Table of Contents

• Description
• Technologies
• Usage
• Application Configuration
• To do

Description

A Spring Boot 3.5 application that provides a REST API for retrieving non-forked GitHub repositories for a given username, including branch names and their last commit SHA.

This project uses modern Spring Boot features like RestClient, Java 21 virtual threads, and a clean minimal layered architecture.

Technologies

Java: 21

Spring Boot: 3.5.4

Tomcat: 10.1.43

Spring Framework: 6.2.9

GitHub API: v3

Usage

Endpoint

GET /api/repositories/{username}

Returns all non-forked repositories for the specified GitHub user, including their branches and last commit SHA. Response example:

[
  {
    "repositoryName": "Spoon-Knife",
    "ownerLogin": "octocat",
    "branches": [
      {
        "name": "main",
        "lastCommitSha": "d0dd1f61b33d64e29d8bc1372a94ef6a2fee76a9"
      }
    ]
  }
]

Application Configuration

These are the relevant properties used in the application.yml file:

spring:
  threads:
    virtual:
      enabled: true

• While GitHub rate limiting currently limits concurrency, virtual threads are added proactively — to be ready for future scale when concurrency increases and limits are lifted.

github:
  api:
    token: ${github-token:#{null}}

• The GitHub API token can be set as an environment variable github-token or left empty for unauthenticated requests (which have lower rate limits (60 compared to 5000 per hour)).

To do

• Rate Limiting: GitHub enforces both primary and secondary rate limits. The current implementation does not yet include rate-limit handling. For details, refer to the GitHub rate limit documentation.

• Async Error Edge Case: When fetching branches asynchronously, there is a potential race condition: if a repository is deleted after listing but before fetching its branches, the request may fail with a 404 error. Alternatively, we could handle this case gracefully and return data for the remaining repositories.