goaround

README

GoAround

HTTP load balancer that is capable of managing multiple server instances in a pool and balancing the incoming requests across those instances. If no backend instances are available a 503 error will be returned.

Make file

Building

make

Testing

make test

Running

The provided binary includes a shasum file located at ./bin/shasum to check this value on macOS you can run:

shasum -a 1 ./bin/goaround

Please ensure the sha matches prior to running or follow the directions above to build it yourself.

sudo ./bin/goaround -p 443 -b http://127.0.0.1:2702 -cacert /Users/ecook/cacert.pem -privkey /Users/ecook/privkey.pem

Flags

-p port: defaults to 3000
-b backend-address: may be passed multiple times
-n max number of connections per backend
-cacert location of certficate authority cert
-privkey location of private key
-cache enabled cache for get requests
-prometheus-port defaults to 8080

Flags

Metrics are created using promethus, They can be found at localhost:8080/metrics or whatever ports is specified via -prometheus-port

Updating backends via unix socket

Pass a comma separated list of all backends;

echo "http://localhost:3000,http://localhost:3001" | nc -U /tmp/goaround.sock

The backends previously configured will be removed and replaced with only the ones passed in the updated list.

Detailed Implementation

This service starts a web server on a user defined port, passed via -p flag, if no flag is passed the service will default to port 3000.

If you pass both a cacert and privkey, the server will terminate ssl connections.

Backend services are passed via -b flags, each backend passed will created a connection, which are managed by a pool. The connections are pushed into a buffered channel where they are retrieved when the Fetch method is called on the pool. The Fetch method will recursively pull connections from the channel until a request is completed successfully, or we run out of available connections.

Connections subscribe to a health check channel, which is pushed to if their is a change in health status for the backend. Backend services are assumed to have a /health endpoint, which will return a 200 response code. Other response codes you wish be considered healthy must return the body in the form {"state": "healthy", "message": ""}

Included Packages:

https://github.com/dgraph-io/ristretto