Add dependency graph ingestion module for service topology analysis

[devin-ai-integration]

Summary

Introduces a new dependency-graph Maven module that parses the bank application's infrastructure configuration files and normalizes them into a typed graph model. This enables programmatic analysis of service dependencies for incident investigation, impact analysis, and change management.

Graph Model

• Nodes with typed categories: SERVICE, DATABASE, MESSAGE_BROKER, EVENT_STORE, MAIL_SERVER, GATEWAY, DISCOVERY
• Edges with typed relationships: HTTP, JDBC, AMQP, SMTP, EUREKA_REGISTER, GATEWAY_ROUTE, AXON
• Full metadata support on both nodes and edges (ports, database names, predicates, URIs, etc.)

Parsers

Parser	Input	What it extracts
DockerComposeParser	docker-compose.yml	Service topology, depends_on edges, inferred DB/Axon/mail/RabbitMQ nodes from env vars
EurekaRegistrationParser	application.properties / application.yml	Eureka registration edges, JDBC connections, Axon Server, mail server
GatewayRouteParser	Gateway application.yml	Explicit lb:// and http:// routes, discovery-first routing mode, route predicates

How this improves incident investigation

When a service fails or behaves unexpectedly, responders need to quickly answer: "What does this service depend on, and what depends on it?" Today, that requires reading Docker Compose files, application properties, and Feign client annotations across multiple modules.

This module automates that by building a queryable graph from the existing config files. With the graph, you can:

• Trace blast radius: given a failing MySQL instance, instantly find every service with a JDBC edge to it
• Identify upstream/downstream impact: if account-service is down, query incoming edges to see which gateway routes and Feign clients are affected
• Detect infrastructure drift: compare the Docker Compose graph against Eureka registration graphs to find services that are defined but not registering (or vice versa)
• Support runbook automation: feed the graph into alerting/triage tools to auto-correlate alerts with service dependencies

Test coverage

59 tests across 4 test classes covering:

• Valid inputs from the actual bank repo configurations
• Malformed YAML, null/blank content, missing required keys
• Map-style and list-style depends_on
• Map-style and list-style environment variables
• RabbitMQ, Axon, SMTP infrastructure inference
• Discovery-first vs explicit gateway routing
• Graph model operations (merge, filtering, equality, metadata immutability)

Review & Testing Checklist for Human

• Verify the parsers produce correct graphs for the actual docker-compose.yml and application.properties files in this repo — run mvn test -pl dependency-graph
• Review the NodeType and EdgeType enums to confirm they cover the infrastructure types relevant to your deployment
• Check that the DockerComposeParser correctly infers MySQL, Axon, and mail connections from environment variable patterns in your compose file

Notes

• The module is a pure library with no Spring Boot dependency — only SnakeYAML for parsing. This keeps it lightweight and usable in CLI tools, CI pipelines, or runtime services.
• The DependencyGraph.merge() method allows combining graphs from multiple parsers into a unified view.
• The authentication-service appears as user-service in docker-compose.yml — both are captured correctly by their respective parsers.

Link to Devin session: https://app.devin.ai/sessions/75cc02940ecf4523a51f2964865feee2
Requested by: @achalc

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