- Table of Contents
| Java | JRE 17 | ✅ |
| Spring | Spring Cloud Contract | ✅ |
| Actuator | ✅ | |
| Spring Security | ✅ | |
| Junit 5 | ✅ | |
| Devtools | ✅ | |
| RestTemplate | ✅ | |
| Maven | Wrapper Script | ✅ |
| Enforcer Plugin | ✅ | |
| Git Commit Id Plugin | ✅ | |
| Containerization | Dockerfile | ✅ |
| Buildpacks | ✅ | |
| Jib | ✅ | |
| Kubernetes | k8s YAML Files | ✅ |
| Startup, Liveness & Readiness Probes | ✅ | |
| Graceful Shutdown | ✅ | |
| Rolling Deployments | ✅ | |
| Kind | ✅ | |
| Skaffold | ✅ | |
| Kustomize | ✅ | |
| Monitoring | Micrometer Prometheus | ✅ |
| Logging | Logback | ✅ |
| Actuator LogLevel Runtime Update | ✅ |
This project uses lombok dependency and requires lombok plugin to be installed from marketplace to resolve IDE compilation issues.
| Command | Purpose |
|---|---|
| ./mvnw clean install | Build the project |
| ./mvnw clean spring-boot:run | Start the application |
| ./mvnw clean spring-boot:run --debug | Start the application with debug logs for a selection of core loggers and logs a conditions report to the console |
| ./mvnw clean package | Build the jar |
| java -jar target/spring-boot-example-1.0-SNAPSHOT.jar | Run packaged application |
| java -Djarmode=layertools -jar target/spring-boot-example-1.0-SNAPSHOT.jar list | List layers from the jar that can be extracted |
| ./mvnw spring-boot:build-image | Build docker image using buildpacks |
| ./mvnw spring-boot:build-image -Dspring-boot.build-image.imageName=spring-boot-example | Build docker image with provided image name |
| docker build -t spring-boot-example . | Build docker image using Dockerfile |
| ./mvnw compile jib:dockerBuild -Dimage=spring-boot-example | Build docker image using jib |
| docker run --name spring-boot-example -p 8080:8080 spring-boot-example:latest | Run docker container |
Set jvm property -Dspring.profiles.active=prod to use application-prod.properties
Check ExampleController class for list of supported API paths.
Set jvm property -Dlogging.level.com.springboot.example=debug to override and enable debug logs for the class.
Includes below dependencies:
- spring-webmvc
- spring-web
- tomcat-embed-[core, el, websocket]
- fasterxml jackson
- slf4j, log4j, logback
- yaml
Includes below dependencies:
- JUnit 4 & 5
- Spring Test & Spring Boot Test
- AssertJ
- Hamcrest
- Mockito
- JSONassert
- JsonPath
Get health status:
http://localhost:8080/actuator/health
Get readiness and liveness status:
http://localhost:8080/actuator/health/liveness
http://localhost:8080/actuator/health/readiness
Get build and git info:
http://localhost:8080/actuator/info
Get metrics for an endpoint:
http://localhost:8080/actuator/metrics/http.server.requests?tag=uri:/
Get prometheus metrics:
http://localhost:8080/actuator/prometheus
Spring cloud contracts are available in test/resources/contracts folder.
When you run maven build, the contract test class will be created in generated-test-sources folder and the stubs in target/stubs folder.
mvn package will generate the stubs jar which can be deployed to any repository.
Some actuator endpoints are secured with IP address restriction.
Accessing http://localhost:8080/actuator/config will fail with Access Denied error whereas http://127.0.0.1:8080/actuator/config will return response.
There are multiple ways to containerize your app.
| Approach | Image Size | Comments |
|---|---|---|
| Paketo Buildpacks | ~270 MB | |
| Jib | ~260 MB | Jib builds optimized Docker and OCI images for your Java applications without a Docker daemon |
| Dockerfile - jlink module approach with debian as base image | ~150 MB | - jlink helps to create a custom runtime with only the required modules - Using debian as base image has following advantages 1. presence of libc 2. performance issues of Alpine for certian programming languages 3. suitable for testing with tools available out of the box |
For Dockerfile approach, you can get the necessary JDK modules needed to run your application with below command:
jdeps --ignore-missing-deps -q -recursive --multi-release 17 --print-module-deps --class-path 'target/libs/*' target/spring-boot-example-1.0-SNAPSHOT.jar > jre-deps.infoTo run the spring boot application in your local kubernetes cluster, follow below steps.
Run below script which will set up a local registry, create a kind kubernetes cluster and link with the registry.
./kind/kind-with-registry.sh
Creating cluster "kind" ...
✓ Ensuring node image (kindest/node:v1.21.1) 🖼
✓ Preparing nodes 📦
✓ Writing configuration 📜
✓ Starting control-plane 🕹️
✓ Installing CNI 🔌
✓ Installing StorageClass 💾
Set kubectl context to "kind-kind"
You can now use your cluster with:
Build the image by specifying the registry address in the image name:
# image name defined in pom
./mvnw spring-boot:build-image
# alternatively
./mvnw spring-boot:build-image -Dspring-boot.build-image.imageName=localhost:5000/apps/spring-boot-example
Push the image to the local registry:
docker push localhost:5000/apps/spring-boot-example
Apply the manifest files to create the deployment and service components:
kubectl apply -f k8s
Check the status to ensure everything is working as expected:
kubectl get all
NAME READY STATUS RESTARTS AGE
pod/k8s-spring-boot-example-775fcbf645-mzth5 1/1 Running 0 13s
NAME TYPE CLUSTER-IP EXTERNAL-IP PORT(S) AGE
service/k8s-spring-boot-example ClusterIP 10.96.223.252 <none> 80/TCP 13s
service/kubernetes ClusterIP 10.96.0.1 <none> 443/TCP 72s
NAME READY UP-TO-DATE AVAILABLE AGE
deployment.apps/k8s-spring-boot-example 1/1 1 1 13s
NAME DESIRED CURRENT READY AGE
replicaset.apps/k8s-spring-boot-example-775fcbf645 1 1 1 13s
To access the app, port forward to the service:
kubectl port-forward service/k8s-spring-boot-example 8080:80
Skaffold makes some enhancements to our development workflow when using Kubernetes
- Build the app and create the container (buildpacks)
- Push the container to the registry (Docker)
- Apply the deployment and service YAMLs
- Stream the logs from the Pod to your terminal
- Automatically set up port forwarding
Run the following command to have Skaffold build and deploy our application to Kubernetes.
skaffold dev --port-forward
To remote debug the application, run below skaffold command:
skaffold debug --auto-sync --port-forward
Create a remote debug profile in your IDE.
Run in debug mode to attach to the remote port. Add a breakpoint to the code and make a request to start debugging.
Kustomize allows us to customize deployments to different environments.
We can start with a base set of resources and then apply customizations on top of those.
Features
- Allows easier deployments to different environments/providers
- Allows you to keep all the common properties in one place
- Generate configuration for specific environments
- No templates, no placeholder spaghetti, no environment variable overload
Run below command to build QA customization with replica count as '2'
kustomize build kustomize/qa | kubectl apply -f -
Run below command to use Kustomize files with Scaffold:
skaffold dev -f skaffold-kustomize.yaml -p qa --port-forward
Ostara is a desktop application that provides various features to monitor and interact with Spring Boot Applications via Actuator.
Create an Instance in Ostara by adding below Actuator URL.
You can view the dashboard, metrics and various features powered by Spring Boot Actuator endpoints.
