Lambda Authorizer Overview

Deploy ASCEND governance to your AWS API Gateway with zero code changes using Lambda authorizers.

What is the ASCEND Lambda Authorizer?

The ASCEND Lambda Authorizer is a pre-built AWS Lambda function that integrates with API Gateway to provide real-time authorization decisions for AI agent API calls. Every request is evaluated against your organization's policies before reaching your backend services.

Architecture

                                    ASCEND Platform
                                          |
                                    (authorization)
                                          |
┌──────────┐    ┌─────────────┐    ┌──────────────┐    ┌──────────────┐
│ AI Agent │───>│ API Gateway │───>│ Lambda       │───>│ Backend      │
│          │    │             │    │ Authorizer   │    │ Service      │
└──────────┘    └─────────────┘    └──────────────┘    └──────────────┘
                                          │
                                    (Allow/Deny)

How It Works

1. AI agent makes request to API Gateway with agent headers
2. API Gateway invokes Lambda Authorizer before routing
3. Lambda Authorizer extracts agent info and calls ASCEND Platform
4. ASCEND Platform evaluates against policies and returns decision
5. Lambda generates IAM policy (Allow/Deny) for API Gateway
6. API Gateway routes request (if allowed) or returns 403

Key Features

Zero-Code Integration

Deploy as a Lambda function - no modifications to existing APIs required.

# API Gateway configuration
Type: AWS::ApiGateway::Authorizer
Properties:
  Name: AscendAuthorizer
  Type: REQUEST
  AuthorizerUri: !Sub arn:aws:apigateway:${AWS::Region}:lambda:path/2015-03-31/functions/${AscendAuthorizerArn}/invocations

Fail-Secure Design

All errors result in DENY responses - following security best practices.

# From handler.py
def lambda_handler(event, context):
    try:
        # Evaluate with ASCEND
        decision = ascend.evaluate(...)
    except Exception:
        # FAIL SECURE: deny on any error
        return generate_deny_policy()

Response Caching

Configurable caching reduces latency for repeated requests:

Setting	Description	Default
Cache TTL	How long to cache decisions	60 seconds
Cache Key	What uniquely identifies a request	Agent ID + Action
Cache Approved Only	Only cache approved decisions	Yes

Full Observability

• CloudWatch Metrics: Decisions, latency, errors
• CloudWatch Logs: Structured JSON logging
• X-Ray Tracing: End-to-end request tracing
• CloudWatch Dashboard: Pre-built monitoring dashboard

Request Headers

AI agents must include these headers in requests:

Header	Required	Description
X-Ascend-Agent-Id	Yes	Unique agent identifier
X-Ascend-Environment	No	Environment (production/staging/dev)
X-Ascend-Data-Sensitivity	No	Data sensitivity level
X-Ascend-Tool-Name	No	Tool/capability being used
X-Ascend-Target-System	No	Target resource identifier

Example Request

curl -X POST https://api.example.com/data \
  -H "X-Ascend-Agent-Id: my-ai-agent" \
  -H "X-Ascend-Environment: production" \
  -H "X-Ascend-Tool-Name: database.query" \
  -H "Content-Type: application/json" \
  -d '{"query": "SELECT * FROM customers"}'

Response Context

The authorizer adds context to approved requests via API Gateway:

{
  "requestContext": {
    "authorizer": {
      "ascendActionId": "act_abc123",
      "ascendAgentId": "my-ai-agent",
      "ascendRiskScore": 35,
      "ascendRiskLevel": "low",
      "ascendEnvironment": "production"
    }
  }
}

Your backend can access this context for additional processing.

Decision Logic

The authorizer uses this decision logic:

ASCEND Status	Lambda Response	Result
approved	Allow	Request proceeds
pending_approval	Deny	Request blocked (needs human review)
denied	Deny	Request blocked (policy violation)
Any error	Deny	Request blocked (fail-secure)

Configuration Options

Environment Variables

Variable	Description	Default
ASCEND_API_URL	ASCEND Platform API URL	Required
ASCEND_API_KEY	API key for authentication	Required
ASCEND_API_KEY_SECRET_ARN	Secrets Manager ARN (preferred)	None
ASCEND_ENVIRONMENT	Environment context	production
ASCEND_CACHE_TTL	Cache TTL in seconds	60
ASCEND_TIMEOUT	API timeout in seconds	4
LOG_LEVEL	Logging level	INFO

CloudFormation Parameters

Parameters:
  AscendApiUrl:
    Type: String
    Default: https://api.ascend.owkai.app

  AscendApiKeySecret:
    Type: String
    Description: ARN of Secrets Manager secret

  Environment:
    Type: String
    Default: production
    AllowedValues:
      - production
      - staging
      - development

  CacheTtlSeconds:
    Type: Number
    Default: 60
    MinValue: 0
    MaxValue: 300

Performance

The Lambda Authorizer is optimized for low latency:

Metric	Target	Typical
Cold start	< 500ms	~200ms
Warm invocation	< 100ms	~50ms
Cache hit	< 10ms	~5ms
P99 latency	< 100ms	~75ms

Optimization Tips

1. Use Provisioned Concurrency - Eliminates cold starts
2. Enable Response Caching - Reduces ASCEND API calls
3. Use ARM64 Architecture - Better price/performance
4. Deploy in Same Region - Minimize network latency

Security

API Key Storage

Store API keys in AWS Secrets Manager:

aws secretsmanager create-secret \
  --name ascend/api-key \
  --secret-string '{"api_key":"owkai_prod_xxxx"}'

IAM Permissions

Minimum required permissions:

- Effect: Allow
  Action:
    - secretsmanager:GetSecretValue
  Resource: !Ref AscendApiKeySecret

- Effect: Allow
  Action:
    - logs:CreateLogStream
    - logs:PutLogEvents
  Resource: !Sub 'arn:aws:logs:${AWS::Region}:${AWS::AccountId}:log-group:/aws/lambda/ascend-authorizer-*'

VPC Deployment

For private API endpoints, deploy Lambda in VPC:

VpcConfig:
  SecurityGroupIds:
    - !Ref AuthorizerSecurityGroup
  SubnetIds:
    - !Ref PrivateSubnet1
    - !Ref PrivateSubnet2

Compliance

The Lambda Authorizer supports compliance requirements:

Standard	Control	Implementation
SOC 2	CC6.1	All requests logged and audited
HIPAA	164.312(d)	Access control enforcement
PCI-DSS	7.1	Least privilege authorization
NIST	AC-3	Access enforcement

Troubleshooting

Common Issues

403 Forbidden on all requests:

1. Check API key is valid
2. Verify agent ID header is present
3. Check CloudWatch logs for errors

High latency:

1. Enable response caching
2. Check network connectivity to ASCEND
3. Consider provisioned concurrency

Cache not working:

1. Verify cache TTL > 0
2. Check cache key matches request pattern
3. Ensure approved decisions only

Debug Mode

Enable debug logging for troubleshooting:

LOG_LEVEL: DEBUG

View logs in CloudWatch:

aws logs tail /aws/lambda/ascend-authorizer-production --follow

Next Steps

• Deployment Guide - Deploy with SAM/CloudFormation
• Python SDK - Client-side integration
• API Reference - Direct API usage

Support

• Documentation: https://docs.owkai.app
• Support: support@owkai.app
• GitHub Issues: https://github.com/owkai/ascend-lambda-authorizer/issues