Merge branch 'jl-update-error-rate-to-percent' into 'master'

Update NGINX error rate to a percentage

See merge request gitlab-org/gitlab-ce!19471

config/prometheus/additional_metrics.yml

@@ -29,14 +29,14 @@
       label: Pod average
       unit: ms
   - title: "HTTP Error Rate"
-    y_label: "HTTP 500 Errors / Sec"
+    y_label: "HTTP Errors"
     required_metrics:
       - nginx_upstream_responses_total
     weight: 1
     queries:
-    - query_range: 'sum(rate(nginx_upstream_responses_total{status_code="5xx", upstream=~"%{kube_namespace}-%{ci_environment_slug}-.*"}[2m]))'
-      label: HTTP Errors
-      unit: "errors / sec"
+    - query_range: 'sum(rate(nginx_upstream_responses_total{status_code="5xx", upstream=~"%{kube_namespace}-%{ci_environment_slug}-.*"}[2m])) / sum(rate(nginx_upstream_responses_total{upstream=~"%{kube_namespace}-%{ci_environment_slug}-.*"}[2m])) * 100'
+      label: 5xx Errors
+      unit: "%"
 - group: Response metrics (HA Proxy)
   priority: 10
   metrics:

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

@@ -14,7 +14,7 @@ GitLab has support for automatically detecting and monitoring the Kubernetes NGI
 | ---- | ----- |
 | Throughput (req/sec) | sum(rate(nginx_upstream_responses_total{upstream=~"%{kube_namespace}-%{ci_environment_slug}-.*"}[2m])) by (status_code) |
 | Latency (ms) | avg(nginx_upstream_response_msecs_avg{upstream=~"%{kube_namespace}-%{ci_environment_slug}-.*"}) |
-| HTTP Error Rate (HTTP Errors / sec) | sum(rate(nginx_upstream_responses_total{status_code="5xx", upstream=~"%{kube_namespace}-%{ci_environment_slug}-.*"}[2m])) |
+| HTTP Error Rate (%) | sum(rate(nginx_upstream_responses_total{status_code="5xx", upstream=~"%{kube_namespace}-%{ci_environment_slug}-.*"}[2m])) / sum(rate(nginx_upstream_responses_total{upstream=~"%{kube_namespace}-%{ci_environment_slug}-.*"}[2m])) * 100 |
 
 ## Configuring NGINX ingress monitoring