Custom Reverse Proxy

A fast and reusable reverse proxy as an alternative to serving deployments through proxies with complicated configurations like NGINX or Envoy. Especially useful for multiple service deployments on heroku, since the port changes and is dynamically configured with the PORT environment variable.

Configuration

All configuration is done through environment variables. First define the names for each service you want to proxy to:

export services="service1,service2,service3,internalmetrics" #delimited by commas

Then define the incoming back off of the proxy and outgoing URL to the remote server for each service you defined above.

export service1_incoming_path="/service1/"
export service1_outgoing_url="http://google.com"
export service2_incoming_path="/service2/"
export service2_outgoing_url="http://wikipedia.org"
export service3_incoming_path="/localFiles/"
export service3_outgoing_url="file://." # serve up this local directory
export internalmetrics_incoming_path="/metrics"

Now set the port on which you want the proxy to be served on.

export PORT=8443

A sample configuration can be found in the dev env file.

Start the service and you should see:

2019/12/15 14:04:31 read in services [service1 service2]
2019/12/15 14:04:31 read in config ([]main.proxyConfig) (len=2 cap=2) {
 (main.proxyConfig) {
  incomingPath: (string) (len=10) "/service1/",
  outgoingURL: (*url.URL)(0xc000100000)(http://google.com),
  name: (string) (len=8) "service1"
 },
 (main.proxyConfig) {
  incomingPath: (string) (len=10) "/service2/",
  outgoingURL: (*url.URL)(0xc000100080)(http://wikipedia.org),
  name: (string) (len=8) "service2"
 }
}
2019/12/15 14:04:31 Serving on port :8443
..

Make a request to where you've deployed the service and you should see the following logs saying which endpoint and service is being hit:

2019/12/15 14:06:02 service2 -- /
2019/12/15 14:06:06 service1 -- /
2019/12/15 14:06:36 service2 -- /this/is/a/sample/route

Regex and more advanced route matching rules can be applied with the rules for the golang http.HandleFunc routing rules.

Static Files (e.g. User Interfaces)

Static bundles and directories can be served up to the browser using golang's http file server. To apply this to the reverse proxy, add the following configuration values in environment:

export services="ui" # name of the ui you want
export ui_incoming_path="/services/userinterface/" # where you want the files to be served
export ui_outgoing_url="file://assets" # where the files exist locally to the reverse-proxy

Prometheus Metrics

Prometheus metrics from Prometheu's golang client can be integrated to the reverse proxy with the following configuration:

export services="internalmetrics" # exact match
export internalmetrics_incoming_path="/prometheusmetrics" # where metrics will be accessed from

Development

./watch_user_changes.sh

This will format, build, unit test, and integration test the project whenever changes are made.

Authors

• David Goldstein - DavidCharlesGoldstein.com - Decipher Technology Studios

License

This project is licensed under the MIT License - see the LICENSE.md file for details