From 4a6067e71429728da25a1faa331b9d3262eae6df Mon Sep 17 00:00:00 2001
From: Julien Mailleret <8582351+jmlrt@users.noreply.github.com>
Date: Mon, 29 Jun 2020 21:18:10 +0200
Subject: [PATCH] [logstash] add headless service for statefulset (#695)

This commit add a mandatory headless service for Logstash statefulset.

Headless service is required for Statefulsets.
While Helm 2 allowed to deploy Statefulsets without a serviceName, Helm 3 enforce this requirement and fails if serviceName is missing.

Note: Statefulsets don't accept serviceName field update during release upgrades. This change is therefore considered as a breaking change and will require using `helm upgrade --force` for upgrades.
---
 logstash/templates/service-headless.yaml | 23 +++++++++++++++++++++++
 logstash/templates/statefulset.yaml      |  6 ++----
 logstash/tests/logstash_test.py          |  5 +++--
 3 files changed, 28 insertions(+), 6 deletions(-)
 create mode 100644 logstash/templates/service-headless.yaml

diff --git a/logstash/templates/service-headless.yaml b/logstash/templates/service-headless.yaml
new file mode 100644
index 000000000..2bf840b34
--- /dev/null
+++ b/logstash/templates/service-headless.yaml
@@ -0,0 +1,23 @@
+---
+kind: Service
+apiVersion: v1
+metadata:
+  name: "{{ template "logstash.fullname" . }}-headless"
+  labels:
+    app: "{{ template "logstash.fullname" . }}"
+    chart: "{{ .Chart.Name }}"
+    heritage: {{ .Release.Service | quote }}
+    release: {{ .Release.Name | quote }}
+{{- if .Values.labels }}
+{{ toYaml .Values.labels | indent 4 }}
+{{- end }}
+spec:
+  clusterIP: None
+  selector:
+    app: "{{ template "logstash.fullname" . }}"
+  ports:
+  - name: http
+    port: {{ .Values.httpPort }}
+{{- if .Values.extraPorts }}
+{{- toYaml .Values.extraPorts | nindent 2 }}
+{{- end }}
diff --git a/logstash/templates/statefulset.yaml b/logstash/templates/statefulset.yaml
index 30dbb062f..18811ed21 100644
--- a/logstash/templates/statefulset.yaml
+++ b/logstash/templates/statefulset.yaml
@@ -12,9 +12,7 @@ metadata:
     {{ $key }}: {{ $value | quote }}
     {{- end }}
 spec:
-  {{- if .Values.service }}
-  serviceName: {{ template "logstash.fullname" . }}
-  {{- end }}
+  serviceName: {{ template "logstash.fullname" . }}-headless
   selector:
     matchLabels:
       app: "{{ template "logstash.fullname" . }}"
@@ -151,7 +149,7 @@ spec:
         - name: http
           containerPort: {{ .Values.httpPort }}
       {{- if .Values.extraPorts }}
-        {{- toYaml .Values.extraPorts | nindent 8 }}  
+        {{- toYaml .Values.extraPorts | nindent 8 }}
       {{- end }}
         resources:
 {{ toYaml .Values.resources | indent 10 }}
diff --git a/logstash/tests/logstash_test.py b/logstash/tests/logstash_test.py
index 07bd7c877..7aa81e69f 100755
--- a/logstash/tests/logstash_test.py
+++ b/logstash/tests/logstash_test.py
@@ -78,8 +78,9 @@ def test_defaults():
     )
 
     # Service
-    assert "serviceName" not in r["statefulset"][name]["spec"]
-    assert "service" not in r
+    assert r["statefulset"][name]["spec"]["serviceName"] == name + "-headless"
+    assert name + "-headless" in r["service"]
+    assert r["service"][name + "-headless"]["spec"]["ports"][0]["port"] == 9600
 
     # Other
     assert r["statefulset"][name]["spec"]["template"]["spec"]["securityContext"] == {