, PCRE syntax).
ENV ENABLE_MANIFEST_CACHE="false"
# 'Primary' tier defaults to 10m cache for frequently used/abused tags.
# - People publishing to production via :latest (argh) will want to include that in the regex
# - Heavy pullers who are being ratelimited but don't mind getting outdated manifests should (also) increase the cache time here
Essentially, it's a [man in the middle](https://en.wikipedia.org/wiki/Man-in-the-middle_attack): an intercepting proxy based on `nginx`, to which all docker traffic is directed using the `HTTPS_PROXY` mechanism and injected CA root certificates.
The main feature is Docker layer/image caching, including layers served from S3, Google Storage, etc.
As a bonus it allows for centralized management of Docker registry credentials, which can in itself be the main feature, eg in Kubernetes environments.
- Production/stable is `0.6.0`, see [0.6.0 tag on Github](https://github.com/rpardini/docker-registry-proxy/tree/0.6.0) - this image is multi-arch amd64/arm64
- The previous version is `0.5.0`, without any manifest caching, see [0.5.0 tag on Github](https://github.com/rpardini/docker-registry-proxy/tree/0.5.0) - this image is multi-arch amd64/arm64
- Env `CACHE_MAX_SIZE` (default `32g`): set the max size to be used for caching local Docker image layers. Use [Nginx sizes](http://nginx.org/en/docs/syntax.html).
- Env `AUTH_REGISTRIES_DELIMITER` to change the separator between authentication info. By default, a space: "` `". If you use keys that contain spaces (as with Google Cloud Registry), you should update this variable, e.g. setting it to `AUTH_REGISTRIES_DELIMITER=";;;"`. In that case, `AUTH_REGISTRIES` could contain something like `registry1.com:user1:pass1;;;registry2.com:user2:pass2`.
- Env `AUTH_REGISTRY_DELIMITER` to change the separator between authentication info *parts*. By default, a colon: "`:`". If you use keys that contain single colons, you should update this variable, e.g. setting it to `AUTH_REGISTRIES_DELIMITER=":::"`. In that case, `AUTH_REGISTRIES` could contain something like `registry1.com:::user1:::pass1 registry2.com:::user2:::pass2`.
GitLab may use a different/separate domain to handle the authentication procedure.
Just like DockerHub uses `auth.docker.io`, GitLab uses its primary (git) domain for the authentication.
If you run GitLab on `git.example.com` and its registry on `reg.example.com`, you need to include both in `REGISTRIES` and use the primary domain for `AUTH_REGISTRIES`.
For GitLab.com itself the authentication domain should be `gitlab.com`.
```bash
docker run --rm --name docker_registry_proxy -it \
For Google Container Registry (GCR), username should be `_json_key` and the password should be the contents of the service account JSON.
Check out [GCR docs](https://cloud.google.com/container-registry/docs/advanced-authentication#json_key_file).
The service account key is in JSON format, it contains spaces ("` `") and colons ("`:`").
To be able to use GCR you should set `AUTH_REGISTRIES_DELIMITER` to something different than space (e.g. `AUTH_REGISTRIES_DELIMITER=";;;"`) and `AUTH_REGISTRY_DELIMITER` to something different than a single colon (e.g. `AUTH_REGISTRY_DELIMITER=":::"`).
Since `0.4` there is a separate `-debug` version of the image, which includes `nginx-debug`, and (since 0.5.x) has a `mitmproxy` (actually `mitmweb`) inserted after the CONNECT proxy but before the caching logic, and a second `mitmweb` between the caching layer and DockerHub.
This allows very in-depth debugging. Use sparingly, and definitely not in production.
- If you authenticate to a private registry and pull through the proxy, those images will be served to any client that can reach the proxy, even without authentication. *beware*
- [ ] "Developer Office" proxy scenario, where many developers on a fast LAN share a proxy for bandwidth and speed savings (already works for pulls, but messes up pushes, which developers tend to use a lot)
