Micronaut Security Interview Questions and Answers
Master Micronaut Security with interview questions covering authentication, authorization, JWT, OAuth2, role-based access control, security filters, HTTPS, and production security best practices.
Micronaut Security Interview Questions and Answers
Introduction
Security is one of the most critical aspects of enterprise applications. Every request reaching a Micronaut application should be authenticated, authorized, validated, and protected against common attacks.
Micronaut Security provides built-in support for:
- Authentication
- Authorization
- JWT Authentication
- OAuth2/OpenID Connect
- Role-Based Access Control (RBAC)
- Security Filters
- HTTPS
- Token Validation
Micronaut Security is designed for cloud-native applications and integrates seamlessly with identity providers such as Keycloak, Okta, Azure AD, Auth0, Google, and AWS Cognito.
Micronaut Security Architecture
flowchart LR
Client --> SecurityFilter
SecurityFilter --> Authentication
Authentication --> Authorization
Authorization --> Controller
Controller --> Service
Service --> Database
Q1. What is Micronaut Security?
Answer
Micronaut Security is a framework module that secures REST APIs and microservices.
It provides:
- Authentication
- Authorization
- JWT Validation
- OAuth2 Login
- Session Security
- Role-Based Access Control
Benefits
- Lightweight
- Cloud Native
- Stateless Authentication
- Easy JWT Integration
- High Performance
Q2. What is Authentication?
Authentication verifies who the user is.
Examples
- Username & Password
- JWT Token
- OAuth Login
- LDAP
- API Key
Example Request
POST /login
Credentials
{
"username":"venu",
"password":"password"
}
Server Response
JWT Token
Q3. What is Authorization?
Authorization determines what an authenticated user is allowed to access.
Example
@Secured("ROLE_ADMIN")
@Controller("/admin")
public class AdminController {
}
Flow
flowchart TD
User --> Login
Login --> JWT
JWT --> Authorization
Authorization --> Controller
Only users with the required role can access the endpoint.
Q4. What is JWT Authentication?
JWT (JSON Web Token) is a stateless authentication mechanism.
Flow
sequenceDiagram
Client->>Server: Login
Server-->>Client: JWT Token
Client->>Server: Request + JWT
Server->>JWT Validator: Verify
JWT Validator-->>Server: Valid
Server-->>Client: Response
Authorization Header
Authorization:
Bearer eyJhbGci...
Advantages
- Stateless
- Scalable
- No server session
- Ideal for microservices
Q5. How do you secure Controllers?
Micronaut uses the @Secured annotation.
Example
@Secured(SecurityRule.IS_AUTHENTICATED)
@Controller("/customers")
public class CustomerController {
}
Public endpoint
@Secured(SecurityRule.IS_ANONYMOUS)
Admin endpoint
@Secured("ROLE_ADMIN")
Q6. What is OAuth2?
OAuth2 allows authentication using external identity providers.
Examples
- GitHub
- Azure AD
- Okta
- Keycloak
Architecture
flowchart LR
User --> Google
Google --> JWT
JWT --> Micronaut
Micronaut --> Application
Benefits
- Single Sign-On (SSO)
- Enterprise Identity
- Reduced password management
Q7. What is Role-Based Access Control (RBAC)?
RBAC restricts access based on user roles.
Example
| Role | Access |
|---|---|
| USER | View Profile |
| ADMIN | Manage Users |
| MANAGER | Approvals |
| AUDITOR | Reports |
Controller
@Secured({
"ROLE_ADMIN",
"ROLE_MANAGER"
})
Q8. What is the Security Filter?
Every request first passes through the Security Filter.
Flow
flowchart LR
HTTPRequest --> SecurityFilter
SecurityFilter --> JWTValidation
JWTValidation --> Authorization
Authorization --> Controller
Responsibilities
- Read token
- Validate token
- Load user
- Check roles
- Reject unauthorized requests
Q9. How is Security implemented in Production?
Enterprise architecture
flowchart TD
Client --> ApiGateway["API Gateway"]
ApiGateway["API Gateway"] --> OauthServer["OAuth Server"]
OauthServer["OAuth Server"] --> JWT
JWT --> Micronaut
Micronaut --> Database
Micronaut --> Kafka
Micronaut --> Audit
Production recommendations
- HTTPS
- OAuth2
- JWT
- API Gateway
- Secret Manager
- Token Expiration
- Audit Logging
Q10. Security Best Practices
Always Use HTTPS
Never transmit tokens over HTTP.
Use JWT
Avoid session-based authentication for microservices.
Keep Tokens Short-Lived
Use refresh tokens when required.
Store Secrets Securely
Use
- Vault
- AWS Secrets Manager
- Azure Key Vault
- Kubernetes Secrets
Validate Every Request
Never trust client input.
Banking Example
flowchart TD
MobileApp --> ApiGateway["API Gateway"]
ApiGateway["API Gateway"] --> JwtValidation["JWT Validation"]
JwtValidation["JWT Validation"] --> TransferApi["Transfer API"]
TransferApi["Transfer API"] --> FraudService["Fraud Service"]
TransferApi["Transfer API"] --> Database
TransferApi["Transfer API"] --> AuditService["Audit Service"]
Every request is authenticated, authorized, audited, and validated before processing.
Common Interview Questions
- What is Micronaut Security?
- Authentication vs Authorization?
- What is JWT?
- How does OAuth2 work?
- What is RBAC?
- What is
@Secured? - Explain Security Filters.
- Why use HTTPS?
- How do you secure REST APIs?
- Security best practices?
Quick Revision
| Topic | Summary |
|---|---|
| Authentication | Verify identity |
| Authorization | Verify permissions |
| JWT | Stateless authentication |
| OAuth2 | Third-party authentication |
| RBAC | Role-based authorization |
| @Secured | Secure endpoints |
| Security Filter | Validates requests |
| HTTPS | Encrypt communication |
| API Gateway | Entry point security |
| Audit | Track user actions |
Security Request Lifecycle
sequenceDiagram
Client->>API Gateway: HTTP Request
API Gateway->>Security Filter: Forward Request
Security Filter->>JWT Validator: Validate Token
JWT Validator-->>Security Filter: Valid User
Security Filter->>Controller: Authorized Request
Controller->>Service: Business Logic
Service-->>Controller: Response
Controller-->>Client: JSON Response
Key Takeaways
- Micronaut Security provides built-in support for authentication, authorization, JWT, OAuth2, RBAC, and security filters.
- Authentication verifies the user's identity, while authorization determines what the user is allowed to access.
- JWT enables stateless authentication, making it ideal for cloud-native microservices.
- Use
@Securedto protect controllers and endpoints based on authentication status or user roles. - OAuth2 integration allows authentication through providers such as Google, GitHub, Azure AD, Okta, and Keycloak.
- Every incoming request passes through a Security Filter for token validation and authorization checks.
- Always use HTTPS to encrypt communication between clients and services.
- Store credentials and secrets in secure external systems instead of application source code.
- Keep JWT access tokens short-lived and implement refresh tokens where appropriate.
- Secure, scalable enterprise applications combine JWT, RBAC, HTTPS, API Gateways, auditing, and centralized identity providers.