go-http-cache

A simple http proxy that writes data to filesystem and serves from cache. I built this tool to proxy some kubernetes endpoints for one of my projects. Sharing this as it might be useful for use cases where you want to serve from a persistent location and only delegate to target when data is not there.

Considerations

Writing a filter on Envoy would have been ok but this was one much easier to write and add features to. This behaviour could definitely be incorporated into Envoy.

Overrides

Following environment variables can be provided to override the default behaviour.

Name	Purpose	Default
CONFIG_FILE	Config File to be used	./conf/config.yaml
LISTEN_ADDRESS	Address this server will listen on	8070
TARGET	Proxy Target to call when cache does not have data	http://localhost:8080
IGNORE_HEADERS	Whether to consider header keys and values when looking up cache. Each header is computed when determining cache key	false
LOG_REQUEST_HEADERS	Whether to log request headers into cached data file. Be careful if you are using Auth Tokens	false
SKIP_VERIFY_TLS	Whether to verify certs for https calls	false

Running Locally

TARGET=https://jsonplaceholder.typicode.com SKIP_VERIFY_TLS=true go run app.go

Doing this will listen on 8070 and proxy calls to 8080. Filesystem path /tmp/cache is used as cache location from which subsequent responses will be served.

Container

Same thing can be run in docker like this.

docker run -e TARGET=https://jsonplaceholder.typicode.com \
-e LISTEN_ADDRESS=0.0.0.0:8070 \
-e LOG_REQUEST_HEADERS=true \
-e SKIP_VERIFY_TLS=true -p 8070:8070 \
-it skhatri/go-http-cache:latest

Test it by doing a curl http://localhost:8070/todos

Use Cases

• A temporary http proxy to capture some important http calls which you want to avoid at other times for cost/resource reasons