From f8d2a1b797f72aadf4c137b4977a2e920f9d8923 Mon Sep 17 00:00:00 2001
From: Abdhesh Nayak <abdheshnayak@gmail.com>
Date: Mon, 7 Oct 2024 09:31:21 +0530
Subject: [PATCH] :sparkles: Added api for kubernetes resource health check

---
 apps/kube-health/.gitignore   |   2 +
 apps/kube-health/Dockerfile   |   5 ++
 apps/kube-health/Taskfile.yml |  35 ++++++++
 apps/kube-health/main.go      | 161 ++++++++++++++++++++++++++++++++++
 4 files changed, 203 insertions(+)
 create mode 100644 apps/kube-health/.gitignore
 create mode 100644 apps/kube-health/Dockerfile
 create mode 100644 apps/kube-health/Taskfile.yml
 create mode 100644 apps/kube-health/main.go

diff --git a/apps/kube-health/.gitignore b/apps/kube-health/.gitignore
new file mode 100644
index 000000000..e8ca7c86d
--- /dev/null
+++ b/apps/kube-health/.gitignore
@@ -0,0 +1,2 @@
+.secrets
+bin
diff --git a/apps/kube-health/Dockerfile b/apps/kube-health/Dockerfile
new file mode 100644
index 000000000..1f1bb07a0
--- /dev/null
+++ b/apps/kube-health/Dockerfile
@@ -0,0 +1,5 @@
+# syntax=docker/dockerfile:1
+FROM gcr.io/distroless/static-debian11:nonroot
+ARG BINARY TARGETARCH
+COPY --chown=1001 $BINARY-$TARGETARCH /kube-svc-health
+ENTRYPOINT ["/kube-svc-health"]
diff --git a/apps/kube-health/Taskfile.yml b/apps/kube-health/Taskfile.yml
new file mode 100644
index 000000000..aa61dd09b
--- /dev/null
+++ b/apps/kube-health/Taskfile.yml
@@ -0,0 +1,35 @@
+version: 3
+
+vars:
+  app: kube-svc-health
+  binary: "./bin/{{.app}}"
+
+tasks:
+  run:
+    dotenv:
+      - .secrets/env
+    cmds:
+      - go run ./main.go
+
+  build:
+    env:
+      output: "{{.binary}}-{{.GOARCH}}"
+      GOARCH: "{{.GOARCH}}"
+      CGO_ENABLED: 0
+    cmds:
+      - go build -o $output ./main.go
+
+  container:build-and-push:
+    requires:
+      vars:
+        - image
+    cmds:
+      - task: build
+        vars:
+          GOARCH: amd64
+
+      - task: build
+        vars:
+          GOARCH: arm64
+
+      - docker buildx build --platform linux/amd64,linux/arm64 --build-arg BINARY={{.binary}} -t {{.image}} . --push
diff --git a/apps/kube-health/main.go b/apps/kube-health/main.go
new file mode 100644
index 000000000..c415dd233
--- /dev/null
+++ b/apps/kube-health/main.go
@@ -0,0 +1,161 @@
+package main
+
+import (
+	"context"
+	"fmt"
+	"log"
+
+	"github.com/codingconcepts/env"
+	"github.com/gofiber/fiber/v2"
+	v1 "k8s.io/api/core/v1"
+	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
+	"k8s.io/client-go/kubernetes"
+	"k8s.io/client-go/rest"
+)
+
+type Env struct {
+	HttpPort           uint16 `env:"HTTP_PORT" default:"3000"`
+	KubernetesApiProxy string `env:"KUBERNETES_API_PROXY"`
+}
+
+func LoadEnv() (*Env, error) {
+	var e Env
+	if err := env.Set(&e); err != nil {
+		return nil, err
+	}
+	return &e, nil
+}
+
+func main() {
+	if err := Run(); err != nil {
+		panic(err)
+	}
+}
+
+func Run() error {
+	env, err := LoadEnv()
+	if err != nil {
+		return err
+	}
+
+	kubeconfig := &rest.Config{
+		Host: env.KubernetesApiProxy,
+	}
+
+	if env.KubernetesApiProxy == "" {
+		var err error
+		kubeconfig, err = rest.InClusterConfig()
+		if err != nil {
+			return err
+		}
+	}
+
+	// Create the Kubernetes client
+	clientset, err := kubernetes.NewForConfig(kubeconfig)
+	if err != nil {
+		return err
+	}
+
+	app := fiber.New()
+
+	app.Get("/_healthy", func(c *fiber.Ctx) error {
+		return c.Status(200).JSON(fiber.Map{
+			"status": "healthy",
+		})
+	})
+
+	app.Get("/kubernetes", func(c *fiber.Ctx) error {
+		b, err := clientset.Discovery().RESTClient().Get().AbsPath("/healthz").DoRaw(context.TODO())
+		if err != nil {
+			return err
+		}
+
+		return c.Status(200).Send(b)
+	})
+
+	app.Get("/:ns/:svc", func(c *fiber.Ctx) error {
+		ns := c.Params("ns")
+		svc := c.Params("svc")
+
+		pods, unhealthy, err := checkSvcHealth(clientset, ns, svc)
+		if err != nil {
+			return err
+		}
+
+		healthy := pods - unhealthy
+
+		if healthy == 0 {
+			return c.Status(500).JSON(fiber.Map{
+				"status":  "unhealthy",
+				"running": fmt.Sprintf("%d/%d", healthy, pods),
+			})
+		}
+
+		return c.Status(200).JSON(fiber.Map{
+			"status":  "healthy",
+			"running": fmt.Sprintf("%d/%d", healthy, pods),
+		})
+	})
+
+	app.All("/*", func(c *fiber.Ctx) error {
+		return c.Status(404).JSON(fiber.Map{
+			"status": "not found",
+		})
+	})
+
+	if err := app.Listen(fmt.Sprintf(":%d", env.HttpPort)); err != nil {
+		return err
+	}
+
+	return nil
+}
+
+func checkSvcHealth(clientset *kubernetes.Clientset, ns, svcName string) (int, int, error) {
+
+	if svcName == "" {
+		return 0, 0, fmt.Errorf("Service name must be provided")
+	}
+	if ns == "" {
+		return 0, 0, fmt.Errorf("Namespace must be provided")
+	}
+
+	// Get the service
+	svc, err := clientset.CoreV1().Services(ns).Get(context.TODO(), svcName, metav1.GetOptions{})
+	if err != nil {
+		return 0, 0, err
+	}
+
+	// List the pods using the service selector
+	labelSelector := metav1.FormatLabelSelector(&metav1.LabelSelector{MatchLabels: svc.Spec.Selector})
+	pods, err := clientset.CoreV1().Pods(ns).List(context.TODO(), metav1.ListOptions{LabelSelector: labelSelector})
+	if err != nil {
+		return 0, 0, err
+	}
+
+	count := 0
+	// Check the status of each pod
+	for _, pod := range pods.Items {
+		if err := checkPodHealth(&pod); err != nil {
+			log.Printf("Error: %v", err)
+			count++
+		}
+	}
+
+	return len(pods.Items), count, nil
+}
+
+func checkPodHealth(pod *v1.Pod) error {
+	ready := false
+	for _, condition := range pod.Status.Conditions {
+		if condition.Type == v1.PodReady && condition.Status == v1.ConditionTrue {
+			ready = true
+			break
+		}
+	}
+
+	if !ready {
+		return fmt.Errorf("Pod %s is not healthy", pod.Name)
+	}
+
+	return nil
+}