Node.js

What does it do

As an asynchronous event-driven JavaScript runtime, Node.js is designed to build scalable network applications. In Node.js, many connections can be handled concurrently. Upon each connection, the callback is fired, but if there is no work to be done, Node.js will sleep.

HTTP is a first-class citizen in Node.js, designed with streaming and low latency in mind. This makes Node.js well-suited for the foundation of a web library or framework.

Node.js Request Flow

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Node.js Contract

The following defines the requirements to run the Node.js module in the Section platform:

Essential

  • HTTP server listening a port defined by process.env.PORT for HTTP/1.1 — never using HTTPS or any other port.
  • In the event communicating upstream or to another service you must connect to next-hop:80 as HTTP, never HTTPS.
    • The platform will ensure next-hop resolves to the next proxy in the chain or the origin — whichever is next upstream.
    • Specify a X-Forwarded-Proto: https HTTP request header to perform HTTPS requests to the origin.
  • Proxy must handle logs according to these requirements:
    • All log files must be written under the /var/log/nodejs directory.
  • Your config must contain a .gitignore file which ignores the node_modules directory.
  • Your Node.js config must contain a package-lock.jsonfile which is generated by npm.
  • Your Node.js application must contain a npm start script which must start your HTTP server.
  • Note: You must use npm as yarn is unsupported for now.

Optional

  • Your application should handle run time errors which does not crash the application.

Things you can rely on

  • Module can expect a X-Forwarded-Proto: https request header for HTTPS connections from the browser. Assume HTTP otherwise.
  • Module can expect a True-Client-IP request header containing the IP address of the client connecting to the Section servers. The X-Forwarded-For request header will be also be present but may contain multiple IP addresses from other HTTP proxies between the client and the Node.js module.