ci: mtu check for cilium e2e (#3624)

* init commit: create script for mtu check

* ci: cilium e2e run mtu check

* ci: scale pod deployment in release tests

* ci: rollout status

* test: template call

* addressing comments, fix script scale deployment

* address nits, test maxSkew, add exit on errors

* adding missing template calls

* fix cilium-overlay e2e

Author: camrynl

.pipelines/cni/cilium/cilium-overlay-load-test-template.yaml

@@ -266,6 +266,7 @@ stages:
               fi
             name: "testAsyncDelete"
             displayName: "Verify Async Delete when CNS is down"
+          - template: ../../templates/cilium-mtu-check.yaml
       - template: ../k8s-e2e/k8s-e2e-job-template.yaml
         parameters:
           sub: $(BUILD_VALIDATIONS_SERVICE_CONNECTION)

.pipelines/singletenancy/cilium-dualstack-overlay/cilium-dualstackoverlay-e2e-step-template.yaml

@@ -158,3 +158,5 @@ steps:
       fi
     name: "testAsyncDelete"
     displayName: "Verify Async Delete when CNS is down"
+  
+  - template: ../../templates/cilium-mtu-check.yaml

.pipelines/singletenancy/cilium-dualstack-overlay/cilium-dualstackoverlay-e2e.steps.yaml

@@ -170,3 +170,5 @@ steps:
       fi
     name: "testAsyncDelete"
     displayName: "Verify Async Delete when CNS is down"
+  
+  - template: ../../templates/cilium-mtu-check.yaml

.pipelines/singletenancy/cilium-overlay-withhubble/cilium-overlay-e2e-step-template.yaml

@@ -196,6 +196,8 @@ steps:
     name: "testAsyncDelete"
     displayName: "Verify Async Delete when CNS is down"
 
+  - template: ../../templates/cilium-mtu-check.yaml
+
   - script: |
       ARTIFACT_DIR=$(Build.ArtifactStagingDirectory)/test-output/
       echo $ARTIFACT_DIR

.pipelines/singletenancy/cilium-overlay-withhubble/cilium-overlay-e2e.steps.yaml

@@ -198,6 +198,8 @@ steps:
       fi
     name: "testAsyncDelete"
     displayName: "Verify Async Delete when CNS is down"
+  
+  - template: ../../templates/cilium-mtu-check.yaml
 
   - script: |
       ARTIFACT_DIR=$(Build.ArtifactStagingDirectory)/test-output/

.pipelines/singletenancy/cilium-overlay/cilium-overlay-e2e-step-template.yaml

@@ -237,3 +237,5 @@ steps:
       fi
     name: "testAsyncDelete"
     displayName: "Verify Async Delete when CNS is down"
+
+  - template: ../../templates/cilium-mtu-check.yaml

.pipelines/singletenancy/cilium-overlay/cilium-overlay-e2e.steps.yaml

@@ -248,3 +248,7 @@ steps:
       fi
     name: "testAsyncDelete"
     displayName: "Verify Async Delete when CNS is down"
+  
+  - template: ../../templates/cilium-mtu-check.yaml
+  
+

.pipelines/templates/cilium-mtu-check.yaml

@@ -0,0 +1,7 @@
+steps:
+  - script: |
+      cd hack/scripts
+      chmod +x cilium-mtu-validation.sh
+      ./cilium-mtu-validation.sh
+    name: "CiliumMTUValidation"
+    displayName: "Run Cilium MTU Validation"

.pipelines/templates/cilium-tests.yaml

@@ -81,3 +81,5 @@ steps:
       fi
     name: "testAsyncDelete"
     displayName: "Verify Async Delete when CNS is down"
+  
+  - template: ./cilium-mtu-check.yaml

hack/manifests/nginx.yaml

@@ -0,0 +1,29 @@
+apiVersion: apps/v1
+kind: Deployment
+metadata:
+  name: nginx
+  labels:
+    app: nginx
+  namespace: kube-system
+spec:
+  replicas: 4
+  selector:
+    matchLabels:
+      app: nginx
+  template:
+    metadata:
+      labels:
+        app: nginx
+    spec:
+      containers:
+      - name: nginx
+        image: mcr.microsoft.com/azurelinux/base/nginx:1
+        ports:
+          - containerPort: 80
+      topologySpreadConstraints:
+      - maxSkew: 1
+        topologyKey: kubernetes.io/hostname # KV: Key is hostname, value is each unique nodename
+        whenUnsatisfiable: ScheduleAnyway
+        labelSelector:
+          matchLabels:
+            app: nginx