How to Mock Canary Deployment Traffic Split in Python

class CanaryDeployment:
    def __init__(self, stable_weight: float = 0.9, canary_weight: float = 0.1):
        self.stable_weight = stable_weight
        self.canary_weight = canary_weight
        self.total_weight = stable_weight + canary_weight

    def route_request(self, request_id: int) -> str:
        """Route a request to stable or canary based on deterministic hash."""
        # Simple hash to distribute traffic deterministically
        hash_value = (request_id * 2654435761) % 1000
        threshold = (self.stable_weight / self.total_weight) * 1000
        return "stable" if hash_value < threshold else "canary"


def simulate_traffic(deployment: CanaryDeployment, num_requests: int = 1000) -> dict:
    """Simulate traffic distribution and report stats."""
    routing_results = {"stable": 0, "canary": 0}

    for request_id in range(num_requests):
        target = deployment.route_request(request_id)
        routing_results[target] += 1

    return routing_results


if __name__ == "__main__":
    deploy = CanaryDeployment(stable_weight=0.8, canary_weight=0.2)
    stats = simulate_traffic(deploy, num_requests=1000)

    print(f"Simulated 1000 requests with 80/20 split:")
    print(f"  -> Stable: {stats['stable']} ({stats['stable']/10:.1f}%)")
    print(f"  -> Canary: {stats['canary']} ({stats['canary']/10:.1f}%)")
    print(f"  -> Sample route for request #42: {deploy.route_request(42)}")