From a494c6bb4a3c1faedefbfcc3254f46721b01c1de Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Rapha=C3=ABl?= <rabadin@cisco.com>
Date: Wed, 18 Dec 2019 17:21:57 +0100
Subject: [PATCH] Add optional service replica selector (#19398)

When using a replicaset for the server (for redundancy purposes),
this allows to select which replica the service will talk to in
order to have a consistent view of the data.

Signed-off-by: rabadin <rvbadin@gmail.com>
---
 stable/prometheus/Chart.yaml                    | 2 +-
 stable/prometheus/README.md                     | 2 ++
 stable/prometheus/templates/server-service.yaml | 4 ++++
 stable/prometheus/values.yaml                   | 7 +++++++
 4 files changed, 14 insertions(+), 1 deletion(-)

diff --git a/stable/prometheus/Chart.yaml b/stable/prometheus/Chart.yaml
index 0250f4990c..b2d9f43cb8 100755
--- a/stable/prometheus/Chart.yaml
+++ b/stable/prometheus/Chart.yaml
@@ -1,6 +1,6 @@
 apiVersion: v1
 name: prometheus
-version: 9.5.5
+version: 9.5.6
 appVersion: 2.13.1
 description: Prometheus is a monitoring system and time series database.
 home: https://prometheus.io/
diff --git a/stable/prometheus/README.md b/stable/prometheus/README.md
index b4811c400b..952ec4cc1c 100644
--- a/stable/prometheus/README.md
+++ b/stable/prometheus/README.md
@@ -313,6 +313,8 @@ Parameter | Description | Default
 `server.service.servicePort` | Prometheus server service port | `80`
 `server.service.sessionAffinity` | Session Affinity for server service, can be `None` or `ClientIP` | `None`
 `server.service.type` | type of Prometheus server service to create | `ClusterIP`
+`server.service.statefulsetReplica.enabled` | If true, send the traffic from the service to only one replica of the replicaset | `false`
+`server.service.statefulsetReplica.replica` | Which replica to send the traffice to | `0`
 `server.sidecarContainers` | array of snippets with your sidecar containers for prometheus server | `""`
 `serviceAccounts.alertmanager.create` | If true, create the alertmanager service account | `true`
 `serviceAccounts.alertmanager.name` | name of the alertmanager service account to use or create | `{{ prometheus.alertmanager.fullname }}`
diff --git a/stable/prometheus/templates/server-service.yaml b/stable/prometheus/templates/server-service.yaml
index f837745119..a0c88eedd6 100644
--- a/stable/prometheus/templates/server-service.yaml
+++ b/stable/prometheus/templates/server-service.yaml
@@ -38,9 +38,13 @@ spec:
       nodePort: {{ .Values.server.service.nodePort }}
     {{- end }}
   selector:
+  {{- if and .Values.server.statefulSet.enabled .Values.server.service.statefulsetReplica.enabled }}
+    statefulset.kubernetes.io/pod-name: {{ .Release.Name }}-{{ .Values.server.name }}-{{ .Values.server.service.statefulsetReplica.replica }}
+  {{- else -}}
     {{- include "prometheus.server.matchLabels" . | nindent 4 }}
 {{- if .Values.server.service.sessionAffinity }}
   sessionAffinity: {{ .Values.server.service.sessionAffinity }}
 {{- end }}
+  {{- end }}
   type: "{{ .Values.server.service.type }}"
 {{- end -}}
diff --git a/stable/prometheus/values.yaml b/stable/prometheus/values.yaml
index 7fba509ece..51bcb7b6e6 100644
--- a/stable/prometheus/values.yaml
+++ b/stable/prometheus/values.yaml
@@ -858,6 +858,13 @@ server:
     sessionAffinity: None
     type: ClusterIP
 
+    ## If using a statefulSet (statefulSet.enabled=true), configure the
+    ## service to connect to a specific replica to have a consistent view
+    ## of the data.
+    statefulsetReplica:
+      enabled: false
+      replica: 0
+
   ## Prometheus server pod termination grace period
   ##
   terminationGracePeriodSeconds: 300