fix(8.8): back Web Modeler restapi /tmp with a per-pod ephemeral volume (#6408)

Co-authored-by: Claude Opus 4.8 <noreply@anthropic.com>
Co-authored-by: distro-ci[bot] <122795778+distro-ci[bot]@users.noreply.github.com>

Author: 3 people

charts/camunda-platform-8.8/README.md

@@ -4,7 +4,7 @@
 {{- fail "webModeler.persistence.deploymentStrategy value must be one of 'RollingUpdate', 'Recreate'" -}}
 {{- end -}}
 {{- if and (eq $deploymentStrategy "Recreate") (not .Values.webModeler.persistence.enabled) -}}
-{{- fail "webModeler.persistence.deploymentStrategy: Recreate requires webModeler.persistence.enabled: true (it avoids a Multi-Attach deadlock on the chart-managed RWO PVC; without persistence it only adds upgrade downtime)" -}}
+{{- fail "webModeler.persistence.deploymentStrategy: Recreate requires webModeler.persistence.enabled: true. The default chart-managed path uses a per-pod ephemeral volume with no Multi-Attach contention, so Recreate is only useful when existingClaim points to a ReadWriteOnce volume; without persistence it only adds upgrade downtime" -}}
 {{- end -}}
 apiVersion: apps/v1
 kind: Deployment
@@ -202,8 +202,23 @@ spec:
           persistentVolumeClaim:
             claimName: {{ .Values.webModeler.persistence.existingClaim }}
           {{- else if .Values.webModeler.persistence.enabled }}
-          persistentVolumeClaim:
-            claimName: {{ include "camundaPlatform.fullname" . }}-webmodeler-data
+          ephemeral:
+            volumeClaimTemplate:
+              {{- with .Values.webModeler.persistence.annotations }}
+              metadata:
+                annotations: {{- toYaml . | nindent 18 }}
+              {{- end }}
+              spec:
+                accessModes: {{ .Values.webModeler.persistence.accessModes | default (list "ReadWriteOnce") | toYaml | nindent 18 }}
+                {{- with .Values.webModeler.persistence.storageClassName }}
+                storageClassName: {{ . | quote }}
+                {{- end }}
+                {{- with .Values.webModeler.persistence.selector }}
+                selector: {{- toYaml . | nindent 18 }}
+                {{- end }}
+                resources:
+                  requests:
+                    storage: {{ .Values.webModeler.persistence.size | default "1Gi" | quote }}
           {{- else }}
           emptyDir: {}
           {{- end }}

charts/camunda-platform-8.8/templates/web-modeler/deployment-restapi.yaml

@@ -107,9 +107,12 @@ func (s *PersistenceTemplateTest) TestPersistenceConfiguration() {
 
 				// then
 				s.Require().NotNil(tmpVolume, "tmp volume should exist")
-				s.Require().NotNil(tmpVolume.PersistentVolumeClaim, "should use PVC when persistence is enabled")
+				s.Require().NotNil(tmpVolume.Ephemeral, "should use a per-pod ephemeral volume when persistence is enabled")
 				s.Require().Nil(tmpVolume.EmptyDir, "should not use emptyDir when persistence is enabled")
-				s.Require().Equal("camunda-platform-test-webmodeler-data", tmpVolume.PersistentVolumeClaim.ClaimName)
+				s.Require().Nil(tmpVolume.PersistentVolumeClaim, "should not reference a shared PVC when persistence is enabled")
+				spec := tmpVolume.Ephemeral.VolumeClaimTemplate.Spec
+				s.Require().Equal("5Gi", spec.Resources.Requests.Storage().String())
+				s.Require().Equal(corev1.ReadWriteOnce, spec.AccessModes[0])
 			},
 		},
 		{
@@ -178,39 +181,10 @@ func (s *PersistenceTemplateTest) TestPersistenceConfiguration() {
 	}
 }
 
-func TestPVCManifestCreated(t *testing.T) {
-	t.Parallel()
-
-	chartPath, err := filepath.Abs("../../../")
-	require.NoError(t, err)
-
-	testCase := testhelpers.TestCase{
-		Name: "TestPVCManifestCreated",
-		Values: map[string]string{
-			"identity.enabled":                      "true",
-			"webModeler.enabled":                    "true",
-			"webModeler.restapi.mail.fromAddress":   "test@test.com",
-			"webModeler.persistence.enabled":        "true",
-			"webModeler.persistence.size":           "5Gi",
-			"webModeler.persistence.accessModes[0]": "ReadWriteOnce",
-		},
-		Verifier: func(t *testing.T, output string, err error) {
-			var pvc corev1.PersistentVolumeClaim
-			helm.UnmarshalK8SYaml(t, output, &pvc)
-			require.Equal(t, "camunda-platform-test-webmodeler-data", pvc.Name)
-			require.Equal(t, "5Gi", pvc.Spec.Resources.Requests.Storage().String())
-			require.Equal(t, corev1.ReadWriteOnce, pvc.Spec.AccessModes[0])
-		},
-	}
-
-	testhelpers.RunTestCasesE(t, chartPath, "camunda-platform-test", "camunda-platform-webmodeler", []string{"templates/web-modeler/persistentvolumeclaim-restapi.yaml"}, []testhelpers.TestCase{testCase})
-}
-
 // TestDeploymentStrategyDefaultsToRollingUpdate asserts the default strategy
-// is RollingUpdate (preserves zero-downtime upgrade for users with RWX/
-// existingClaim setups). Users with chart-managed RWO PVCs hit a Multi-Attach
-// deadlock with RollingUpdate and must opt into "Recreate" — see
-// TestDeploymentStrategyRecreateOptIn.
+// is RollingUpdate. The restapi /tmp volume is a per-pod ephemeral volume, so
+// rollouts never contend for a shared RWO volume and zero-downtime RollingUpdate
+// is always safe.
 func TestDeploymentStrategyDefaultsToRollingUpdate(t *testing.T) {
 	t.Parallel()
 	chartPath, err := filepath.Abs("../../../")

charts/camunda-platform-8.8/templates/web-modeler/persistentvolumeclaim-restapi.yaml

@@ -4617,7 +4617,7 @@
                         },
                         "deploymentStrategy": {
                             "type": "string",
-                            "description": "update strategy for the restapi Deployment. Defaults to RollingUpdate (zero-downtime), which only works when the PVC supports concurrent attach (RWX storage, or accessModes including ReadWriteMany). For chart-managed PVCs on RWO storage, set to \"Recreate\" to avoid Multi-Attach deadlocks during helm upgrade (introduces brief downtime per upgrade).",
+                            "description": "update strategy for the restapi Deployment. Defaults to RollingUpdate, which is always safe because the default chart-managed persistence path uses a per-pod ephemeral volume (no concurrent-attach contention). Set to \"Recreate\" only when using existingClaim with a ReadWriteOnce volume that cannot tolerate concurrent attach during a rollout (introduces brief downtime per upgrade).",
                             "default": "RollingUpdate",
                             "enum": [
                                 "RollingUpdate",

charts/camunda-platform-8.8/test/unit/web-modeler/persistence_test.go

@@ -2141,7 +2141,7 @@ webModeler:
     annotations: {}
     ## @param webModeler.persistence.selector can be used to define a label selector for the persistent volume claim
     selector: {}
-    ## @param webModeler.persistence.deploymentStrategy update strategy for the restapi Deployment. Defaults to RollingUpdate (zero-downtime), which only works when the PVC supports concurrent attach (RWX storage, or accessModes including ReadWriteMany). For chart-managed PVCs on RWO storage, set to "Recreate" to avoid Multi-Attach deadlocks during helm upgrade (introduces brief downtime per upgrade).
+    ## @param webModeler.persistence.deploymentStrategy update strategy for the restapi Deployment. Defaults to RollingUpdate, which is always safe because the default chart-managed persistence path uses a per-pod ephemeral volume (no concurrent-attach contention). Set to "Recreate" only when using existingClaim with a ReadWriteOnce volume that cannot tolerate concurrent attach during a rollout (introduces brief downtime per upgrade).
     deploymentStrategy: RollingUpdate
 
   ## @extra webModeler.serviceAccount configuration for the service account the WebModeler pods are assigned to