Simple API

A simple REST API application with Redis database built with Spring boot to learn Docker and Kubernetes

Learning topics:

Spring boot Rest API
Springboot Scheduler
REST API HTTP status codes
Microservices architecture
Microservices communication
Microservices caching system
Application logging
Application scaling
Application Health check

Docker

Docker services
Docker Networks
Docker volumes
Docker Container communication
Docker Container Healthcheck
Docker Image build
Docker Rootless Container

Kubernetes

Kubernetes Pods
Kubernetes Deployments
Kubernetes services
Kubernetes ConfigMap
Kubernetes Volumes
Kubernetes Rootless Pods
Kubernetes Ingress

Links:

API Doc

/ GET

Response:

{
	"success": true,
	"code": 200,
	"message": "OK",
	"error": null,
	"data": "Hello from Simple API, everything is ok"
}

/books GET

Get all books

{
	"success": true,
	"code": 200,
	"message": "OK",
	"error": null,
	"data": [
      {
        "title": "The Kubernetes Bible",
        "author": "Nassim Kebbani, Piotr Tylenda",
        "country": "USA",
        "imageLink": "images/things-fall-apart.jpg",
        "language": "English",
        "link": "https://en.wikipedia.org/wiki/Things_Fall_Apart\n",
        "pages": 652,
        "year": 2022, 
        "createdAt": "2024-04-20 10:34",
        "updatedAt": "2024-04-20 10:34"
  }, 
  {
    "title": "Kubernetes - An Enterprise Guide",
    "author": "Marc Boorshtein, Scott Surovich",
    "country": "USA",
    "imageLink": "images/things-fall-apart.jpg",
    "language": "English",
    "link": "https://en.wikipedia.org/wiki/Things_Fall_Apart\n",
    "pages": 652,
    "year": 2022,
    "createdAt": "2024-04-20 10:34",
    "updatedAt": "2024-04-20 10:34"
  },  
  {
    "title": "System Design Interview Vol1",
    "author": "Alex U & Sahn Lam",
    "country": "USA",
    "imageLink": "images/things-fall-apart.jpg",
    "language": "English",
    "link": "https://en.wikipedia.org/wiki/Things_Fall_Apart\n",
    "pages": 652,
    "year": 2022,
    "createdAt": "2024-04-20 10:34",
    "updatedAt": "2024-04-20 10:34"
  },  
  {
     "title": "System Design Interview Vol2",
    "author": "Alex U & Sahn Lam",
    "country": "USA",
    "imageLink": "images/things-fall-apart.jpg",
    "language": "English",
    "link": "https://en.wikipedia.org/wiki/Things_Fall_Apart\n",
    "pages": 652,
    "year": 2022,
    "createdAt": "2024-04-20 10:34",
    "updatedAt": "2024-04-20 10:34"
  }
	]
}

/books POST

Create a new book

{
      "title": "The Kubernetes Bible",
      "author": "Nassim Kebbani, Piotr Tylenda",
      "country": "USA",
      "imageLink": "images/things-fall-apart.jpg",
      "language": "English",
      "link": "https://en.wikipedia.org/wiki/Things_Fall_Apart\n",
      "pages": 652,
      "year": 2022
	
}

/books/{id} PUT

Update aBook

{
      "title": "The Kubernetes Bible",
      "author": "Nassim Kebbani, Piotr Tylenda",
      "country": "USA",
      "imageLink": "images/things-fall-apart.jpg",
      "language": "English",
      "link": "https://en.wikipedia.org/wiki/Things_Fall_Apart\n",
      "pages": 652,
      "year": 2022
	
}

/books/{id} GET

Get book by Id

{
	"success": true,
	"code": 200,
	"message": "OK",
	"error": null,
	"data": {
      "title": "The Kubernetes Bible",
      "author": "Nassim Kebbani, Piotr Tylenda",
      "country": "USA",
      "imageLink": "images/things-fall-apart.jpg",
      "language": "English",
      "link": "https://en.wikipedia.org/wiki/Things_Fall_Apart\n",
      "pages": 652,
      "year": 2022
	}
}

/books/{id} DELETE

Delete book by Id

/deleteAll DELETE

Delete all books

Restart the application and if Database seed (RUN_DATA_SEED= true) is enabled, the predefined data will be restored

/version GET

Get API Version

Run on Docker

Download Docker Desktop (https://www.docker.com/products/)

Create Network

docker network create web

Deploy Simple APi

Create compose.yaml file and paste the content below

version: '3.9'
services:
  simple-api:
    container_name: simple-api
    image: jkaninda/simple-api:latest
    restart: unless-stopped
    ports:
      - "8080:8080"
    networks:
      - web
networks:
  web:
    external: true
    name: web

docker compose up -d

Advanced Docker deployment

Let's apply some configurations to our simple-api service and deploy the redis database, so that we can interact with the API

simple-api and redis must be connected to the same network, so they can communicate with each other

Create compose.yaml file and paste the content below

version: '3.9'
services:
  simple-api:
    container_name: simple-api
    image: jkaninda/simple-api:latest
    restart: unless-stopped
    environment:
      - SPRING_DATA_REDIS_HOST=redis
      - SPRING_DATA_REDIS_PORT=6379
      - SPRING_DATA_REDIS_TIMEOUT=60000
      - SPRING_DATA_REDIS_PASSWORD=password
      ## Insert Redis fake data, requires Redis data source || By default is disabled
      - RUN_DATA_SEED= true
    ports:
      - "8080:8080"
    networks:
      - web
  redis:
    image: redis:alpine
    container_name: redis
    restart: unless-stopped
    command: redis-server --appendonly yes --requirepass password
    expose:
      - 6379
    volumes:
      - ./redis:/data
    networks:
      - web
networks:
  web:
    external: true
    name: web

docker compose up -d

Environment variable from a file

Create simple-api.env file and paste the content below

SPRING_DATA_REDIS_HOST=redis
SPRING_DATA_REDIS_PORT=6379
SPRING_DATA_REDIS_TIMEOUT=60000
SPRING_DATA_REDIS_PASSWORD=password
##Insert Redis fake data, requires Redis data source || By default is disabled
RUN_DATA_SEED=true

Let's update our compose.yaml file

version: '3.9'
services:
  simple-api:
    container_name: simple-api
    image: jkaninda/simple-api:latest
    restart: unless-stopped
    env_file:
      - simple-api.env
    ports:
      - "8080:8080"
    networks:
      - web
  redis:
    image: redis:alpine
    container_name: redis
    restart: unless-stopped
    command: redis-server --appendonly yes --requirepass "${SPRING_DATA_REDIS_PASSWORD}"
    env_file:
      - simple-api.env
    expose:
      - 6379
    volumes:
      - ./redis:/data
    networks:
      - web
networks:
  web:
    external: true
    name: web

Docker container with Health check

version: '3.9'
services:
  simple-api:
    container_name: simple-api
    image: jkaninda/simple-api:latest
    restart: unless-stopped
    env_file:
      - simple-api.env
    ports:
      - "8080:8080"
    ## Application Health check
    healthcheck:
      test: wget --no-verbose --tries=1 --spider http://localhost:8080/internal/health/live || exit 1
    networks:
      - web
  redis:
    image: redis:alpine
    container_name: redis
    restart: unless-stopped
    command: redis-server --appendonly yes --requirepass "${SPRING_DATA_REDIS_PASSWORD}"
    env_file:
      - simple-api.env
    expose:
      - 6379
    volumes:
      - ./redis:/data
    networks:
      - web
networks:
  web:
    external: true
    name: web

Build Docker image

Dockerfile

# Buil Stage
FROM maven:3.8.7-amazoncorretto-17 AS MAVEN_TOOL_CHAIN
WORKDIR /tmp/
COPY pom.xml /tmp/pom.xml
COPY src /tmp/src/
RUN mvn clean package -B

FROM amazoncorretto:17-alpine3.19-jdk
ENV VERSION="1.0"
LABEL author="Jonas Kaninda"
LABEL github="https://github.com/jkaninda/simple-api"
ARG JAR_FILE=target/*.jar
# Copy from build stage
COPY --from=MAVEN_TOOL_CHAIN /tmp/$JAR_FILE /App/api.jar
COPY ./data /data
EXPOSE 8080
ENTRYPOINT ["java", "-jar", "/App/api.jar"]

docker build -f docker/Dockerfile -t jkaninda/simple-api:latest .

Screenshots

Docker

Insomnia

Interact with the API

To test our API we need an api client, let's download insomnia

Download Insomnia (https://insomnia.rest/) for your platform

RUN on Kubernetes

Create a Kubernetes cluster on Docker using Kind

Install kind (https://kind.sigs.k8s.io/docs/user/quick-start/)

On macOS via Homebrew:

brew install kind

On Windows via Chocolatey (https://chocolatey.org/packages/kind)

choco install kind

Create cluster

cat <<EOF | kind create cluster --config=-
kind: Cluster
apiVersion: kind.x-k8s.io/v1alpha4
nodes:
- role: control-plane
  kubeadmConfigPatches:
  - |
    kind: InitConfiguration
    nodeRegistration:
      kubeletExtraArgs:
        node-labels: "ingress-ready=true"
  extraPortMappings:
  - containerPort: 80
    hostPort: 80
    protocol: TCP
  - containerPort: 443
    hostPort: 443
    protocol: TCP
EOF

Deploy Simple API

Create Kubernetes Namespace

kubectl create namespace simple-api

Deploy Simple APi

cat <<EOF | kubectl apply -f -
apiVersion: apps/v1
kind: Deployment
metadata:
  name: simple-api
  namespace: simple-api
spec:
  replicas: 1
  selector:
    matchLabels:
      app: simple-api
  template:
    metadata:
      labels:
        app: simple-api
    spec:
      containers:
      - name: simple-api
        image: jkaninda/simple-api:latest
        resources:
          limits:
            memory: "750Mi"
            cpu: "500m"
        ports:
        - containerPort: 8080
EOF

kubectl  -n simple-api get pods

Create Simple API Service

cat <<EOF | kubectl apply -f -
apiVersion: v1
kind: Service
metadata:
  name: simple-api-svc
  namespace: simple-api
spec:
  selector:
    app: simple-api
  ports:
  - port: 8080
    targetPort: 8080
EOF

kubectl -n simple-api get svc
NAME             TYPE        CLUSTER-IP     EXTERNAL-IP   PORT(S)    AGE
simple-api-svc   ClusterIP   10.96.127.66   <none>        8080/TCP   42s

Deploy All

cat <<EOF | kubectl apply -f -
apiVersion: v1
kind: Namespace
metadata:
    name: simple-api
---
apiVersion: v1
kind: ConfigMap
metadata:
  name: simple-api
  namespace: simple-api
data:
  SPRING_DATA_REDIS_HOST: 'redis-svc'
  SPRING_DATA_REDIS_PORT: '6379'
  SPRING_DATA_REDIS_PASSWORD: 'password'
  ## Insert Redis fake data, requires Redis data source || By default is disabled
  RUN_DATA_SEED: 'true'
---
apiVersion: apps/v1
kind: Deployment
metadata:
  name: simple-api
  namespace: simple-api
spec:
  replicas: 1
  selector:
    matchLabels:
      app: simple-api
  template:
    metadata:
      labels:
        app: simple-api
    spec:
      containers:
      - name: simple-api
        image: jkaninda/simple-api:latest
        envFrom:
         - configMapRef:
                name: simple-api
        resources:
          limits:
            memory: "750Mi"
            cpu: "500m"
        ports:
        - containerPort: 8080
---
apiVersion: apps/v1
kind: Deployment
metadata:
  name: redis
  namespace: simple-api
spec:
  selector:
    matchLabels:
      app: redis
  template:
    metadata:
      labels:
        app: redis
    spec:
      containers:
      - name: redis
        image: redis:alpine
        command:
          - redis-server
          - --appendonly yes 
          - --requirepass "password"
        resources:
          limits:
            memory: "128Mi"
            cpu: "500m"
        ports:
        - containerPort: 6379
        volumeMounts:
         - mountPath: /data
           name: data
      volumes:
        - name: data
          emptyDir: {}
---
apiVersion: v1
kind: Service
metadata:
  name: redis-svc
  namespace: simple-api
spec:
  selector:
    app: redis
  ports:
  - port: 6379
    targetPort: 6379
---
apiVersion: v1
kind: Service
metadata:
  name: simple-api-svc
  namespace: simple-api
spec:
  selector:
    app: simple-api
  ports:
  - port: 8080
    targetPort: 8080
EOF

Or create deployment.yaml file and paste the content below

apiVersion: v1
kind: Namespace
metadata:
    name: simple-api
---
apiVersion: v1
kind: ConfigMap
metadata:
  name: simple-api
  namespace: simple-api
data:
  SPRING_DATA_REDIS_HOST: 'redis-svc'
  SPRING_DATA_REDIS_PORT: '6379'
  SPRING_DATA_REDIS_PASSWORD: 'password'
  ## Insert Redis fake data, requires Redis data source || By default is disabled
  RUN_DATA_SEED: 'true'
---
apiVersion: apps/v1
kind: Deployment
metadata:
  name: simple-api
  namespace: simple-api
spec:
  replicas: 1
  selector:
    matchLabels:
      app: simple-api
  template:
    metadata:
      labels:
        app: simple-api
    spec:
      containers:
      - name: simple-api
        image: jkaninda/simple-api:latest
        envFrom:
         - configMapRef:
                name: simple-api
        resources:
          limits:
            memory: "750Mi"
            cpu: "500m"
        ports:
        - containerPort: 8080
---
apiVersion: apps/v1
kind: Deployment
metadata:
  name: redis
  namespace: simple-api
spec:
  selector:
    matchLabels:
      app: redis
  template:
    metadata:
      labels:
        app: redis
    spec:
      containers:
      - name: redis
        image: redis:alpine
        command:
          - redis-server
          - --appendonly yes 
          - --requirepass "password"
        resources:
          limits:
            memory: "128Mi"
            cpu: "500m"
        ports:
        - containerPort: 6379
        volumeMounts:
         - mountPath: /data
           name: data
      volumes:
        - name: data
          emptyDir: {}
---
apiVersion: v1
kind: Service
metadata:
  name: redis-svc
  namespace: simple-api
spec:
  selector:
    app: redis
  ports:
  - port: 6379
    targetPort: 6379
---
apiVersion: v1
kind: Service
metadata:
  name: simple-api-svc
  namespace: simple-api
spec:
  selector:
    app: simple-api
  ports:
  - port: 8080
    targetPort: 8080
---

Deploy

kubectl apply -f deployment.yaml

Get all resources in the simple-api namespace

kubectl -n simple-api get all
NAME                              READY   STATUS    RESTARTS   AGE
pod/redis-6c8787c7d4-2txqr        1/1     Running   0          37s
pod/simple-api-7fcd9cf54f-rp47w   1/1     Running   0          37s

NAME                     TYPE        CLUSTER-IP    EXTERNAL-IP   PORT(S)    AGE
service/redis-svc        ClusterIP   10.96.251.1   <none>        6379/TCP   37s
service/simple-api-svc   ClusterIP   10.96.79.12   <none>        8080/TCP   37s

NAME                         READY   UP-TO-DATE   AVAILABLE   AGE
deployment.apps/redis        1/1     1            1           38s
deployment.apps/simple-api   1/1     1            1           38s

NAME                                    DESIRED   CURRENT   READY   AGE
replicaset.apps/redis-6c8787c7d4        1         1         1       37s
replicaset.apps/simple-api-7fcd9cf54f   1         1         1       38s

Get pods

kubectl -n simple-api get po
NAME                          READY   STATUS    RESTARTS   AGE
redis-5868d6f857-8kdjj        1/1     Running   0          32m
simple-api-7fcd9cf54f-lgwnp   1/1     Running   0          30m

Kubernetes deployment port forward

kubectl -n simple-api port-forward deployment/simple-api 8080:8080

Log

To see the application's logs

kubectl -n simple-api  logs simple-api-7fcd9cf54f-lgwnp

simple-api-7fcd9cf54f-lgwnp is the name of the pod, you cane replace it by the name of your pod

Scalability

Scalability is the property of a system to handle a growing amount of work.

In our case we want to scale our application as the requests growing

Scale API

kubectl -n simple-api scale deployment/simple-api --replicas 2

Ingress

apiVersion: networking.k8s.io/v1
kind: Ingress
metadata:
  name: simple-api-ingress
  labels:
    name: simple-api
    namespace: simple-api
spec:
  rules:
  ## replace by your hostname
  - host: simple-api.localhost
    http:
      paths:
      - pathType: Prefix
        path: "/"
        backend:
          service:
            name: simple-api-svc
            port: 
              number: 8080

Run as Non-root

To run the pod as non-root user, you can change the image tag by adding rootless

cat <<EOF | kubectl apply -f -
apiVersion: apps/v1
kind: Deployment
metadata:
  name: simple-api
  namespace: simple-api
spec:
  replicas: 1
  selector:
    matchLabels:
      app: simple-api
  template:
    metadata:
      labels:
        app: simple-api
    spec:
      containers:
      - name: simple-api
        image: jkaninda/simple-api:rootless
        resources:
          limits:
            memory: "750Mi"
            cpu: "500m"
        ports:
        - containerPort: 8080
EOF

Advanced deployment with Health check and security context

apiVersion: v1
kind: Namespace
metadata:
  name: simple-api
---
apiVersion: v1
kind: ConfigMap
metadata:
  name: simple-api
  namespace: simple-api
data:
  SPRING_DATA_REDIS_HOST: 'redis-svc'
  SPRING_DATA_REDIS_PORT: '6379'
  SPRING_DATA_REDIS_PASSWORD: 'password'
  ## Insert Redis fake data, requires Redis data source || By default is disabled
  RUN_DATA_SEED: 'true'
---
apiVersion: apps/v1
kind: Deployment
metadata:
  name: simple-api
  namespace: simple-api
spec:
  replicas: 1
  selector:
    matchLabels:
      app: simple-api
  template:
    metadata:
      labels:
        app: simple-api
    spec:
      securityContext:
        runAsUser: 1000
        runAsGroup: 1000
      containers:
        - name: simple-api
          image: jkaninda/simple-api:rootless
          envFrom:
            - configMapRef:
                name: simple-api
          readinessProbe:
            httpGet:
              path: /internal/health/ready
              port: 8080
            initialDelaySeconds: 30
            periodSeconds: 10
            timeoutSeconds: 10
            # HTTP Health Check
          livenessProbe:
              httpGet:
                path: /internal/health/live
                port: 8080
              initialDelaySeconds: 60
              periodSeconds: 30
              timeoutSeconds: 10
          resources:
            limits:
              memory: "750Mi"
              cpu: "500m"
          ports:
            - containerPort: 8080
---
apiVersion: apps/v1
kind: Deployment
metadata:
  name: redis
  namespace: simple-api
spec:
  selector:
    matchLabels:
      app: redis
  template:
    metadata:
      labels:
        app: redis
    spec:
      containers:
        - name: redis
          image: redis:alpine
          command:
            - redis-server
            - --appendonly yes
            - --requirepass password
          resources:
            limits:
              memory: "128Mi"
              cpu: "500m"
          ports:
            - containerPort: 6379
          volumeMounts:
            - mountPath: /data
              name: data
      volumes:
        - name: data
          emptyDir: {}
---
apiVersion: v1
kind: Service
metadata:
  name: redis-svc
  namespace: simple-api
spec:
  selector:
    app: redis
  ports:
    - port: 6379
      targetPort: 6379
---
apiVersion: v1
kind: Service
metadata:
  name: simple-api-svc
  namespace: simple-api
spec:
  selector:
    app: simple-api
  ports:
    - port: 8080
      targetPort: 8080
---

Name		Name	Last commit message	Last commit date
Latest commit History 3 Commits
.github/workflows		.github/workflows
.mvn/wrapper		.mvn/wrapper
data		data
docker		docker
screenshots		screenshots
src		src
.DS_Store		.DS_Store
.gitignore		.gitignore
Dockerfile		Dockerfile
Makefile		Makefile
README.md		README.md
mvnw		mvnw
mvnw.cmd		mvnw.cmd
pom.xml		pom.xml

jkaninda/simple-api

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Simple API

Learning topics:

Docker

Kubernetes

Links:

API Doc

Run on Docker

Create Network

Deploy Simple APi

Advanced Docker deployment

Environment variable from a file

Docker container with Health check

Build Docker image

Screenshots

Interact with the API

RUN on Kubernetes

Create a Kubernetes cluster on Docker using Kind

Install kind (https://kind.sigs.k8s.io/docs/user/quick-start/)

Create cluster

Deploy Simple API

Create Simple API Service

Deploy All

Deploy

Get all resources in the simple-api namespace

Get pods

Kubernetes deployment port forward

Log

Scalability

Ingress

Run as Non-root

Advanced deployment with Health check and security context

About

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