Correlation Id

How to use

Create correlation id instance

const {createCorrelationId} = require(`@vizydrop/correlation-id`);
const correlationId = createCorrelationId();

Integrate with @vizydrop/logger

const {createLogger} = require(`@vizydrop/logger`);

const logger = createLogger({
    correlationId: {
        enabled: true,
        getCorrelationId: () => correlationId.correlator.getId(),
        emptyValue: `nocorrelation`,
    },
});

Register middleware. Support koa and express

// koa
app.use(correlationId.koaMiddleware);
// express
app.use(correlationId.expressMiddleware);

Enhance request so each request will contain correlation id http header.

const request = require(`request`);
const correlatedRequest = correlationId.enhanceRequest(request);
correlatedRequest.get(`http://anotherservice:10020/data`);

Enhance http proxy so each proxied request will contain correlation id http header.

const httpProxy = require(`http-proxy`);
const proxy = httpProxy.createProxyServer({target: `http://anotherservice:10020/`});
correlationId.enhanceHttpProxy(proxy);

Run jobs. Jobs usually do not go through express/koa middleware so correlation id should be generated manually.

function jobTask() {}

function runJob() {
    correlationId.correlator.withId(correlator.generateDefaultId(), () => {
        jobTask();
    });
}

Settings

Custom settings can be passed as an object to createCorrelationId function.

• generateDefaultId - function that should return new correlation id. By default uuid is used.
• namespaceName - namespace for cls hook. Default value is correlation-id-namespace
• httpHeaderParamName - name of http header that contains correlation id value. Default value is x-correlationid

Correlation ID API

• expressMiddleware - express middleware that runs next middlewares in scope of correlation id async hook
• koaMiddleware - koa middleware that runs next middlewares in scope of correlation id async hook
• enhanceHttpRequest - takes request and return new request instance that adds correlation id header by default
• enhanceHttpProxy - register additional listener that adds correlation id header by default
• correlator.getId() - returns current correlation id
• correlator.withId(id, fn) - run function and all subsequent function with specified correlation id
• correlator.bindEmitter() - see https://github.com/jeff-lewis/cls-hooked#namespacebindemitteremitter
• correlator.bind() - see https://github.com/jeff-lewis/cls-hooked#namespacebindemitteremitter
• correlator.generateId() - generates new correlation id

Known issues

• does not work well with bluebird.promisifyAll. Alternative solution is to explicitly promisify using native promise

const redis = require(`redis`);
const util = require(`util`);

const client = redis.createClient();

client.setAsync = util.promisify(client.set).bind(client);
client.getAsync = util.promisify(client.get).bind(client);

• does not work well with mongoose callbacks. Alternative solution is to use promisified functions.

const mongoose = require(`mongooose`);
mongoose.Promise = global.Promise;

EntityModel.find({name: `name`}).then((value) => {
    // do something
});