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Azure AD as Central IDP, A;; Cloud trust,OIDC/Oauth2/Refresh Token
- Anand Nerurkar
- Oct 25
- 13 min read
Perfect — now let’s break down authentication & authorization flows in a multi-cloud hybrid scenario (Azure, AWS, On-prem) using Azure AD as the central IdP.
I’ll explain step by step, including OIDC / OAuth2 tokens, refresh tokens, and how they are used.
This is exactly what an Enterprise Architect would explain in an interview.
We’ll use Amit R as the example user.
1️⃣ Core Concepts
Term | Role / Description |
Azure AD | Central Identity Provider (IdP). Performs authentication and issues tokens. |
Authentication | Verifying the user is who they claim to be (login + MFA). |
Authorization | Deciding what the user can do (mapped to roles / permissions / groups). |
OIDC Token (ID Token) | JWT containing identity claims (who the user is). |
OAuth2 Access Token | JWT used to authorize API access to resources. |
Refresh Token | Long-lived token used to get new access tokens without re-authentication. |
Federation | Trust relationship between Azure AD (IdP) and other systems (AWS, On-prem). |
2️⃣ Step-by-Step Flow — Azure App (Azure Region A)
Scenario: Amit logs into the Azure Lending App.
Amit navigates to https://lending.bank.com.
App detects no active session → redirects Amit to Azure AD login page.
Amit authenticates (username + password + MFA).
Azure AD validates credentials → authenticates Amit.
Azure AD issues tokens:
ID Token (OIDC) → contains claims: sub, email, groups, roles.
Access Token (OAuth2) → scopes for API access (e.g., lending.read, lending.write).
Refresh Token → can request new access token without login.
App validates ID Token signature using Azure AD JWKS endpoint.
App extracts claims to enforce authorization (RBAC).
✅ Key Point: Tokens are JWTs, signed by Azure AD, and trusted by all services configured for Azure AD.
3️⃣ Step-by-Step Flow — AWS App (AWS Region B)
Scenario: Amit wants to access AWS-hosted Analytics service.
Amit clicks AWS app link → app redirects him to Azure AD (federated IdP) via SAML/OIDC.
Amit is already authenticated in Azure AD → no additional login.
Azure AD issues a SAML Assertion / OIDC token containing:
User identity (sub, email)
Group membership / role claims (e.g., Analytics_ReadOnly)
AWS receives the token and performs STS AssumeRoleWithSAML / OIDC:
Creates temporary IAM credentials (access key, secret key, session token) valid 15–60 min.
AWS services validate IAM role policies → authorize Amit’s API / console access.
If Amit’s session expires → uses Azure AD refresh token to get a new token and repeat STS role assumption.
✅ Key Point: Azure AD centralizes authentication, AWS enforces authorization locally using IAM roles mapped from claims.
4️⃣ Step-by-Step Flow — On-Prem Systems (Region C)
Scenario: Amit accesses Core Banking System (CBS) on-prem.
On-prem AD is synchronized with Azure AD via Azure AD Connect.
Amit’s groups and attributes are synced to LDAP/AD groups.
Amit logs into CBS portal → Azure AD acts as IdP (SAML/OIDC) if supported.
Otherwise, Amit uses local AD credentials provisioned from Azure AD.
CBS app validates token (or credentials) → maps group membership to authorization roles.
Access is granted per policy (e.g., LoanViewer, KYC_ReadOnly).
✅ Key Point: Authentication still comes from Azure AD, local AD enforces authorization.
5️⃣ Token Lifecycles Across Multi-Cloud
Token Type | Purpose | Lifetime | Usage |
ID Token (OIDC) | Identifies user to app | ~1 hour | App extracts identity claims |
Access Token (OAuth2) | Authorize API calls | 15–60 min | Used in Authorization header (Bearer token) |
Refresh Token | Obtain new access tokens without login | Days / weeks | Only presented to Azure AD token endpoint |
AWS Temporary Credentials | Map federated identity to IAM role | 15–60 min | Access AWS APIs / services |
Important Points:
All multi-cloud services trust Azure AD tokens via federation (AWS, on-prem apps supporting SAML/OIDC).
Refresh token is never used directly by cloud services; app or client uses it to request new access token from Azure AD.
Short-lived access tokens reduce risk if stolen — temporary credentials in AWS expire automatically.
6️⃣ Example — Amit Access Flow (End-to-End)
[ Amit R ]
│
▼
[ Browser / Mobile App ] --Request access--> [ Azure Lending App ]
│
▼
[ Azure AD ] --AuthN / MFA--> ID Token + Access Token + Refresh Token
│
▼
[ Lending App / APIs ] --Validate token & enforce roles--> App access
│
▼
[ AWS Analytics App ] --OIDC/SAML Federation--> AWS STS temporary credentials
│
▼
[ AWS Services ] --Authorization via IAM roles--> Access granted
│
▼
[ On-Prem CBS ] --Token / AD credentials--> AD enforces roles
7️⃣ Best Practices in Production
Use short-lived tokens in AWS, refresh tokens only in client apps.
Token caching in apps with proper expiration handling.
mTLS for service-to-service calls inside clouds.
Token introspection for legacy apps (validate JWT with Azure AD).
Audit & SIEM integration: all token issuance & usage events logged.
Conditional Access: MFA, location, device compliance enforced centrally via Azure AD.
SailPoint Governance: monitors entitlements and ensures Azure AD groups, AWS IAM roles, and on-prem AD groups are compliant with policies.
✅ Interview Summary You Can Speak:
“In this hybrid multi-cloud setup, Azure AD acts as the central IdP. Amit R authenticates once via Azure AD (MFA), receives ID Token, access token, and refresh token. Azure apps validate the tokens and enforce RBAC. AWS federates via SAML/OIDC; Azure AD issues assertions, AWS STS exchanges them for temporary credentials mapped to IAM roles. On-prem AD/LDAP is synced via Azure AD Connect; CBS validates local groups. Refresh tokens allow apps to get new access tokens without re-login, but authorization always happens locally. SailPoint governs provisioning and entitlement lifecycle across all clouds and on-prem.”
Sailpoint Integration
====
Absolutely — let’s integrate SailPoint into the multi-cloud token & access flow for Amit R. This will show provisioning, authentication, authorization, and governance end-to-end, including Azure, AWS, On-Prem, and SailPoint. I’ll keep it step-by-step and interview-ready.
Multi-Cloud AuthN/AuthZ Flow with SailPoint
Environment:
Azure (Region A) — apps, APIs
AWS (Region B) — analytics, microservices
On-Prem (Region C) — CBS, legacy apps
SailPoint — Identity Governance & Administration
Azure AD — Central IdP
User — Amit R
Phase 1 — Provisioning (Joiner / SailPoint)
HR creates Amit R in Workday (employee record: role = Relationship Manager).
Workday triggers SailPoint workflow (via connector / webhook).
SailPoint applies governance policies:
Checks SoD conflicts, regulatory access restrictions.
Determines required entitlements for Amit:
Azure AD groups: Lending_RM
AWS IAM roles: Loan_ReadOnly
On-Prem AD groups: CBS_ViewOnly
SailPoint provisions accounts & entitlements:
Azure AD: Creates user, assigns groups.
AWS: Sets up federation mapping to Azure AD groups → IAM roles.
On-Prem AD/LDAP: Adds Amit to required groups.
SailPoint logs all actions for audit & compliance.
Amit receives notification to set up MFA in Azure AD.
✅ Key Point: SailPoint is the central governance engine controlling entitlements across all environments.
Phase 2 — Authentication & Token Issuance (Azure AD as IdP)
Amit logs into Azure Lending App (Azure Region A).
App redirects Amit to Azure AD for authentication (OIDC flow).
Amit authenticates (password + MFA).
Azure AD issues tokens:
ID Token (OIDC) — contains identity claims and groups.
Access Token (OAuth2) — scopes for API access.
Refresh Token — long-lived token to get new access tokens.
Lending App validates tokens (signature, claims).
RBAC enforced using Azure AD group claims.
✅ SailPoint has already provisioned entitlements, so group claims are consistent with governance policies.
Phase 3 — Accessing AWS (Federated AuthN/AuthZ)
Amit accesses AWS Analytics App.
AWS app redirects Amit to Azure AD (federated IdP).
Azure AD issues SAML assertion / OIDC token with groups/roles.
AWS STS exchanges assertion for temporary IAM credentials mapped to entitlements provisioned by SailPoint.
Amit uses temporary creds to access AWS resources (S3, Redshift, etc.).
AWS IAM enforces local authorization policies based on the federated role.
Audit: AWS logs all actions with federated user info.
✅ SailPoint ensures requested roles comply with policies and SoD rules before they are federated.
Phase 4 — Accessing On-Prem (CBS / Legacy Apps)
Amit opens CBS portal.
Authentication options:
Azure AD SAML/OIDC federation if CBS supports it.
Otherwise, Amit’s Azure AD account was provisioned in On-Prem AD via SailPoint, so he can log in using AD credentials.
CBS maps AD group membership to application roles (LoanViewer, KYC_ReadOnly).
Authorization enforced locally; actions logged.
Network connectivity: ExpressRoute / private links ensures secure connection between cloud and on-prem.
✅ SailPoint governs group memberships, ensuring access aligns with policies.
Phase 5 — Token / Credential Flow Summary
Step | Token / Credential | Purpose | Validity |
1 | ID Token (OIDC) | Identify Amit to app | ~1h |
2 | Access Token (OAuth2) | Authorize API access | 15–60 min |
3 | Refresh Token | Get new access token without re-login | Days / weeks |
4 | AWS STS Temporary Credentials | Map federated identity to IAM role | 15–60 min |
5 | On-Prem AD credentials | Authenticate to CBS / LDAP apps | Managed by SailPoint |
✅ Key: SailPoint does not issue runtime tokens — it provisions and governs who can get which entitlements, ensuring tokens reflect policy.
Phase 6 — Lifecycle Management (Mover / Leaver)
Mover: Amit changes role → HR updates Workday → SailPoint updates:
Azure AD groups
AWS IAM role mappings
On-Prem AD groups
Leaver: Amit leaves → HR triggers SailPoint → deprovisions all accounts across clouds and on-prem.
Access Certification: Periodic review by managers; SailPoint automatically remediates policy violations.
Audit: All provisioning, access, token usage logged in SIEM.
Phase 7 — End-to-End Flow Diagram (Text Version)
[Workday HR]
│
▼
[SailPoint IGA] ──> Provision entitlements:
│ ├─> Azure AD groups
│ ├─> AWS IAM role mappings
│ └─> On-Prem AD groups
│
▼
[Amit R logs in]
│
▼
[Azure AD IdP]
│─> ID Token + Access Token + Refresh Token
│
▼
[Azure App] -- validate token & enforce RBAC
│
├────────> [AWS Apps] -- SAML/OIDC federation → AWS STS → temporary creds
│
└────────> [On-Prem CBS] -- AD creds / SAML token → authorization
[SailPoint] continuously audits & governs entitlements
[SIEM] collects logs across all environments
✅ Interview Key Talking Points
SailPoint is central governance layer: ensures entitlements comply with SoD, regulatory policies, and audits.
Azure AD is the single IdP: authentication, token issuance (OIDC / OAuth2 / Refresh).
Cloud-native authorization: AWS IAM and On-Prem AD enforce access locally.
Federation enables token reuse: AWS STS, SAML/OIDC allow multi-cloud trust.
Lifecycle events managed by SailPoint: onboarding, mover, leaver, certification.
Audit & compliance: all events logged in SIEM; policies enforced consistently.
End-to-End Multi-Cloud Authentication & Authorization Flow
Environment:
Azure (Region A) — Cloud-native apps (Lending App)
AWS (Region B) — Analytics / microservices
On-Prem (Region C) — CBS / legacy apps
SailPoint — Identity governance
Azure AD — Central IdP (Authentication Authority)
1️⃣ Phase 1 — Central User Provisioning
HR creates Amit R in Workday → triggers SailPoint workflow.
SailPoint:
Evaluates role (Relationship Manager) → determines entitlements for each system.
Provisions user in Azure AD → adds him to appropriate groups (Lending_RM).
Sets up AWS role mapping (Azure AD Group → AWS IAM role) and On-Prem AD group (CBS_ViewOnly).
Azure AD now becomes the single source of truth for authentication.
SailPoint governs entitlements and logs all provisioning actions for audit and compliance.
2️⃣ Phase 2 — User Authentication (Azure Apps)
Amit opens Azure Lending App.
App redirects Amit to Azure AD (IdP) for authentication.
Amit logs in:
Username/password
MFA (if enabled)
Azure AD issues tokens:
ID Token (OIDC) — JWT containing identity claims (name, email, groups)
Access Token (OAuth2) — JWT for API access
Refresh Token — allows apps to request new access tokens without re-login
Lending App validates token (signature & claims) → enforces authorization based on Azure AD group membership.
Amit can now access Azure-native resources securely.
3️⃣ Phase 3 — Accessing AWS Resources (Federation)
Amit clicks on AWS Analytics App.
App redirects Amit to Azure AD IdP (via OIDC / SAML federation).
Azure AD validates Amit’s identity (already authenticated, so SSO applies) and issues:
SAML assertion / OIDC token containing user identity and groups
AWS STS service receives the token and maps it to temporary IAM credentials:
Role mapping: Azure AD group Lending_RM → AWS IAM Role Loan_ReadOnly
Amit uses temporary credentials to access AWS resources (S3, Lambda, Redshift)
When credentials expire, Amit can use Azure AD refresh token to obtain new access tokens → STS temporary credentials renewed.
✅ Key Point: Authentication happens centrally in Azure AD, authorization is enforced locally via AWS IAM.
4️⃣ Phase 4 — Accessing On-Prem Resources
Amit opens CBS / On-Prem apps.
Authentication options:
SAML/OIDC federation: CBS app trusts Azure AD tokens directly.
On-Prem AD credentials: Azure AD accounts synced via Azure AD Connect or provisioned by SailPoint.
Authorization enforced by On-Prem AD groups (CBS_ViewOnly) mapped to app roles.
Secure connectivity:
Private network (VPN, ExpressRoute, DirectConnect) ensures secure access from cloud to on-prem.
All actions logged for audit & compliance.
5️⃣ Phase 5 — Token Usage Across Environments
Environment | Token Type | Issuer | Purpose | Usage |
Azure Apps | ID Token (OIDC) | Azure AD | Identify user | App validates JWT & extracts claims |
Access Token (OAuth2) | Azure AD | Authorize API calls | Sent in Authorization: Bearer header | |
Refresh Token | Azure AD | Renew access token | App calls Azure AD token endpoint | |
AWS | SAML Assertion / OIDC Token | Azure AD | Authenticate to AWS | Passed to STS for temporary IAM credentials |
Temporary IAM Credentials | AWS STS | Authorize AWS resources | Used to call AWS APIs / services | |
On-Prem | Azure AD token (if OIDC/SAML) | Azure AD | Authenticate user | App validates token & maps to AD group |
On-Prem AD credentials | On-Prem AD | Authorize access | App enforces role-based permissions |
6️⃣ Phase 6 — Lifecycle & Governance
Mover / Role Change: SailPoint updates Azure AD groups → AWS IAM mappings → On-Prem AD groups automatically.
Leaver: SailPoint deprovisions all accounts → access revoked across all environments.
Access Certification: Periodic review by managers via SailPoint.
Audit & Compliance: All token issuance, access events, and entitlement changes logged in SIEM.
7️⃣ Phase 7 — End-to-End Text Flow Diagram
[Workday HR]
│ create Amit R
▼
[SailPoint] ──> Provision & map entitlements:
│ ├─> Azure AD Group: Lending_RM
│ ├─> AWS Role Mapping: Loan_ReadOnly
│ └─> On-Prem AD Group: CBS_ViewOnly
│
▼
[Amit R logs in]
│
▼
[Azure AD IdP]
│ - Authenticates user (MFA)
│ - Issues: ID Token, Access Token, Refresh Token
│
▼
[Azure Apps] ← Validate token & enforce Azure RBAC
│
├──> [AWS Apps] ← SAML/OIDC token → AWS STS → temporary IAM credentials
│
└──> [On-Prem CBS] ← Azure AD token / AD credentials → local RBAC
[SailPoint] monitors all entitlements and updates mappings as needed
[SIEM] collects logs across all environments
✅ Key Talking Points for Interview
Azure AD is the central IdP → single authentication source across all environments.
Tokens issued by Azure AD:
ID Token → user identity
Access Token → API authorization
Refresh Token → renew access without login
AWS uses federation → Azure AD token mapped to temporary IAM credentials.
On-Prem uses synced credentials or federation → RBAC enforced locally.
SailPoint ensures governance → entitlements, SoD, audit logs.
Secure hybrid connectivity → VPN / private links between cloud & on-prem.
Lifecycle management is centralized via SailPoint → automated provisioning/deprovisioning.
1️⃣ Two Different Scenarios
Scenario A — Cloud-Native APIs in AWS (your Digital Lending example)
User-facing APIs: Frontend app calls AWS API Gateway → microservices in EKS
IdP: Azure AD (or Google, Okta, etc.)
Token flow:
User logs in → Azure AD issues ID token + OAuth2 access token + refresh token
Frontend app attaches access token as Bearer token in API calls
API Gateway & EKS microservices validate JWT access token
✅ No AWS STS token is needed here because microservices validate IdP-issued tokens directly.
This is the standard OAuth2 / OIDC JWT flow for user-facing API access.
Scenario B — Federated AWS Console / AWS Resources
User wants to access AWS-managed resources (S3, Redshift, Lambda) directly
IdP: Azure AD or another OIDC/SAML provider
Token flow:
User logs in → Azure AD issues token / SAML assertion
Token is sent to AWS STS (Security Token Service)
AWS STS issues temporary IAM credentials (access key, secret key, session token)
These temporary credentials are used to access AWS resources directly
✅ Needed because AWS does not natively accept IdP JWTs for resource access; it requires temporary IAM credentials.
2️⃣ Key Distinction
Use Case | Token Used | Issued By | Notes |
API Gateway / Microservices in AWS (user-facing) | OAuth2 JWT (Bearer) | Azure AD | APIs validate token directly. No AWS STS needed. |
Direct AWS resource access (S3, Redshift, Lambda) | Temporary AWS IAM creds | AWS STS | Azure AD token / SAML assertion exchanged for temporary credentials. |
✅ Summary:
JWT access tokens from Azure AD → good for API calls to your microservices in AWS.
AWS STS temporary tokens → only needed if user is accessing AWS-managed resources directly.
3️⃣ Interview-Friendly Explanation
“If Azure AD is the central IdP, it issues OAuth2 access tokens for authenticated users. For API calls to microservices deployed in AWS, these JWT tokens are used directly as bearer tokens. There is no need to call AWS STS in this case.AWS STS temporary credentials are only required when the user needs to access AWS-managed resources directly, like S3, Redshift, or Lambda, because AWS does not accept IdP-issued JWTs for native AWS resource access.”
To summarize in one line for interviews:
“JWT access tokens from Azure AD are used directly for API calls to microservices in AWS, while AWS STS temporary credentials are only needed for direct access to AWS-managed resources.”
=====
Microservices in AWS using a JWT to access AWS resources like S3. This is another subtle but important distinction between user authentication and service-to-AWS resource authorization. Let me explain step by step.
Scenario
User: Amit R
Frontend: Lending app
API / Microservice: Deployed in AWS EKS
User Access Token: JWT issued by Azure AD
AWS Resource: S3 bucket
1️⃣ JWT Access Token Validation
User calls AWS API Gateway / microservice with Bearer JWT token.
Microservice validates JWT:
Signature verified via Azure AD public keys (JWKS endpoint)
Token not expired
Claims verified (user ID, groups, roles)
If valid → microservice authorizes user to call its API
✅ So JWT is used only for user authentication / API authorization, not directly for S3 access.
2️⃣ Microservice Accessing AWS S3
AWS does not accept external JWTs for S3 access.
Microservice must use AWS credentials to access S3:
Option A — IAM Role for Service / Pod (recommended in EKS)
Assign an IAM Role to EKS Pod via IRSA (IAM Roles for Service Accounts)
Microservice assumes this role → gets temporary AWS credentials from STS
Uses these credentials to access S3 securely
Recommended approach: Use IAM Role for Service Account (IRSA):
Create an IAM Role with S3 access (upload/download permissions).
Associate the IAM Role with the EKS service account of the API pod.
AWS automatically provides temporary credentials (via STS behind the scenes).
API uses these temporary credentials to upload the document to S3.
Important: The user JWT is not passed to S3 and does not require calling STS directly.
The STS call is automatic when the EKS pod assumes the IAM Role — you don’t manually call STS.
Option B — Hardcoded IAM credentials (not recommended)
Microservice uses AWS access key/secret key to access S3
Option C — Centralized Token Exchange
Microservice exchanges Azure AD token for temporary AWS credentials via STS (less common for internal services)
✅ Best practice: Use IAM Roles for Service Accounts (IRSA). The user JWT is never sent to S3, only microservice uses its own IAM role.
3️⃣ End-to-End Flow
Amit → Azure AD → JWT Access Token
Amit → API Gateway / Microservice → validate JWT → authorize user
Microservice → assumes its EKS IAM role → temporary AWS credentials
Microservice → S3 → perform operations based on IAM role permissions
Key point:
User JWT = authorizes user to call microservice
Microservice IAM role = authorizes microservice to access AWS resources like S3
4️⃣ Explanation
“When a user calls an AWS-hosted microservice using a JWT access token issued by Azure AD, the token is only used to authenticate the user and authorize API access. If the microservice needs to access AWS resources like S3, it does so using an IAM Role attached to the EKS pod (IRSA) or temporary credentials, not the user JWT. This separates user authentication from service-level authorization, maintaining security and least privilege.”
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