From b13e2442b117d5f76a054e471260bff27bbf29d5 Mon Sep 17 00:00:00 2001
From: Kevin Leimkuhler <kevin@kleimkuhler.com>
Date: Thu, 16 Apr 2020 16:49:11 -0700
Subject: [PATCH] Add rolling update strategy to multi-replica pods (#4267)

This introduces a rolling update strategy to Linkerd deployments that have
three replicas during HA deployments. This allows for at most one pod to begin
terminating before a new pod ready is ready.

This allows for upgrades to take place on three node clusters. As a pod begins
terminating, it opens up the node for the new pod to start initializing.

`.Values.enablePodAntiAffinity` was chosen as the conditional here because it
is set by the `values-ha.yaml` config on HA deployments
---
 charts/linkerd2/templates/controller.yaml     | 5 +++++
 charts/linkerd2/templates/destination.yaml    | 5 +++++
 charts/linkerd2/templates/identity.yaml       | 5 +++++
 charts/linkerd2/templates/proxy-injector.yaml | 5 +++++
 charts/linkerd2/templates/sp-validator.yaml   | 5 +++++
 charts/linkerd2/templates/tap.yaml            | 5 +++++
 6 files changed, 30 insertions(+)

diff --git a/charts/linkerd2/templates/controller.yaml b/charts/linkerd2/templates/controller.yaml
index d871a1f42..a7d72a4df 100644
--- a/charts/linkerd2/templates/controller.yaml
+++ b/charts/linkerd2/templates/controller.yaml
@@ -45,6 +45,11 @@ spec:
       {{.Values.global.controllerComponentLabel}}: controller
       {{.Values.global.controllerNamespaceLabel}}: {{.Values.global.namespace}}
       {{- include "partials.proxy.labels" .Values.global.proxy | nindent 6}}
+  {{- if .Values.enablePodAntiAffinity }}
+  strategy:
+    rollingUpdate:
+      maxUnavailable: 1
+  {{- end }}
   template:
     metadata:
       annotations:
diff --git a/charts/linkerd2/templates/destination.yaml b/charts/linkerd2/templates/destination.yaml
index 4a55d35aa..8914b8b62 100644
--- a/charts/linkerd2/templates/destination.yaml
+++ b/charts/linkerd2/templates/destination.yaml
@@ -45,6 +45,11 @@ spec:
       {{.Values.global.controllerComponentLabel}}: destination
       {{.Values.global.controllerNamespaceLabel}}: {{.Values.global.namespace}}
       {{- include "partials.proxy.labels" .Values.global.proxy | nindent 6}}
+  {{- if .Values.enablePodAntiAffinity }}
+  strategy:
+    rollingUpdate:
+      maxUnavailable: 1
+  {{- end }}
   template:
     metadata:
       annotations:
diff --git a/charts/linkerd2/templates/identity.yaml b/charts/linkerd2/templates/identity.yaml
index 45210f492..7bfd30085 100644
--- a/charts/linkerd2/templates/identity.yaml
+++ b/charts/linkerd2/templates/identity.yaml
@@ -65,6 +65,11 @@ spec:
       {{.Values.global.controllerComponentLabel}}: identity
       {{.Values.global.controllerNamespaceLabel}}: {{.Values.global.namespace}}
       {{- include "partials.proxy.labels" .Values.global.proxy | nindent 6}}
+  {{- if .Values.enablePodAntiAffinity }}
+  strategy:
+    rollingUpdate:
+      maxUnavailable: 1
+  {{- end }}
   template:
     metadata:
       annotations:
diff --git a/charts/linkerd2/templates/proxy-injector.yaml b/charts/linkerd2/templates/proxy-injector.yaml
index ccaa5063f..4759f2399 100644
--- a/charts/linkerd2/templates/proxy-injector.yaml
+++ b/charts/linkerd2/templates/proxy-injector.yaml
@@ -24,6 +24,11 @@ spec:
   selector:
     matchLabels:
       {{.Values.global.controllerComponentLabel}}: proxy-injector
+  {{- if .Values.enablePodAntiAffinity }}
+  strategy:
+    rollingUpdate:
+      maxUnavailable: 1
+  {{- end }}
   template:
     metadata:
       annotations:
diff --git a/charts/linkerd2/templates/sp-validator.yaml b/charts/linkerd2/templates/sp-validator.yaml
index b9278d6b2..8d1e0f325 100644
--- a/charts/linkerd2/templates/sp-validator.yaml
+++ b/charts/linkerd2/templates/sp-validator.yaml
@@ -43,6 +43,11 @@ spec:
   selector:
     matchLabels:
       {{.Values.global.controllerComponentLabel}}: sp-validator
+  {{- if .Values.enablePodAntiAffinity }}
+  strategy:
+    rollingUpdate:
+      maxUnavailable: 1
+  {{- end }}
   template:
     metadata:
       annotations:
diff --git a/charts/linkerd2/templates/tap.yaml b/charts/linkerd2/templates/tap.yaml
index 08fcd9daa..40209f58d 100644
--- a/charts/linkerd2/templates/tap.yaml
+++ b/charts/linkerd2/templates/tap.yaml
@@ -48,6 +48,11 @@ spec:
       {{.Values.global.controllerComponentLabel}}: tap
       {{.Values.global.controllerNamespaceLabel}}: {{.Values.global.namespace}}
       {{- include "partials.proxy.labels" .Values.global.proxy | nindent 6}}
+  {{- if .Values.enablePodAntiAffinity }}
+  strategy:
+    rollingUpdate:
+      maxUnavailable: 1
+  {{- end }}
   template:
     metadata:
       annotations: