Prometheus behind an OAuth2-proxy

How to setup OAuth2-proxy

1. Make a copy of oauth2-proxy.example.cfg and rename it to oauth2-proxy.cfg
2. Fill in the required information (azure client id, azure client secret, azure tenant id)
3. Start the containers by executing make devenv sources="prometheus,auth/prometheus_oauth2_proxy_azure"

   If you would like to test the login flow from the browser then you need to setup TLS or start a tunnel. I usually use a tunnel (cloudflared tunnel --url http://localhost:4180). Do not forget to set the Redirect URIs on Azure's App Registration page

How to add a new Prometheus datasource with Azure Authentication enabled

1. Navigate to Grafana and login
2. Add a new Prometheus datasource
3. On the new Prometheus datasource page
   1. Set the URL
   2. Enable Azure Authentication
   3. Fill in the required fields of the Azure Authentication section
   4. Click Save & test
   5. You should get a "Data source is working" message

If you check the logs of OAuth2-proxy, you should see similar lines to this:

2023-04-19 11:29:40 172.31.0.1:55602 - d96b832a-170a-41eb-a974-6558c5ce4454 - - [2023/04/19 09:29:40] some-random-tunnel-address.trycloudflare.com GET / "/api/v1/status/buildinfo" HTTP/1.1 "Grafana/10.0.0-pre" 200 187 0.016
2023-04-19 11:29:41 172.31.0.1:55602 - db27c56a-ccd6-4cdb-a040-318113781abf - 65ac87f4-931f-4e46-9761-f8bf1ad36b48 [2023/04/19 09:29:41] some-random-tunnel-address.trycloudflare.com POST / "/api/v1/query" HTTP/1.1 "Grafana/10.0.0-pre" 200 103 0.003