Zipkin Instrumentation for Express

Installation

npm add express-zipkin-instrumentation --save;

Usage

Basic

const server = express();
// ...
const expressZipkinInstrumentation = require('express-zipkin-instrumentation');
server.use(expressZipkinInstrumentation(
  'service-name',
  'http://zipkin.yourdomain.com',
));

The above will result in a service identified in the Zipkin dashboard as service-name.

Complete

const server = express();
// ...
const expressZipkinInstrumentation = require('express-zipkin-instrumentation');
server.use(expressZipkinInstrumentation(
  'service-name',
  'http://zipkin.yourdomain.com',
  {
    serviceNamePostfix: 'development'
  }
))

The above will result in a service identified in the Zipkin dashboard as service-name-development.

The API

.constructor()

Using the following to include the package:

const expressZipkinInstrumentation = require('express-zipkin-instrumentation');

The expressZipkinInstrumentation variable will be a function that returns the correct middleware. The arguments are:

• :serviceName
  • identifies the current application in the zipkin dashboard.
• :zipkinHostname
  • the hostname for the zipkin server. When this is set to null (the default behaviour if this is not specified), the trace logs will be routed to stdout instead via console.trace.
• :options (optional)
  • an object that can contain the following properties:
    • :serviceNamePostfix: this will be appended to the :serviceName parameter in dashed-case.

const expressZipkinInstrumentation = require('express-zipkin-instrumentation');
const server = require('express')();
server.use(expressZipkinInstrumentation(/* ... */));
// ...

.getContext()

Retrieves the context used to initialise the zipkin instrumentation.

const expressZipkinInstrumentation = require('express-zipkin-instrumentation');
const server = require('express')();
server.use(expressZipkinInstrumentation(/* ... */));
expressZipkinInstrumentation.getContext();
// ...

.getInstance()

Retrieves the zipkin instrumentation instance.

const expressZipkinInstrumentation = require('express-zipkin-instrumentation');
const server = require('express')();
server.use(expressZipkinInstrumentation(/* ... */));
expressZipkinInstrumentation.getInstance();
// ...

.getParentId()

Retrieves the parent trace ID of the current request.

const expressZipkinInstrumentation = require('express-zipkin-instrumentation');
const server = require('express')();
server.use(expressZipkinInstrumentation(/* ... */));
server.use((req, res, next) => {
  console.info(expressZipkinInstrumentation.getParentId()); // matches /[0-9a-f]{16}/gi
  next();
});
// ...

Throws an error if expressZipkinInstrumentation(/* ... */) was not called yet.

.getRecorder()

Retrieves the recorder used to initialise the zipkin instrumentation.

const expressZipkinInstrumentation = require('express-zipkin-instrumentation');
const server = require('express')();
server.use(expressZipkinInstrumentation(/* ... */));
expressZipkinInstrumentation.getRecorder();
// ...

.getSpanId()

Retrieves the span ID of the current request.

const expressZipkinInstrumentation = require('express-zipkin-instrumentation');
const server = require('express')();
server.use(expressZipkinInstrumentation(/* ... */));
server.use((req, res, next) => {
  console.info(expressZipkinInstrumentation.getSpanId()); // matches /[0-9a-f]{16}/gi
  next();
});
// ...

Throws an error if expressZipkinInstrumentation(/* ... */) was not called yet.

.getTraceId()

Retrieves the trace ID of the current request.

const expressZipkinInstrumentation = require('express-zipkin-instrumentation');
const server = require('express')();
server.use(expressZipkinInstrumentation(/* ... */));
server.use((req, res, next) => {
  console.info(expressZipkinInstrumentation.getTraceId()); // matches /[0-9a-f]{16}/gi
  next();
});
// ...

Throws an error if expressZipkinInstrumentation(/* ... */) was not called yet.

Development

Testing

Run tests using:

npm run test

To run them in watch mode:

npm run test-watch

Continuous Integration

Environment Variables

The following environment variables have to be set in Travis for the pipeline to work

• GH_USERNAME: GitHub username
• GH_ACCESS_TOKEN: GitHub personal access token
• NPM_PACKAGE_PUBLISH_NAME: Package name to publish this as
• NPM_REGISTRY_URL: Hostname of NPM registry being used
• NPM_TOKEN: NPM access token
• GIT_ORIGIN_REMOTE_PATH: Path to repository in GitHub

License

This package is licensed under the MIT license.