Include Prometheus and Grafana setup in README

README.md

@@ -232,6 +232,35 @@ The app is currently internationalized. It is only localized to U.S. English. To
 `cd apps/block_scout_web; mix gettext.extract --merge; cd -`
 2. To edit the new strings, go to `apps/block_scout_web/priv/gettext/en/LC_MESSAGES/default.po`.
 
+## Metrics
+
+BlockScout is setup to export [Prometheus](https://prometheus.io/) metrics at `/metrics`.
+
+### Prometheus
+
+1. Install prometheus: `brew install prometheus`
+2. Start the web server `iex -S mix phx.server`
+3. Start prometheus: `prometheus --config.file=prometheus.yml`
+
+### Grafana
+
+1. Install grafana: `brew install grafana`
+2. Install Pie Chart panel plugin: `grafana-cli plugins install grafana-piechart-panel`
+3. Start grafana: `brew services start grafana`
+4. Add Prometheus as a Data Source
+   1. `open http://localhost:3000/datasources`
+   2. Click "+ Add data source"
+   3. Put "Prometheus" for "Name"
+   4. Change "Type" to "Prometheus"
+   5. Set "URL" to "http://localhost:9090"
+   6. Set "Scrape Interval" to "10s"
+5. Add the dashboards from https://github.com/deadtrickster/beam-dashboards:
+   For each `*.json` file in the repo.
+   1. `open http://localhost:3000/dashboard/import`
+   2. Copy the contents of the JSON file in the "Or paste JSON" entry
+   3. Click "Load"
+6. View the dashboards.  (You will need to click-around and use BlockScout for the web-related metrics to show up.)
+
 ## Acknowledgements
 
 We would like to thank the [EthPrize foundation](http://ethprize.io/) for their funding support.