0003. Authentication and User Management Approach

Status: Accepted Date: 2025-10-08 Context: Continuation of ADR-0002 (Quarkus adoption); defines authentication, authorization, and user data management.

Context

The platform requires secure, standards-based authentication and user management for both web and API clients. Key requirements include:

Support for OAuth 2.0 / OIDC flows (for future integration with third-party login providers).
Secure token-based access for API consumers.
Minimal operational burden for the small engineering team.
Compatibility with Quarkus security extensions and AWS deployment model (ECS + Aurora PostgreSQL).
Flexibility to evolve toward multi-tenant and enterprise scenarios.

Two primary models were considered:

Application-managed identity using Quarkus Security JPA, storing credentials and roles in our own database.
Delegated identity management using a managed OIDC provider, specifically AWS Cognito.

Decision

We will adopt AWS Cognito as the primary authentication and user-management service. Quarkus will integrate via the quarkus-oidc extension, treating Cognito as an external OpenID Connect provider.

Rationale

Consideration	Cognito (Chosen)	Quarkus Security JPA (Not Chosen for now)
Operations	Fully managed service, handles signup, password reset, MFA, social login	Requires us to store and hash passwords, build account flows
Security posture	Offloads credential handling and compliance to AWS	Higher risk surface; must implement secure storage and policies ourselves
Scalability	Auto-scales with user base; integrates with AWS IAM	Scales with our Aurora DB; more tuning required
Integration	Works natively with Quarkus OIDC and ALB OIDC auth	Tight coupling to DB schema; limited federation options
Future flexibility	Supports enterprise federation (SAML, OIDC, AD)	Limited to in-app users unless refactored later

Given limited operational capacity at this stage, Cognito provides a secure, standards-compliant baseline while allowing later customization if business needs demand internal user management.

Implementation Outline

In Quarkus

quarkus.oidc.auth-server-url=https://cognito-idp.<region>.amazonaws.com/<user-pool-id>
quarkus.oidc.client-id=<client-id>
quarkus.oidc.credentials.secret=<client-secret>
quarkus.oidc.application-type=web-app
quarkus.oidc.authentication.scopes=openid,profile,email

Tokens (JWTs) are verified automatically by Quarkus OIDC.
Role/claim mapping handled via Cognito groups or custom attributes.
Application endpoints protected via @RolesAllowed and SecurityIdentity.

Persistence Layer

Aurora PostgreSQL remains the primary store for domain data.
Minimal user references (e.g. Cognito sub UUID, profile metadata) stored as foreign keys — no passwords.

Local Development

Use AWS Cognito in a development sandbox environment using AWS free tier.
Quarkus's quarkus.oidc.devservices.enabled=true can spin up a local OIDC provider automatically when needed for unit testing.
Cost-effective: AWS Cognito free tier (50,000 monthly active users) is significantly cheaper than LocalStack Pro ($40/user/month).

Future Alternatives

If business needs require:

Tighter integration or internal credential control, migrate selectively to Quarkus Security JPA (passwords stored in Aurora).
Cross-platform login (Google, Apple, LinkedIn), leverage Cognito’s Identity Federation features.
Enterprise SSO, integrate existing IdPs via Cognito Federation or replace Cognito with Keycloak.

Consequences

Positive

Removes responsibility for credential lifecycle, MFA, and compliance.
Simplifies Quarkus configuration (OIDC instead of JPA-based security).
Scales seamlessly within AWS ecosystem.

Negative / Trade-offs

Introduces external dependency (Cognito availability, cost model).
Requires internet connectivity for development (vs local emulation).
Less direct control over user-table schema and credential policies.