@pionerlabs/grpc-interceptors/utils.js

This library provides a way to instrument Node.js gRPC clients and servers with interceptors/middleware e.g. for Prometheus metrics, Zipkin tracing etc.

const getType = method => {
    if (method.requestStream === false && method.responseStream === false) {
        return 'unary';
    }
    return 'unknown';
};

const toLowerCamelCase = str => {
    return str.charAt(0).toLowerCase() + str.slice(1);
};

const getAllPropertyNames = (obj) => {
    var props = [];
    do {
        props= props.concat(Object.getOwnPropertyNames(obj ));
    } while (obj = Object.getPrototypeOf(obj));
    return props;
};

const lookupServiceMetadata = (service, implementation) => {
    const serviceKeys = Object.keys(service);
    const implementationKeys = getAllPropertyNames(implementation);
    const intersectingMethods = serviceKeys
        .filter(k => {
            return implementationKeys.map(k => toLowerCamelCase(k)).indexOf(k) !== -1;
        })
        .reduce((acc, k) => {
            const method = service[k];
            if (!method) {
                throw new Error(`cannot find method ${k} on service`);
            }
            const components = method.path.split('/');
            acc[k] = {
                name: components[1],
                method: components[2],
                type: getType(method),
                path: method.path,
                responseType: method.responseType,
                requestType: method.requestType,
            };
            return acc;
        }, {});

    return key => {
        return Object.keys(intersectingMethods)
            .filter(k => toLowerCamelCase(key) === k)
            .map(k => intersectingMethods[k]).pop();
    };
};

module.exports = {
    lookupServiceMetadata,
};