Add healthcheck endpoints and scripts

Author: sidpalas

05-example-web-application/api-golang/healthcheck/healthcheck.go

@@ -0,0 +1,36 @@
+package main
+
+import (
+	"fmt"
+	"log"
+	"net/http"
+	"os"
+	"time"
+)
+
+func main() {
+
+	port, exists := os.LookupEnv("PORT")
+	if !exists {
+		port = "8080"
+	}
+
+	client := http.Client{
+		Timeout: 2 * time.Second,
+	}
+
+	resp, err := client.Get("http://localhost:" + port + "/ping")
+	if err != nil {
+		log.Fatal(err)
+	}
+
+	// Print the HTTP Status Code and Status Name
+	fmt.Println("HTTP Response Status:", resp.StatusCode, http.StatusText(resp.StatusCode))
+
+	if resp.StatusCode >= 200 && resp.StatusCode <= 299 {
+		fmt.Println("HTTP Status is in the 2xx range")
+	} else {
+		fmt.Println("Argh! Broken")
+		os.Exit(1)
+	}
+}

05-example-web-application/api-golang/main.go

@@ -42,5 +42,11 @@ func main() {
 			"now": tm,
 		})
 	})
-	r.Run() // listen and serve on 0.0.0.0:8080
+
+	r.GET("/ping", func(c *gin.Context) {
+		tm = database.GetTime(c)
+		c.JSON(200, "pong")
+	})
+
+	r.Run() // listen and serve on 0.0.0.0:8080 (or "PORT" env var)
 }

05-example-web-application/api-node/healthcheck/healthcheck.js

@@ -0,0 +1,21 @@
+var http = require('http');
+
+var options = {
+  timeout: 2000,
+  host: 'localhost',
+  port: process.env.PORT || 3000,
+  path: '/ping',
+};
+
+var request = http.request(options, (res) => {
+  console.info('STATUS: ' + res.statusCode);
+  process.exitCode = res.statusCode === 200 ? 0 : 1;
+  process.exit();
+});
+
+request.on('error', function (err) {
+  console.error('ERROR', err);
+  process.exit(1);
+});
+
+request.end();

05-example-web-application/api-node/src/index.js

@@ -4,7 +4,7 @@ const express = require('express');
 const morgan = require('morgan');
 
 const app = express();
-const port = 3000;
+const port = process.env.PORT || 3000;
 
 // setup the logger
 app.use(morgan('tiny'));
@@ -16,6 +16,10 @@ app.get('/', async (req, res) => {
   res.send(response);
 });
 
+app.get('/ping', async (_, res) => {
+  res.send('pong');
+});
+
 const server = app.listen(port, () => {
   console.log(`Example app listening on port ${port}`);
 });

05-example-web-application/client-react/nginx.conf

@@ -1,5 +1,10 @@
 server {
   listen 80;
+  location /ping {
+        access_log off;
+        add_header 'Content-Type' 'text/plain';
+        return 200 "pong";
+  }
   location /api/golang/ {
         resolver 127.0.0.1;
         proxy_set_header X-Forwarded-Host $host;

06-building-container-images/api-golang/Dockerfile.7

@@ -0,0 +1,58 @@
+# Pin specific version for stability
+# Use separate stage for building image
+# Use debian for easier build utilities
+FROM golang:1.19-bullseye AS build
+
+# Add non root user
+RUN useradd -u 1001 nonroot
+
+WORKDIR /app 
+
+# Copy only files required to install dependencies (better layer caching)
+COPY go.mod go.sum ./
+
+# Use cache mount to speed up install of existing dependencies
+RUN --mount=type=cache,target=/go/pkg/mod \
+  --mount=type=cache,target=/root/.cache/go-build \
+  go mod download
+
+COPY . .
+
+# Compile healthcheck
+RUN go build \
+  -ldflags="-linkmode external -extldflags -static" \
+  -tags netgo \
+  -o healthcheck \
+  ./healthcheck/healthcheck.go
+
+# Compile application during build rather than at runtime
+# Add flags to statically link binary
+RUN go build \
+  -ldflags="-linkmode external -extldflags -static" \
+  -tags netgo \
+  -o api-golang
+
+# Use separate stage for deployable image
+FROM scratch
+
+# Set gin mode
+ENV GIN_MODE=release
+
+WORKDIR /
+
+# Copy the passwd file
+COPY --from=build /etc/passwd /etc/passwd
+
+# Copy the healthcheck binary from the build stage
+COPY --from=build /app/healthcheck/healthcheck healthcheck
+
+# Copy the app binary from the build stage
+COPY --from=build /app/api-golang api-golang
+
+# Use nonroot user
+USER nonroot
+
+# Indicate expected port
+EXPOSE 8080
+
+CMD ["/api-golang"]

06-building-container-images/api-golang/Makefile

@@ -11,7 +11,7 @@ build-N:
 
 .PHONY: build-all
 build-all:
-	for number in 0 1 2 3 4 5 6 ; do \
+	for number in 0 1 2 3 4 5 6 7; do \
 			N=$$number $(MAKE) build-N; \
 	done
 
@@ -21,6 +21,6 @@ push-N:
 
 .PHONY: push-all
 push-all:
-	for number in 0 1 2 3 4 5 6 ; do \
+	for number in 0 1 2 3 4 5 6 7; do \
 			N=$$number $(MAKE) push-N; \
 	done

06-building-container-images/api-node/Dockerfile.8

@@ -0,0 +1,39 @@
+# Pin specific version for stability
+# Use alpine for reduced image size
+FROM node:19.4-alpine
+
+# Set NODE_ENV
+ENV NODE_ENV production
+
+# Specify working directory other than /
+WORKDIR /usr/src/app
+
+# Copy only files required to install
+# dependencies (better layer caching)
+COPY package*.json ./
+
+# Install only production dependencies
+# Use cache mount to speed up install of existing dependencies
+RUN --mount=type=cache,target=/usr/src/app/.npm \
+  npm set cache /usr/src/app/.npm && \
+  npm ci --only=production
+
+# Use non-root user
+# Use --chown on COPY commands to set file permissions
+USER node
+
+# Copy the healthcheck script
+COPY --chown=node:node ./healthcheck/ .
+
+# Copy remaining source code AFTER installing dependencies. 
+# Again, copy only the necessary files
+COPY --chown=node:node ./src/ .
+
+# Indicate expected port
+EXPOSE 3000
+
+CMD [ "node", "index.js" ]
+
+# TODO: Use multi-stage with distroless image or chainguard image? 
+# https://github.com/GoogleContainerTools/distroless/blob/main/examples/nodejs/Dockerfile
+# https://edu.chainguard.dev/chainguard/chainguard-images/reference/node/overview/

06-building-container-images/api-node/Makefile

@@ -11,7 +11,7 @@ build-N:
 
 .PHONY: build-all
 build-all:
-	for number in 0 1 2 3 4 5 6 7 ; do \
+	for number in 0 1 2 3 4 5 6 7 8; do \
 			N=$$number $(MAKE) build-N; \
 	done
 
@@ -21,6 +21,6 @@ push-N:
 
 .PHONY: push-all
 push-all:
-	for number in 0 1 2 3 4 5 6 7; do \
+	for number in 0 1 2 3 4 5 6 7 8; do \
 			N=$$number $(MAKE) push-N; \
 	done

08-running-containers/docker-compose.yml

@@ -10,7 +10,7 @@ services:
   api-node:
     build:
       context: ../05-example-web-application/api-node/
-      dockerfile: ../../06-building-container-images/api-node/Dockerfile.7
+      dockerfile: ../../06-building-container-images/api-node/Dockerfile.8
     init: true
     depends_on:
       - db