✨ Add support for custom cache sizes

README.md

@@ -20,6 +20,7 @@ for this to work it requires inserting a root CA certificate into system trusted
 - Expose port 3128 to the network
 - Map volume `/docker_mirror_cache` for up to 32gb of cached images from all registries
 - Map volume `/ca`, the proxy will store the CA certificate here across restarts
+- 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 `REGISTRIES`: space separated list of registries to cache; no need to include Docker Hub, its already there.
 - Env `AUTH_REGISTRIES`: space separated list of `hostname:username:password` authentication info.
   - `hostname`s listed here should be listed in the REGISTRIES environment as well, so they can be intercepted.
@@ -126,7 +127,6 @@ Yeah. Docker Inc should do it. So should NPM, Inc. Wonder why they don't. 😼
 
 - Allow using multiple credentials for DockerHub; this is possible since the `/token` request includes the wanted repo as a query string parameter.
 - Test and make auth work with quay.io, unfortunately I don't have access to it (_hint, hint, quay_)
-- Make the cache size configurable, today it's fixed at 32gb.
 - Hide the mitmproxy building code under a Docker build ARG.
 - I hope that in the future this can also be used as a "Developer Office" proxy, where many developers on a fast local network
   share a proxy for bandwidth and speed savings; work is ongoing in this direction.