From d32d24779bb4241d35b0879cbd96bec361841a49 Mon Sep 17 00:00:00 2001
From: Clement Chevalier <69809982+clemcvlcs@users.noreply.github.com>
Date: Thu, 28 Jan 2021 12:41:19 +0100
Subject: [PATCH] [filebeat] variable maxUnavailable updateStrategy (#809)

---
 filebeat/README.md                |  2 ++
 filebeat/templates/daemonset.yaml |  4 ++++
 filebeat/tests/filebeat_test.py   | 23 ++++++++++++++++++++++-
 filebeat/values.yaml              |  2 ++
 4 files changed, 30 insertions(+), 1 deletion(-)

diff --git a/filebeat/README.md b/filebeat/README.md
index 701c136a2..0d4dbfeed 100644
--- a/filebeat/README.md
+++ b/filebeat/README.md
@@ -110,6 +110,7 @@ as a reference. They are also used in the automated testing of this chart.
 | `daemonset.hostAliases`        | Configurable [hostAliases][] for filebeat DaemonSet                                                                                                                          | `[]`                               |
 | `daemonset.hostNetworking`     | Enable filebeat DaemonSet to use `hostNetwork`                                                                                                                               | `false`                            |
 | `daemonset.filebeatConfig`     | Allows you to add any config files in `/usr/share/filebeat` such as `filebeat.yml` for filebeat DaemonSet                                                                    | see [values.yaml][]                |
+| `daemonset.maxUnavailable`     | The [maxUnavailable][] value for the pod disruption budget. By default this will prevent Kubernetes from having more than 1 unhealthy pod in the node group                  | `1`                                |
 | `daemonset.nodeSelector`       | Configurable [nodeSelector][] for filebeat DaemonSet                                                                                                                         | `{}`                               |
 | `daemonset.secretMounts`       | Allows you easily mount a secret as a file inside the DaemonSet. Useful for mounting certificates and other secrets. See [values.yaml][] for an example                      | `[]`                               |
 | `daemonset.podSecurityContext` | Configurable [podSecurityContext][] for filebeat DaemonSet pod execution environment                                                                                         | see [values.yaml][]                |
@@ -261,6 +262,7 @@ about our development and testing process.
 [kafka output]: https://www.elastic.co/guide/en/beats/filebeat/6.8/kafka-output.html
 [kubernetes secrets]: https://kubernetes.io/docs/concepts/configuration/secret/
 [labels]: https://kubernetes.io/docs/concepts/overview/working-with-objects/labels/
+[maxUnavailable]: https://kubernetes.io/docs/tasks/run-application/configure-pdb/#specifying-a-poddisruptionbudget
 [nodeSelector]: https://kubernetes.io/docs/concepts/configuration/assign-pod-node/#nodeselector
 [podSecurityContext]: https://kubernetes.io/docs/tasks/configure-pod-container/security-context/
 [priorityClass]: https://kubernetes.io/docs/concepts/configuration/pod-priority-preemption/#priorityclass
diff --git a/filebeat/templates/daemonset.yaml b/filebeat/templates/daemonset.yaml
index 3515d8ca5..732840f2e 100644
--- a/filebeat/templates/daemonset.yaml
+++ b/filebeat/templates/daemonset.yaml
@@ -30,6 +30,10 @@ spec:
       app: "{{ template "filebeat.fullname" . }}"
       release: {{ .Release.Name | quote }}
   updateStrategy:
+    {{- if eq .Values.updateStrategy "RollingUpdate" }}
+    rollingUpdate:
+      maxUnavailable: {{ .Values.daemonset.maxUnavailable }}
+    {{- end }}
     type: {{ .Values.updateStrategy }}
   template:
     metadata:
diff --git a/filebeat/tests/filebeat_test.py b/filebeat/tests/filebeat_test.py
index 9460e8ec6..0a1c100dc 100644
--- a/filebeat/tests/filebeat_test.py
+++ b/filebeat/tests/filebeat_test.py
@@ -51,6 +51,13 @@ def test_defaults():
 
     assert r["daemonset"][name]["spec"]["updateStrategy"]["type"] == "RollingUpdate"
 
+    assert (
+        r["daemonset"][name]["spec"]["updateStrategy"]["rollingUpdate"][
+            "maxUnavailable"
+        ]
+        == 1
+    )
+
     assert (
         r["daemonset"][name]["spec"]["template"]["spec"]["serviceAccountName"] == name
     )
@@ -404,7 +411,21 @@ def test_adding_deprecated_tolerations():
 
 def test_override_the_default_update_strategy():
     config = """
-updateStrategy: OnDelete
+    daemonset:
+      maxUnavailable: 2
+"""
+
+    r = helm_template(config)
+    assert r["daemonset"][name]["spec"]["updateStrategy"]["type"] == "RollingUpdate"
+    assert (
+        r["daemonset"][name]["spec"]["updateStrategy"]["rollingUpdate"][
+            "maxUnavailable"
+        ]
+        == 2
+    )
+
+    config = """
+    updateStrategy: OnDelete
 """
 
     r = helm_template(config)
diff --git a/filebeat/values.yaml b/filebeat/values.yaml
index dfcd8f546..ac4b8df4e 100755
--- a/filebeat/values.yaml
+++ b/filebeat/values.yaml
@@ -36,6 +36,8 @@ daemonset:
       output.elasticsearch:
         host: '${NODE_NAME}'
         hosts: '${ELASTICSEARCH_HOSTS:elasticsearch-master:9200}'
+  # Only used when updateStrategy is set to "RollingUpdate"
+  maxUnavailable: 1
   nodeSelector: {}
   # A list of secrets and their paths to mount inside the pod
   # This is useful for mounting certificates for security other sensitive values