marathon-envoy-poc

Please see Relay for a more complete implementation.

Proof of Concept Discovery Service (xDS) for the Envoy proxy. This sets up Envoy as an "edge" proxy in an attempt to replace marathon-lb.

• Simple Flask app that queries Marathon
• Reuses some of the HAPROXY_ labels from marathon-lb
• Implements the Envoy v2 API available in Envoy 1.5.0+
• REST-JSON implementation (production version should probably use gRPC)
• Will implement all four xDS APIs:
  • Cluster Discovery Service (CDS)
  • Endpoint Discovery Service (EDS)
  • Listener Discovery Service (LDS)
  • Route Discovery Service (RDS)

Usage

To give this a try, you will need a running Marathon instance. You can run the Flask app using the default Flask server:

$ pip install -e .
  [...]
$ export FLASK_APP=marathon_envoy_poc
$ flask run
* Serving Flask app "marathon_envoy_poc"
* Running on http://127.0.0.1:5000/ (Press CTRL+C to quit)

You can adjust the address to the Marathon host using the MARATHON environment variable. Several other configuration options can be set using environment variables. See the config.py file for those options.

Envoy is then most easily run using Docker:

docker run --rm -it -v "$(pwd)":/mep --net=host envoyproxy/envoy:v1.5.0 \
  envoy -c /mep/bootstrap.yaml --service-node test --service-cluster test

This will use port 80/443 on your machine (or whatever ports the LDS tells Envoy to listen on). If you'd rather keep Envoy more isolated while testing, you can remove the --net=host argument and add -p 9901:9901 so that Envoy's admin interface is still available. You'll also need to update the address for the xds_cluster in bootstrap.yaml so that Envoy can reach the Flask app, wherever you are running it.