Case Study - Kubernetes Yml Comparison

📖 Information

Project Definition (Kubernetes YML Comparison)

A Spring Boot service that compares two Kubernetes YAML files and produces: (1) a structured JSON diff (merged left/right lines + stats) and (2) a GitHub-like HTML snippet for visual review. Each successful comparison is logged as a DiffLog (filenames, SHA-256 hashes, counters, IP, timestamp). All JSON responses are wrapped in CustomResponse<T>.

End-to-end flow (compare APIs):

• Client sends a multipart request with two files: left and right. Optionally pass a JSON part options with { "ignoreWhitespace": true|false }.
• 2 sample files whose names are deployment-old.yaml and deployment-new.yaml are defined underneath files folder
• Service normalizes/decodes input, runs a line diff, builds a left/right-aligned merged view, computes stats (added / deleted / unchanged), and renders a GitHub-like HTML snippet.
• Returns either:
  • 200 OK JSON model (DiffResult) at /api/diff/compare
  • 200 OK HTML snippet at /api/diff/comparehtml
  Successful runs are persisted as DiffLog via AOP.

Diff logging (AOP):

An aspect (@LoggableDiff) captures successful comparisons and stores: left/right filenames, SHA-256 (Base64URL) hashes, added/deleted/unchanged counts, requester IPv4, and createdAt.

Error semantics:

• 400 Bad Request — Empty input side (left/right), invalid/too large files (≤ 2 MB)
• 406 Not Acceptable — Client insists on text/html but only an error JSON is available
• 500 Internal Server Error — Unexpected failures (e.g., crypto hashing)

OpenAPI (Swagger):

Explore the API and schemas at: http://localhost:1928/swagger-ui/index.html (port configurable).

Explore Rest APIs

Endpoints Summary

Method	URL	Description	Request Body	Headers/Path	Response	Status Codes
POST	/api/diff/compare	Compare two YAML files and return JSON diff + stats	Multipart: left: file right: file options: JSON { "ignoreWhitespace": true|false } (optional)	Accept: application/json	CustomResponse<DiffResultDto> DiffResultDto: lines[] (left/right line numbers + type + text), stats, html	200, 400
POST	/api/diff/comparehtml	Compare two YAML files and return HTML snippet directly	Multipart: left: file right: file options: JSON { "ignoreWhitespace": true|false } (optional)	Accept: text/html	HTML snippet (GitHub-like two-column diff)	200, 400, 406

Technologies

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• Java 25
• Spring Boot 3.0
• Restful API
• Open Api (Swagger)
• Maven
• Junit5
• Mockito
• Integration Tests
• Mapstruct
• Docker
• Docker Compose
• CI/CD (Github Actions)
• Postman
• Prometheus
• Grafana
• Kubernetes
• JaCoCo (Test Report)
• AOP
• Sonarqube

Postman

Import postman collection under postman_collection folder

Prerequisites

Define Variable in .env file

COMPARE_DB_IP=localhost
COMPARE_DB_PORT=3306
DATABASE_USERNAME={MY_SQL_DATABASE_USERNAME}
DATABASE_PASSWORD={MY_SQL_DATABASE_PASSWORD}

Open Api (Swagger)

http://localhost:1928/swagger-ui/index.html

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JaCoCo (Test Report)

After the command named mvn clean install completes, the JaCoCo report will be available at:

target/site/jacoco/index.html

Navigate to the target/site/jacoco/ directory.

Open the index.html file in your browser to view the detailed coverage report.

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Maven, Docker and Kubernetes Running Process

Maven Run

To build and run the application with Maven, please follow the directions shown below;

$ git clone https://github.com/Rapter1990/kubernetesymlcompare.git
$ cd kubernetesymlcompare
$ mvn clean install
$ mvn spring-boot:run

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Docker Run

The application can be built and run by the Docker engine. The Dockerfile has multistage build, so you do not need to build and run separately.

Please follow directions shown below in order to build and run the application with Docker Compose file;

$ cd kubernetesymlcompare
$ docker-compose up -d

If you change anything in the project and run it on Docker, you can also use this command shown below

$ cd kubernetesymlcompare
$ docker-compose up --build

To monitor the application, you can use the following tools:

• Prometheus:
  Open in your browser at http://localhost:9090
  Prometheus collects and stores application metrics.

• Grafana:
  Open in your browser at http://localhost:3000
  Grafana provides a dashboard for visualizing the metrics.
  Default credentials:

  • Username: admin
  • Password: admin

Define prometheus data source url, use this link shown below

http://prometheus:9090

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Kubernetes Run

To run the application, please follow the directions shown below;

• Start Minikube

$ minikube start

• Open Minikube Dashboard

$ minikube dashboard

• To deploy the application on Kubernetes, apply the Kubernetes configuration file underneath k8s folder

$ kubectl apply -f k8s

• To open Prometheus, click tunnel url link provided by the command shown below to reach out Prometheus

minikube service prometheus-service

• To open Grafana, click tunnel url link provided by the command shown below to reach out Prometheus

minikube service grafana-service

• Define prometheus data source url, use this link shown below

http://prometheus-service.default.svc.cluster.local:9090

Sonarqube

• Go to localhost:9000 for Docker and Go there through minikube service sonarqube for Kubernetes
• Enter username and password as admin
• Change password
• Click Create Local Project
• Choose the baseline for this code for the project as Use the global setting
• Click Locally in Analyze Method
• Define Token
• Click Continue
• Copy sonar.host.url and sonar.token (sonar.login) in the properties part in pom.xml
• Run mvn sonar:sonar to show code analysis

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Docker Image Location

https://hub.docker.com/repository/docker/noyandocker/kubernetesymlcompare/general

📸 Screenshots

Click here to show the screenshots of project

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Contributors

• Sercan Noyan Germiyanoğlu