nanonode-express

A tiny and very opinionated nanoservices framework inspired by expressjs.

This is library to host all the common and boring features shared between our nanoservices.

WARNING: This library is a work in progress and isn't intended to be general purpose.

Things like:

• logging
• basic error handling
• metrics
• health checks
• tracing requests and events across services

Installation

npm install --save nanonode-express

Example Usage (TypeScript)

import * nano from 'nanonode-express';

//
// Entry point for the nanoservice.
// The 'export' keyword is for testing.
//
export async function main(service: INanoService): Promise<void> {

    //
    // Handle a message, do some work, then publish a new message.
    // This uses Rabbitmq under the hood for reliable message handling.
    // The callback is wrapped for error handling, performance metrics and message tracing.
    // A bit like Express's post function.
    //
    service.on("do-some-work", async (args, res) => {
        //
        // ... do some work ...
        //

        //
        // Emit an outgoing event.
        //
        await service.emit("another-event", { your: "json data goes here" });

        //
        // Acknowledge that the message was handled correctly.
        //
        await res.ack();
    });

    //
    // Create a HTTP GET request handler for a particular route.
    // Do some work and return some json.
    // Under the hood this is handled by Express, but the callback is wrapped for
    // error handling, performance metrics and request tracing.
    //
    service.get('/another-end-point', async (req, res) => {
        //
        // ... do some work ...
        //

        //
        // Respond to the request with some JSON data.
        //
        await res.json({
            your: "json data"
        });
    });

    //
    // End points can be easily forwarded to internal services.
    //
    service.get('/another-end-point', async (req, res) => {
        //
        // Proxy the request to 'another-service'.
        //
        service.forwardRequest("another-service", "/a-different-end-point", { optionalQueryParameters: "go here" }, res);
    });

    //
    // Initiate the service (a bit like like Express' listen function).
    //
    await service.start();

}

if (require.main === module) {


    //
    // Run nano service as normal.
    //
    const service = nano();

    main(service)
        .then(() => logger.info("Online"))
        .catch(err => {
            console.error("Failed to start!");
            console.error(err && err.stack || err);
        });
}
else {
    //
    // Don't start nanoservice, this allows the service to be loaded for unit testing.
    //
}

Building the code

Open folder in Visual Studio Code and hit Ctrl+Shift+B

Or

npm build

Or

npx tsc [-w]

Tests

npm test

Or

npm run test:watch

Or

npx mocha --opts ./src/test/mocha.opts

Or

npx mocha --watch --watch-extensions ts --opts ./src/test/mocha.opts

Debugging

Debugging the command line app

• Open in Visual Studio Code.
• Select 'Main' debug configuration.
• Set your breakpoints.
• Hit F5 to run.

Debugging the tests

• Open in Visual Studio Code.
• Select 'Mocha' debug configuration.
• Open the test source file to execute.
• Set your breakpoints.
• Hit F5 to run.