feat: expose collector.updateStrategy for the DaemonSet (#43)

Author: phitoduck

templates/daemonset.yaml

@@ -7,6 +7,10 @@ metadata:
     {{- include "better-stack-collector.labels" . | nindent 4 }}
     app.kubernetes.io/component: better-stack-collector
 spec:
+  {{- with .Values.collector.updateStrategy }}
+  updateStrategy:
+    {{- toYaml . | nindent 4 }}
+  {{- end }}
   selector:
     matchLabels:
       {{- include "better-stack-collector.selectorLabels" . | nindent 6 }}

tests/17-update-strategy.sh

@@ -0,0 +1,16 @@
+#!/usr/bin/env bash
+set -euo pipefail
+source "$(dirname "$0")/helpers.sh"
+
+output=$(render \
+  --set collector.env.COLLECTOR_SECRET=test123 \
+  --set 'collector.updateStrategy.type=RollingUpdate' \
+  --set 'collector.updateStrategy.rollingUpdate.maxUnavailable=25%' \
+  --set 'collector.updateStrategy.rollingUpdate.maxSurge=0')
+
+assert_contains "$output" 'updateStrategy:' "Missing updateStrategy block on DaemonSet"
+assert_contains "$output" 'type: RollingUpdate' "Missing updateStrategy.type"
+assert_contains "$output" 'maxUnavailable: 25%' "Missing maxUnavailable override"
+assert_contains "$output" 'maxSurge: 0' "Missing maxSurge override"
+
+pass

tests/18-no-update-strategy.sh

@@ -0,0 +1,12 @@
+#!/usr/bin/env bash
+set -euo pipefail
+source "$(dirname "$0")/helpers.sh"
+
+# Default values must not emit an updateStrategy block, so Kubernetes
+# applies its DaemonSet default and existing installs see no change.
+output=$(render --set collector.env.COLLECTOR_SECRET=test123)
+
+assert_not_contains "$output" 'updateStrategy:' \
+  "Unexpected updateStrategy block when collector.updateStrategy is unset"
+
+pass

values.yaml

@@ -44,6 +44,20 @@ collector:
   # Affinity
   affinity: {}
 
+  # DaemonSet update strategy. When left empty, Kubernetes applies its default
+  # for DaemonSets — RollingUpdate with maxUnavailable: 1 and maxSurge: 0 —
+  # which rolls one pod at a time and serializes the rollout on large clusters
+  # (e.g. ~15 min for 15 nodes, ~30 min for 32 nodes). Override to roll more
+  # pods concurrently; a percentage scales naturally with cluster size.
+  # See https://kubernetes.io/docs/concepts/workloads/controllers/daemonset/#rolling-update
+  updateStrategy: {}
+  # Example:
+  # updateStrategy:
+  #   type: RollingUpdate
+  #   rollingUpdate:
+  #     maxUnavailable: 25%
+  #     maxSurge: 0
+
   livenessProbe:
     initialDelaySeconds: 180
     periodSeconds: 60