This is a classic scenario faced by growing digital health platforms: how do you provide unified, secure login and RBAC authorization across distinct user “verticals” (Patient, Doctor, Hospital, Nurse) without login conflicts or fractured user experiences?

Let’s break down the ideal solution as a modern, scalable, and secure microservices architecture—with a clear expert recommendation for your context.
This includes architecture diagram description, best practices, and a practical suggestion for your current Laravel/microservice stack.

1. Recommended Architecture Overview

Adopt a Centralized Auth System with RBAC (Option 2 – Central Auth Domain, e.g. `auth.myhospitalnow.com`)

Why?
- Avoids login/session conflicts.
- Enables SSO (Single Sign-On) for users who might switch roles (Doctor who is also a Patient).
- Simplifies integration for web/mobile apps.
- Industry standard for modern SaaS/multi-tenant systems.

2. High-Level Architecture Diagram Description

                        +--------------------+
                        | External Identity  |
                        | Providers (SSO,    |
                        | Google, Azure AD)  |
                        +----------+---------+
                                   |
                                   v
                      +-----------------------------+
                      |       Auth Service          |
                      | (OAuth2/JWT, Login,         |
                      |  Token Issuance/Refresh,    |
                      |  Federation, RBAC)          |
                      +----+------------------+-----+
                           |                  |
              +------------+--------+         |
              |                     |         |
              v                     v         v
      +---------------+   +-------------------+---------------------+
      | User Mgmt     |   |     Authorization Service (RBAC)        |
      | (Profile,     |   | - Enforce Policies, Validate Roles/Perm |
      | Role Assign,  |   +-----------+---------------+-------------+
      | Registration) |               |               |
      +-------+-------+               |               |
              |                       |               |
              +----------+------------+               |
                         |                            |
                   +-----v-----+                +-----v------+
                   | Identity  | <------------> | Audit Log  |
                   | Store     |                | & Policy   |
                   | (SQL/LDAP)|                | Store      |
                   +-----------+                +------------+

---API Gateway (Token Validation, Routing, Claims Propagation)---
                               |
                +--------------+-------------------------------+
                |              |               |               |
                v              v               v               v
         [Patient Service]  [Doctor Service]  [Hospital Service] [Nurse Service]
         (Resource MS)      (Resource MS)     (Resource MS)     (Resource MS)
                |               |               |               |
          +-----+---------------+---------------+---------------+
          |      Inter-Service AuthZ/Claims via JWT/OAuth2      |
          +-----------------------------------------------------+

3. Component Explanation & Best Practices

A. Central Auth Service (`auth.myhospitalnow.com`)

Handles:
- Login (email/mobile/social)
- Issues JWT/OAuth2 tokens (short-lived + refresh)
- Handles federated login (Google, Azure, LDAP, etc.)
- Stateless authentication—scalable for web & mobile
Best Practice:
- Use JWT (or opaque OAuth2 tokens with introspection endpoint).
- Tokens store userID, role(s), tenant info, and claims.
- Issue refresh tokens for mobile/web session continuity.

B. Authorization Service (RBAC Engine)

Handles:
- Decoupled from authentication.
- On each API/resource request, validates if role (Doctor/Patient/Nurse/Hospital) has required permission.
- Can implement policy-as-code (e.g., OPA), or Laravel’s built-in policies, but as a service.
Best Practice:
- Enforce Principle of Least Privilege.
- Keep all permission decisions and audit logs centrally.

C. User Management Service

Handles:
- Registration, role assignment (e.g., change role, assign multiple roles)
- Profile edits, password resets, etc.

D. Resource Microservices

Each microservice (e.g., Patient, Doctor, Hospital) delegates all authentication & authorization to the centralized auth system.
Best Practice:
- Resource MS never directly manage auth/session data—verify JWT on each request (zero trust).
- Only act if RBAC check passes.

E. API Gateway (or Service Mesh)

Handles:
- Routes external/internal traffic to services.
- Validates JWT, checks signature, and extracts claims.
- Injects user claims into request headers/context for downstream microservices.
Best Practice:
- Use Envoy, Kong, NGINX, or AWS API Gateway, etc.
- Terminate tokens at gateway, propagate verified claims to resource MS.
- Supports rate limiting, threat protection, CORS.

F. Identity Store (DB/Directory)

Central DB for:
- Users
- Roles
- Permissions
- Role-user and permission-role mappings
Best Practice:
- Use normalized SQL for flexibility, or LDAP if heavy directory needs.

G. External Identity Providers (SSO, Federation)

Optional:
- Let users login with Google, Apple, or Azure AD, with mapped roles in your system.

4. RBAC Decision Flow

Example: Patient tries to book a hospital appointment

Login: Patient logs in at auth.myhospitalnow.com. Receives JWT token with role=Patient.
API Request: Patient App calls API Gateway with JWT.
Gateway: Verifies JWT (signature, expiry), extracts claims (userID, role=Patient).
Gateway: Forwards request + user claims to PatientService.
PatientService: Requests RBAC decision from Authorization Service (e.g., “Can this user with role=Patient create booking?”).
Authorization Service: Checks policy, returns “Allowed/Denied”.
PatientService: Proceeds if allowed, otherwise returns HTTP 403.
Audit: All attempts logged centrally.

5. Addressing Your Current Problem

Problem: Patient login session does not work for doctors/hospitals and vice versa—because session/cookies are isolated per microservice.

Recommended Fix:
Unify all authentication at a single Auth Service (auth.myhospitalnow.com) using stateless tokens (JWT or OAuth2).

All logins redirect to auth service, which issues tokens to web/app clients.
Token is valid across all microservices and portals—no conflict.
Each app (web or Android/iOS) uses the token in the Authorization header for every API call.

6. Implementation Steps (Laravel + Modern Stack)

Deploy a central Laravel-based Auth Service (using Laravel Passport or Laravel Sanctum for OAuth2/JWT).
Refactor all microservices to NOT handle their own sessions; instead, validate incoming JWT tokens.
Integrate API Gateway (Kong, Nginx, or Laravel-based) to handle token verification and request routing.
Move user/role/permission tables to a central identity DB, accessible to Auth/Authorization services only.
Resource microservices call the Authorization service before processing sensitive requests.
Mobile apps use OAuth2 flows to obtain/refresh tokens.

7. Best Practices

Zero Trust: Every call, internal or external, is authenticated and authorized. No "trusted" network.
Principle of Least Privilege: Roles/permissions are as granular as needed; users get only what they need.
Audit Logging: Every RBAC decision, login, and sensitive action is logged for compliance.
Token Expiry: Use short-lived JWT, long-lived refresh tokens.
Federation Ready: Support for Google/Apple/Azure SSO for convenience.

8. Annotated Visual Architecture

(For final doc, use a visual tool like draw.io, Lucidchart, or Excalidraw to illustrate the described flow. See the text diagram above as a guide. I can generate an image if you need!)

9. Summary Table – Option Comparison

| Option | Pros | Cons |
| ---------------------- | ---------------------------------------------------- | --------------------------------- |
| Separate Auth | Simple, isolated, no conflicts | Fragmented UX, can't share login |
| Central Auth (Rec) | Unified login, SSO, easier to scale, RBAC everywhere | Initial migration work, SSO setup |

**→ Industry best practice is centralized, stateless authentication and delegated authorization via a dedicated Auth Service.**

10. Next Steps

Choose Option 2: Central Auth Service (auth.myhospitalnow.com)
Prototype using Laravel Passport/Sanctum for JWT OAuth2
Integrate API Gateway (Kong/NGINX or similar)
Refactor resource microservices to delegate auth checks.
Add RBAC with granular policies, central DB, and audit logs.

Let me know if you want:

A detailed sequence diagram
A ready-to-use architecture image
Sample Laravel code snippets for each component
Migration plan from your current setup

Just say the word!