ArnauAregall / micronaut-kotlin-petclinic-clean-architecture

Sample repository to explore microservices architecture patterns using Micronaut and Kotlin

micronaut-kotlin-petclinic-clean-architecture

Sample repository to explore microservices architecture patterns using Micronaut and Kotlin while following clean architecture/ports and adapters.

Tech stack:

• Kotlin
• Gradle
• GraalVM
• Micronaut
• Project Reactor
• Postgres
• Flyway
• Hibernate / R2DBC
• Apache Kafka
• Redis
• Keycloak
• Docker
• Testcontainers

The goal is to mimic the well known project Spring PetClinic but using Micronaut and following a distributed architecture design.

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Requirements

The application requires JDK 21 on a GraalVM distribution.

Is recommended to use SDKMAN! to install the JDK.

$ curl -s "https://get.sdkman.io" | bash
$ sdk install java 21.0.2-graalce
$ sdk use java 21.0.2-graalce

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Running the application

Add the following entry to your /etc/hosts:

# Required for Keycloak issuer matching 
127.0.0.1 keycloak.local

Also see .env file for needed environment variables.

Containerized with docker-compose

Build Micronaut applications Docker images:

./gradlew dockerBuildNative

Start all the applications and infrastructure containers:

docker compose --profile petclinic up

Local development mode

1. Start infrastructure dependencies containers

docker compose up

2. identity-service

./gradlew :identity-service:nativeCompile # or from your IDE with the env vars below

export MICRONAUT_ENVIRONMENTS=dev OAUTH2_CLIENT_SECRET=${IDENTITY_SERVICE_OAUTH2_CLIENT_SECRET}; ./identity-service/build/native/nativeCompile/identity-service

3. pet-service

./gradlew :pet-service:nativeCompile # or from your IDE with the env vars below

export MICRONAUT_ENVIRONMENTS=dev OAUTH2_CLIENT_SECRET=${PET_SERVICE_OAUTH2_CLIENT_SECRET}; ./pet-service/build/native/nativeCompile/pet-service

4. vet-service

./gradlew :vet-service:nativeCompile # or from your IDE with the env vars below

export MICRONAUT_ENVIRONMENTS=dev OAUTH2_CLIENT_SECRET=${VET_SERVICE_OAUTH2_CLIENT_SECRET}; ./vet-service/build/native/nativeCompile/vet-service

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Keycloak notes

How to import Keycloak OpenID realm

• Open your browser and head to Master Realm Admin Console page.
• Login with Keycloak Administrator credentials.
• Create a new realm named petclinic by importing the file ./keycloak/realm/petclinic-realm.json.

OpenID client settings:

• Valid Redirect URIs:

  http://localhost:${server.port}/oauth/callback/keycloak 
  

Client Scope

Create a new client scope for both identity-service and pet-service OAuth clients.

The client scope should contain an Audience mapper that adds both services as audience in the aud claim of the JWT token.

Fixes:

13:54:48.623 [default-nioEventLoopGroup-1-3] DEBUG i.m.s.t.jwt.validator.JwtValidator - Validating signed JWT
13:54:48.645 [default-nioEventLoopGroup-1-3] DEBUG i.m.s.t.j.s.jwks.JwksSignatureUtils - JWT Key ID: gOb1j1sIHJKVTacOrsKLH-LaQEkK_rGnSGnWnVXFZ18
13:54:48.645 [default-nioEventLoopGroup-1-3] DEBUG i.m.s.t.j.s.jwks.JwksSignatureUtils - JWK Set Key IDs: gOb1j1sIHJKVTacOrsKLH-LaQEkK_rGnSGnWnVXFZ18,2avwDqmRvQW-nJcEZQiIjoIY5wsNyarebI6kziBY2oU
13:54:48.646 [default-nioEventLoopGroup-1-3] DEBUG i.m.s.t.j.s.jwks.JwksSignatureUtils - Found 1 matching JWKs
13:54:48.651 [default-nioEventLoopGroup-1-3] DEBUG i.m.s.o.c.IdTokenClaimsValidator - audiences 'identity-service' does not contain client id 'pet-service'