gRPC

duck_net supports gRPC unary calls and server reflection for service discovery. Protobuf messages are passed as JSON and automatically encoded/decoded.

Functions

Function	Parameters	Returns
grpc_call	(url, service, method, json_payload)	STRUCT(success BOOLEAN, status_code INTEGER, body VARCHAR, grpc_status INTEGER, grpc_message VARCHAR)
grpc_list_services	(url)	STRUCT(success BOOLEAN, services VARCHAR[], message VARCHAR)

Unary Calls

Pass the service name, method, and a JSON-encoded request body:

-- Call a gRPC method
SELECT (grpc_call(
    'https://grpc.example.com:443',
    'myapp.UserService',
    'GetUser',
    '{"user_id": 42}'
)).body;

The body field contains the JSON-decoded protobuf response. The grpc_status field contains the gRPC status code (0 = OK).

-- Check for errors
SELECT
    r.success,
    r.grpc_status,
    r.grpc_message,
    r.body
FROM (
    SELECT grpc_call(
        'https://grpc.example.com:443',
        'myapp.UserService',
        'GetUser',
        '{"user_id": 42}'
    ) AS r
);

Service Reflection

Discover available services on a gRPC server that has reflection enabled:

SELECT (grpc_list_services('https://grpc.example.com:443')).services;

Security Considerations

• gRPC endpoints are validated against SSRF rules.
• Responses are capped at 16 MiB to prevent memory exhaustion.
• Protobuf deserialization enforces recursion depth limits to prevent stack overflow.
• Use the grpc secret type for token-based authentication.
• Only TLS (https://) connections are supported in production; plaintext triggers a warning.