From ae939d0183aead85d4f10450e1893b34e2f4a199 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Henrik=20Reinst=C3=A4dtler?=
 <reinstaedtler@stud.uni-heidelberg.de>
Date: Sat, 5 Jun 2021 22:59:56 +0200
Subject: [PATCH] prometheus_exporter installed and initial docu written

---
 Gemfile                                    |  1 +
 Gemfile.lock                               |  4 +++
 MONITORING.md                              | 30 ++++++++++++++++++++++
 config/initializers/prometheus_exporter.rb |  7 +++++
 4 files changed, 42 insertions(+)
 create mode 100644 MONITORING.md
 create mode 100644 config/initializers/prometheus_exporter.rb

diff --git a/Gemfile b/Gemfile
index 4e5004155..b59c17eaf 100644
--- a/Gemfile
+++ b/Gemfile
@@ -144,3 +144,4 @@ end
 group :test, :development, :docker_development do
   gem 'cypress-on-rails', '~> 1.0'
 end
+gem 'prometheus_exporter'
\ No newline at end of file
diff --git a/Gemfile.lock b/Gemfile.lock
index 31dda743f..8ba34f558 100644
--- a/Gemfile.lock
+++ b/Gemfile.lock
@@ -383,6 +383,8 @@ GEM
     progress_bar (1.3.3)
       highline (>= 1.6, < 3)
       options (~> 2.3.0)
+    prometheus_exporter (0.7.0)
+      webrick
     public_suffix (4.0.6)
     puma (4.3.7)
       nio4r (~> 2.0)
@@ -606,6 +608,7 @@ GEM
       rack-proxy (>= 0.6.1)
       railties (>= 5.2)
       semantic_range (>= 2.3.0)
+    webrick (1.7.0)
     websocket-driver (0.7.3)
       websocket-extensions (>= 0.1.0)
     websocket-extensions (0.1.5)
@@ -668,6 +671,7 @@ DEPENDENCIES
   pgreset
   premailer-rails
   progress_bar
+  prometheus_exporter
   puma (~> 4.1)
   rack
   rails (~> 6.1)
diff --git a/MONITORING.md b/MONITORING.md
new file mode 100644
index 000000000..9477a5b4c
--- /dev/null
+++ b/MONITORING.md
@@ -0,0 +1,30 @@
+# Monitoring
+
+## Getting started (development mode): Setting up prometheus & grafana
+
+0. Start prometheus_exporter in the mampf container
+`sudo docker-compose exec mampf prometheus_exporter -b 0.0.0.0`
+1. Setup prometheus in development
+
+```sh
+cd docker/development
+sudo docker run -d \
+-p 9090:9090 \
+--name prometheus -v $(pwd)/prometheus.yml:/etc/prometheus/prometheus.yml \
+prom/prometheus
+# Add to mampf dev network
+sudo docker network connect development_default prometheus
+```
+2. setup Grafana:
+
+```sh
+sudo docker run -d \                                      
+-p 2345:2345 \
+--name grafana \
+-e "GF_SERVER_HTTP_PORT=2345" \
+grafana/grafana
+```
+3. Now visit localhost:2345 and configure the datasource (`prometheus:9090`)
+4.  Setup the dashboard, interisting metrics:
+  - `rate(ruby_collector_sessions_total[5m])`
+  - `rate(ruby_http_requests_total[5m])`
\ No newline at end of file
diff --git a/config/initializers/prometheus_exporter.rb b/config/initializers/prometheus_exporter.rb
new file mode 100644
index 000000000..a1793c0a7
--- /dev/null
+++ b/config/initializers/prometheus_exporter.rb
@@ -0,0 +1,7 @@
+# in config/initializers/prometheus.rb
+if Rails.env != "test"
+    require 'prometheus_exporter/middleware'
+  
+    # This reports stats per request like HTTP status and timings
+    Rails.application.middleware.unshift PrometheusExporter::Middleware
+  end
\ No newline at end of file