User Bridge v. 062625 "Elm"

(Repo created 062625. Going with tree names for versions or repo variations)

"A centralized authentication service that enables seamless identity sharing between independent business applications."

User Bridge is a centralized auth service that provides an (optionally) shared user system for two or more separate, related business applications. One could call it "federated-authentication-service" or "a microservice for a user system & related authentication", but "user-bridge" is more concise and approachable.

Try it out

git clone git@github.com:pmeaney/user-bridge.git
cd user-bridge

# Copy the env vars example into the .env file
# NOTE: Be sure to generate a JWT_SECRET (e.g. `openssl rand -base64 32`) and make sure it is in .env after you run this copy command:
cp .env-example .env
docker compose up
# open another terminal to run tests: Unit Tests
docker compose exec api-user-bridge sh -c "pnpm test"
# open another terminal to run tests: End to End Tests
docker compose exec api-user-bridge sh -c "pnpm test:e2e"

Architecture: Unified Identity with Application-Specific Memberships

User Bridge creates a unified identity system across multiple applications while keeping application-specific data separate.

This architecture makes it easier to manage projects where users can access multiple related services (For example, a user from SaaS 1 can seamlessly review, join, and then access SaaS 2). It solves a common challenge in multi-application ecosystems: how to provide seamless user experiences without duplicating user data or creating complex cross-application links.

Goals:

• A single source of truth for user identities
• Clear separation between identity and application data
• Flexibility to add more apps in the future
• Proper role and permission management across applications

When a user registers or logs in to one of the apps, this system:

• Creates or verifies their identity in the Auth service
• Creates/updates their app membership
• Returns appropriate tokens

flowchart TD
    subgraph UB["🔐 User-Bridge Auth Microservice"]
        
        subgraph SharedCore["Shared Core Infrastructure"]
            Users[👥 Users Database]
            Auth[🔐 Authentication Logic]
            Memberships[🎫 App Memberships]
            Roles[👑 Roles & Permissions]
        end
        
        subgraph InternalClient["Internal Auth Client"]
            SSO[🔄 SSO Provider]
            Sessions[🍪 Session Management]
            DirectLogin[🚪 Direct Login]
        end
        
        subgraph OAuth2Server["OAuth2 Server Components"]
            Clients[📋 OAuth2 Client Registry]
            Codes[🎟️ Auth Codes]
            Tokens[🔑 Access Tokens]
        end
        
        %% Dependencies within User-Bridge
        SharedCore --> InternalClient
        InternalClient --> OAuth2Server
    end
    
    subgraph Internal["Internal Apps"]
        App1[🏢 Internal SaaS 1]
        App2[🏢 Internal SaaS 2] 
        App3[🏢 Internal SaaS 3]
    end
    
    subgraph ThirdParty["3rd Party Integrated Apps"]
        Flarum[💬 Flarum Forum]
        Nextcloud[☁️ Nextcloud]
        Other[⚡ Other OSS Apps]
    end
    
    %% Internal Auth Flow
    InternalClient --> Internal
    
    %% OAuth2 Flow for Third-Party Apps
    OAuth2Server --> ThirdParty

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