Add HA Proxy metrics, fix NGINX

config/prometheus/additional_metrics.yml

+- group: HA Proxy
+  priority: 10
+  metrics:
+  - title: "Throughput"
+    y_label: "Requests / Sec"
+    required_metrics:
+      - haproxy_frontend_http_requests_total
+    weight: 1
+    queries:
+    - query_range: 'sum(rate(haproxy_frontend_http_requests_total{%{environment_filter}}[2m]))'
+      label: Total
+      unit: req / sec
+  - title: "HTTP Error Rate"
+    y_label: "Error Rate (%)"
+    required_metrics:
+      - haproxy_frontend_http_responses_total
+    weight: 1
+    queries:
+    - query_range: 'sum(rate(haproxy_frontend_http_requests_total{code="5xx",%{environment_filter}}[2m])) / sum(rate(haproxy_frontend_http_requests_total{%{environment_filter}}[2m]))'
+      label: HTTP Errors
+      unit: "%"
 - group: AWS Elastic Load Balancer
   priority: 10
   metrics:
@@ -56,7 +77,7 @@
       - nginx_responses_total
     weight: 1
     queries:
-    - query_range: 'sum(nginx_responses_total{status_code="5xx", %{environment_filter}}) / sum(nginx_responses_total{server_zone!="*", server_zone!="_", %{environment_filter}})'
+    - query_range: 'sum(rate(nginx_responses_total{status_code="5xx", %{environment_filter}}[2m])) / sum(rate(nginx_requests_total{server_zone!="*", server_zone!="_", %{environment_filter}}[2m]))'
       label: HTTP Errors
       unit: "%"
 - group: Kubernetes

doc/user/project/integrations/prometheus_library/haproxy.md

+# Monitoring HA Proxy
+> [Introduced](https://gitlab.com/gitlab-org/gitlab-ce/merge_requests/12621) in GitLab 9.4
+
+GitLab has support for automatically detecting and monitoring HA Proxy. This is provided by leveraging the [HA Proxy Exporter](https://github.com/hnlq715/nginx-vts-exporter), which translates HA Proxy statistics into a Prometheus readable form.
+
+## Metrics supported
+
+| Name | Query |
+| ---- | ----- |
+| Throughput (req/sec) | sum(rate(haproxy_frontend_http_requests_total{%{environment_filter}}[2m])) |
+| HTTP Error Rate (%) | sum(rate(haproxy_frontend_http_requests_total{code="5xx",%{environment_filter}}[2m])) / sum(rate(haproxy_frontend_http_requests_total{%{environment_filter}}[2m])) |
+
+## Configuring Prometheus to monitor for HA Proxy metrics
+
+To get started with NGINX monitoring, you should install and configure the [HA Proxy exporter](https://github.com/prometheus/haproxy_exporter) which parses these statistics and translates them into a Prometheus monitoring endpoint.
+
+## Specifying the Environment label
+
+In order to isolate and only display relevant metrics for a given environment
+however, GitLab needs a method to detect which labels are associated. To do this, GitLab will [look for an `environment` label](metrics.md#identifying-environments).

doc/user/project/integrations/prometheus_library/metrics.md

@@ -4,6 +4,7 @@
 GitLab offers automatic detection of select [Prometheus exporters](https://prometheus.io/docs/instrumenting/exporters/). Currently supported exporters are:
 * [Kubernetes](kubernetes.md)
 * [NGINX](nginx.md)
+* [HA Proxy](haproxy.md)
 * [Amazon Cloud Watch](cloudwatch.md)
 
 We have tried to surface the most important metrics for each exporter, and will be continuing to add support for additional exporters in future releases. If you would like to add support for other official exporters, [contributions](#adding-to-the-library) are welcome.