Turnpike slo sli

[mjholder]

SLO/SLI for turnpike:
This PR adds two sets of metrics for prometheus to scrape:

1. Auth plugin metrics.
   • Metrics exposed on localhost:5000/metrics
   • Metrics consist of response time and response code labeled per plugin
2. Nginx metrics.
   • Metrics exposed on localhost:24321/metrics
   • Metrics read from access logs of nginx which are written to a shared volume for fluentd to read
   • Metrics are labeled by method (GET, POST, etc) and status (200, 400, etc):
     • Upstream response time
     • request total duration
     • Bytes sent

To test:

• get turnpike running (docs
• upon hitting https://turnpike.example.com/api/turnpike/identity/ or any other turnpike endpoint you should see logs from web_1 and fluentd_1 printing metrics
• go to the endpoints localhost:5000/metrics and localhost:24321/metrics to see the metrics being exposed for prometheus.
• if you have a local prometheus running you can configure it to scrape those endpoints