create example for issues spring-projects/spring-boot#26627

README.md

@@ -1 +1,17 @@
-# Spring Boot Prometheus Bug
+# Spring Boot Bug
+
+Refers to issue: https://github.com/spring-projects/spring-boot/issues/26627
+
+How to run it:
+- Make sure to have kind installed and create the cluster using kind-with-registry.sh
+- Build the docker image with `./gradlew jibDockerBuild`
+- Run the following docker commands to make the image available in the cluster
+  - `docker tag spring-boot-bug:2.4.6 localhost:5000/spring-boot-bug:2.4.6`
+  - `docker push localhost:5000/spring-boot-bug:2.4.6`
+- Apply the k8s resources with:
+  - `kubectl -f apply kubernetes/configmap`
+  - `kubectl -f apply kubernetes/deployment`
+
+To build the image for a different version of spring-boot:
+- Change the `version` in the `build.gradle.kts` file
+- Change the `image` tag in the `kubernetes/deployment.yaml` file

build.gradle.kts

@@ -1,16 +1,19 @@
 import org.jetbrains.kotlin.gradle.tasks.KotlinCompile
 
 plugins {
-    kotlin("jvm") version "1.4.10"
-    id("org.jetbrains.kotlin.plugin.spring") version "1.4.10"
+    kotlin("jvm") version "1.4.32"
+    id("org.jetbrains.kotlin.plugin.spring") version "1.4.32"
+    id("com.google.cloud.tools.jib") version "3.0.0"
 }
 
 repositories {
     mavenCentral()
 }
 
+version = "2.4.6"
+
 dependencies {
-    implementation(platform("org.springframework.boot:spring-boot-dependencies:2.4.0"))
+    implementation(platform("org.springframework.boot:spring-boot-dependencies:$version"))
 
     implementation("io.micrometer:micrometer-registry-prometheus")
     implementation("org.springframework.boot:spring-boot-starter-actuator")

kind-with-registry.sh

@@ -0,0 +1,41 @@
+#!/bin/sh
+set -o errexit
+
+# create registry container unless it already exists
+reg_name='kind-registry'
+reg_port='5000'
+running="$(docker inspect -f '{{.State.Running}}' "${reg_name}" 2>/dev/null || true)"
+if [ "${running}" != 'true' ]; then
+  docker run \
+    -d --restart=always -p "127.0.0.1:${reg_port}:5000" --name "${reg_name}" \
+    registry:2
+fi
+
+# create a cluster with the local registry enabled in containerd
+cat <<EOF | kind create cluster --config=-
+kind: Cluster
+apiVersion: kind.x-k8s.io/v1alpha4
+containerdConfigPatches:
+- |-
+  [plugins."io.containerd.grpc.v1.cri".registry.mirrors."localhost:${reg_port}"]
+    endpoint = ["http://${reg_name}:${reg_port}"]
+EOF
+
+# connect the registry to the cluster network
+# (the network may already be connected)
+docker network connect "kind" "${reg_name}" || true
+
+# Document the local registry
+# https://github.com/kubernetes/enhancements/tree/master/keps/sig-cluster-lifecycle/generic/1755-communicating-a-local-registry
+cat <<EOF | kubectl apply -f -
+apiVersion: v1
+kind: ConfigMap
+metadata:
+  name: local-registry-hosting
+  namespace: kube-public
+data:
+  localRegistryHosting.v1: |
+    host: "localhost:${reg_port}"
+    help: "https://kind.sigs.k8s.io/docs/user/local-registry/"
+EOF
+

kubernetes/configmap.yaml

@@ -0,0 +1,9 @@
+apiVersion: v1
+kind: ConfigMap
+metadata:
+  name: spring-boot-application
+  labels:
+    app: spring-boot-application
+data:
+  application-kubernetes.yml: |
+    server.port: 8080

kubernetes/deployment.yaml

@@ -0,0 +1,74 @@
+apiVersion: apps/v1
+kind: Deployment
+metadata:
+  name: spring-boot-application
+  labels:
+    app: spring-boot-application
+spec:
+  strategy:
+    rollingUpdate:
+      maxSurge: 1
+      maxUnavailable: 0
+    type: RollingUpdate
+  replicas: 1
+  selector:
+    matchLabels:
+      app: spring-boot-application
+  template:
+    metadata:
+      labels:
+        app: spring-boot-application
+    spec:
+      securityContext:
+        runAsNonRoot: true
+        runAsUser: 65534
+        runAsGroup: 65534
+        # needed because of https://github.com/aws/amazon-eks-pod-identity-webhook/issues/8
+        fsGroup: 65534
+      containers:
+        - name: spring-boot-application
+          image: "localhost:5000/spring-boot-bug:2.4.6"
+          imagePullPolicy: Always
+          env:
+            - name: JAVA_TOOL_OPTIONS
+              value: "-XX:+UseContainerSupport -XX:InitialRAMPercentage=50 -XX:MaxRAMPercentage=80"
+            - name: SPRING_PROFILES_ACTIVE
+              value: "kubernetes"
+          ports:
+            - containerPort: 8080
+              name: http
+              protocol: TCP
+          livenessProbe:
+            failureThreshold: 5
+            httpGet:
+              path: /actuator/health/liveness
+              port: http
+            initialDelaySeconds: 10
+            periodSeconds: 3
+            successThreshold: 1
+            timeoutSeconds: 5
+          readinessProbe:
+            failureThreshold: 5
+            httpGet:
+              path: /actuator/health/readiness
+              port: http
+            initialDelaySeconds: 10
+            periodSeconds: 3
+            successThreshold: 1
+            timeoutSeconds: 5
+          volumeMounts:
+            - name: tmp
+              mountPath: /tmp
+            - name: spring-boot-application
+              mountPath: /config
+              readOnly: true
+          securityContext:
+            privileged: false
+            readOnlyRootFilesystem: true
+      restartPolicy: Always
+      volumes:
+        - name: tmp
+          emptyDir: { }
+        - name: spring-boot-application
+          configMap:
+            name: spring-boot-application