go-rev-proxy

This simple project was meant to be an opportunity to play with a handful of enterprise technologies. It is a reverse proxy written in Go with support for Redis caching, Prometheus metrics, rate limiting, and distributed tracing.

Running the Application

After cloning the repo run docker-compose build && docker-compose up to build and start the application with all its supporting services. Exercise the reverse proxy by querying the application through it:

$ curl http://localhost:8080/api/fibonacci?pos=10000
2132534333
$ curl http://localhost:8080/api/echo?echo=test
test

OpenTracing

Navigate to the Jaeger UI at http://localhost:16686/ to see some traces:

Prometheus Metrics

Prometheus metrics are available in the usual spot:

$ curl http://localhost:8080/metrics
# HELP go_rev_proxy_requests_latency_ms Summary of Request Latency (ms)
# TYPE go_rev_proxy_requests_latency_ms summary
go_rev_proxy_requests_latency_ms{path="/api/echo",quantile="0.5"} 1
go_rev_proxy_requests_latency_ms{path="/api/echo",quantile="0.9"} 11
go_rev_proxy_requests_latency_ms{path="/api/echo",quantile="0.99"} 11
go_rev_proxy_requests_latency_ms_sum{path="/api/echo"} 15
go_rev_proxy_requests_latency_ms_count{path="/api/echo"} 6
go_rev_proxy_requests_latency_ms{path="/api/fibonacci",quantile="0.5"} 1
go_rev_proxy_requests_latency_ms{path="/api/fibonacci",quantile="0.9"} 300
go_rev_proxy_requests_latency_ms{path="/api/fibonacci",quantile="0.99"} 300
go_rev_proxy_requests_latency_ms_sum{path="/api/fibonacci"} 303
go_rev_proxy_requests_latency_ms_count{path="/api/fibonacci"} 6

Redis

Logging shows the impact of caching

proxy_1    | Starting Request http://backend:8080/api/echo?echo=test
proxy_1    | Caching: Miss http://backend:8080/api/echo?echo=test
proxy_1    | Ending Request http://backend:8080/api/echo?echo=test
proxy_1    | 2019/07/10 02:39:58 HTTPRequest took 11.4113ms
proxy_1    | Starting Request http://backend:8080/api/echo?echo=test
proxy_1    | Caching: Hit http://backend:8080/api/echo?echo=test
proxy_1    | Ending Request http://backend:8080/api/echo?echo=test
proxy_1    | 2019/07/10 02:39:58 HTTPRequest took 1.0331ms

Rate Limiting

Execute a bunch of requests to test rate limiting.

$ curl http://localhost:8080/api/echo?echo=test
test
$ curl http://localhost:8080/api/echo?echo=test
test
$ curl http://localhost:8080/api/echo?echo=test
test
$ curl http://localhost:8080/api/echo?echo=test
test
$ curl http://localhost:8080/api/echo?echo=test
test
$ curl http://localhost:8080/api/echo?echo=test
429 - Too Many Requests

Final Thoughts

Overall this turned into a fun project that allowed for some basic exploration of go, caching, tracing and other technologies. This code should never be used in any real world scenario. However, if you're interested in doing similar things you may find some useful sample code buried in here.

Improvements that could be made:

Respect incoming OpenTracing headers
Set outgoing OpenTracing headers
Make caching, tracing, etc. configurable

joe-elliott / go-rev-proxy