OAuth Token Propagation Patterns
# OAuth Token Propagation Patterns in Microservices
## 1. Token Relay Pattern
### Description
Forwards the original OAuth token through service chains while maintaining the original user context.
### Implementation
```mermaid
sequenceDiagram
participant C as Client
participant AG as API Gateway
participant S1 as Service 1
participant S2 as Service 2
C->>AG: Request + OAuth Token
AG->>AG: Validate Token
AG->>S1: Forward Request + Token
S1->>S2: Forward Request + Original Token
S2->>S2: Validate Token
```
### Considerations
- **Pros:**
- Simple implementation
- Maintains user context
- Easy to audit
- **Cons:**
- Token size overhead
- Potential scope exposure
- Limited granular control
### Code Example
```java
public class TokenRelayInterceptor implements ClientHttpRequestInterceptor {
@Override
public ClientHttpResponse intercept(HttpRequest request, byte[] body,
ClientHttpRequestExecution execution) {
String token = SecurityContextHolder.getContext()
.getAuthentication()
.getCredentials()
.toString();
request.getHeaders().add("Authorization", "Bearer " + token);
request.getHeaders().add("X-Original-User-Context", getUserContext());
return execution.execute(request, body);
}
}
```
## 2. Token Exchange Pattern
### Description
Exchanges the original token for service-specific tokens with limited scope.
### Implementation
```mermaid
sequenceDiagram
participant C as Client
participant AG as API Gateway
participant STS as Security Token Service
participant S1 as Service 1
participant S2 as Service 2
C->>AG: Request + OAuth Token
AG->>STS: Exchange Token Request
STS->>AG: Service-Specific Token
AG->>S1: Request + New Token
S1->>STS: Exchange Token
STS->>S1: Service-Specific Token
S1->>S2: Request + New Token
```
### Considerations
- **Pros:**
- Fine-grained access control
- Reduced token size
- Better security isolation
- **Cons:**
- Additional complexity
- Higher latency
- More infrastructure needed
### Code Example
```java
public class TokenExchangeService {
public String exchangeToken(String originalToken, String targetService) {
TokenExchangeRequest request = TokenExchangeRequest.builder()
.subjectToken(originalToken)
.targetService(targetService)
.build();
return securityTokenService.exchange(request);
}
}
```
## 3. Token Cache Pattern
### Description
Implements caching mechanisms for token validation and exchange results.
### Implementation
```mermaid
sequenceDiagram
participant S as Service
participant C as Cache
participant V as Token Validator
S->>C: Check Token
alt Token in Cache
C->>S: Return Cached Result
else Token Not in Cache
C->>V: Validate Token
V->>C: Store Result
C->>S: Return Result
end
```
### Code Example
```java
public class TokenValidationCache {
private Cache<String, TokenValidation> validationCache;
public TokenValidation validateToken(String token) {
return validationCache.get(token, key -> {
TokenValidation validation = tokenValidator.validate(key);
if (validation.isValid()) {
validationCache.put(key, validation,
validation.getTimeToLive());
}
return validation;
});
}
}
```
## 4. Circuit Breaker Pattern
### Description
Implements failure handling for token validation and exchange services.
### Implementation
```mermaid
sequenceDiagram
participant S as Service
participant CB as Circuit Breaker
participant TS as Token Service
S->>CB: Token Request
alt Circuit Closed
CB->>TS: Forward Request
TS->>CB: Response
CB->>S: Return Response
else Circuit Open
CB->>S: Return Fallback
end
```
### Code Example
```java
public class TokenServiceCircuitBreaker {
private CircuitBreaker circuitBreaker;
public TokenValidation validateWithCircuitBreaker(String token) {
return circuitBreaker.run(
() -> tokenService.validate(token),
throwable -> handleFailure(token)
);
}
private TokenValidation handleFailure(String token) {
// Implement fallback strategy
return TokenValidation.fallback(token);
}
}
```
## 5. Decorator Pattern for Token Enhancement
### Description
Adds additional context or claims to tokens as they pass through services.
### Implementation
```mermaid
sequenceDiagram
participant S1 as Service 1
participant TD as Token Decorator
participant S2 as Service 2
S1->>TD: Original Token
TD->>TD: Add Context
TD->>S2: Enhanced Token
```
### Code Example
```java
public class TokenEnhancerDecorator implements TokenEnhancer {
private final TokenEnhancer delegate;
public OAuth2AccessToken enhance(OAuth2AccessToken token,
OAuth2Authentication auth) {
token = delegate.enhance(token, auth);
Map<String, Object> additionalInfo = new HashMap<>();
additionalInfo.put("service_context", getServiceContext());
((DefaultOAuth2AccessToken) token)
.setAdditionalInformation(additionalInfo);
return token;
}
}
```
## 6. Observer Pattern for Token Events
### Description
Implements event-based handling of token lifecycle events.
### Implementation
```mermaid
sequenceDiagram
participant TS as Token Service
participant P as Publisher
participant S1 as Subscriber 1
participant S2 as Subscriber 2
TS->>P: Token Event
P->>S1: Notify
P->>S2: Notify
```
### Code Example
```java
public class TokenEventPublisher {
private List<TokenEventSubscriber> subscribers = new ArrayList<>();
public void publishTokenEvent(TokenEvent event) {
for (TokenEventSubscriber subscriber : subscribers) {
subscriber.onTokenEvent(event);
}
}
public void subscribe(TokenEventSubscriber subscriber) {
subscribers.add(subscriber);
}
}
```
## Best Practices for Pattern Implementation
1. **Combination of Patterns**
- Use Token Relay for simple flows
- Implement Token Exchange for complex scenarios
- Always include Circuit Breaker for resilience
- Cache validation results where appropriate
2. **Security Considerations**
- Implement proper token validation at each service
- Use secure communication channels
- Implement proper logging and monitoring
- Regular security audits
3. **Performance Optimization**
- Implement efficient caching strategies
- Use asynchronous token validation where possible
- Optimize token size and content
- Implement proper timeout handling
4. **Monitoring and Maintenance**
- Monitor pattern effectiveness
- Regular pattern review and updates
- Implement proper logging
- Set up alerts for pattern failures
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