Create a RESTful API Service with Spring Boot, dockerize & deploy to Kubernetes
We’ll first create a new Spring Boot Application implementing a basic HTTP GET service endpoint. Once our application is up and running we can go ahead and create a docker image and launch a docker container to test our service out. And finally, we’ll take our docker image and deploy it to a Kubernetes Cluster for a production grade deployment.
Dockerfile
We use the stock jre image from openjdk to run our application inside of:
FROM openjdk:8-jre-alpine
COPY build/libs/k8-byexamples-spring-rest-0.0.1-SNAPSHOT.jar /application.jar
CMD ["java", "-jar", "/application.jar"]Makefile (optional)
I’ve created a simple Makefile to speed things up. Simply make all to build & push the docker image. Similarly you can make k8/install to install the kubernetes manifests:
VERSION ?= $(shell git rev-parse HEAD)
APP ?= k8-byexamples-spring-rest
IMAGE ?= gcr.io/matthewdavis-byexamples/$(APP):$(VERSION)
.PHONY: build
all: build push
build:
docker build -t $(IMAGE) .
run:
docker run -p 8080:8080 $(IMAGE)
push:
docker push $(IMAGE)
k8/install:
kubectl apply -f manifests/
k8/delete:
kubectl delete -f manifests/TestRestController.java
This is a simple REST controller that responds to HTTP POST requests (i.e.: https:///test/echo):
package com.example.k8byexamplesspringrest;
import org.springframework.http.HttpStatus;
import org.springframework.http.ResponseEntity;
import org.springframework.web.bind.annotation.PostMapping;
import org.springframework.web.bind.annotation.RequestBody;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;
@RestController
@RequestMapping("/test")
public class TestRestController {
@PostMapping("/echo")
public ResponseEntity<?> testResponse(@RequestBody String body) {
return new ResponseEntity<>("You said: " + body, HttpStatus.OK);
}
}