ghProxy

ghProxy is a reverse proxy HTTP cache optimized for use with the GitHub API (https://api.github.com). It is essentially just a reverse proxy wrapper around ghCache with Prometheus instrumentation to monitor disk usage.

ghProxy is designed to reduce API token usage by allowing many components to share a single ghCache.

with Prow

While ghProxy can be used with any GitHub API client, it was designed for Prow. Prow’s GitHub client request throttling is optimized for use with ghProxy and doesn’t count requests that can be fulfilled with a cached response against the throttling limit.

Many Prow features (and soon components) require ghProxy in order to avoid rapidly consuming the API rate limit. Direct your Prow components that use the GitHub API (anything that requires the GH token secret) to use ghProxy and fall back to using the upstream API by adding the following flags:

--github-endpoint=http://ghproxy  # Replace this as needed to point to your ghProxy instance.
--github-endpoint=https://api.github.com

Deploying

A new container image is automatically built and published to gcr.io/k8s-prow/ghproxy whenever this directory is changed on the master branch. You can find a recent stable image tag and an example of how to deploy ghProxy to Kubernetes by checking out Prow’s ghProxy deployment.

Throttling algorithm

To prevent hitting GH API secondary rate limits, an additional ghProxy throttling algorithm can be configured and used. It is described here.