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)

1import * nano from 'nanonode-express';
2
3//
4// Entry point for the nanoservice.
5// The 'export' keyword is for testing.
6//
7export async function main(service: INanoService): Promise<void> {
8
9    //
10    // Handle a message, do some work, then publish a new message.
11    // This uses Rabbitmq under the hood for reliable message handling.
12    // The callback is wrapped for error handling, performance metrics and message tracing.
13    // A bit like Express's post function.
14    //
15    service.on("do-some-work", async (args, res) => {
16        //
17        // ... do some work ...
18        //
19
20        //
21        // Emit an outgoing event.
22        //
23        await service.emit("another-event", { your: "json data goes here" });
24
25        //
26        // Acknowledge that the message was handled correctly.
27        //
28        await res.ack();
29    });
30
31    //
32    // Create a HTTP GET request handler for a particular route.
33    // Do some work and return some json.
34    // Under the hood this is handled by Express, but the callback is wrapped for
35    // error handling, performance metrics and request tracing.
36    //
37    service.get('/another-end-point', async (req, res) => {
38        //
39        // ... do some work ...
40        //
41
42        //
43        // Respond to the request with some JSON data.
44        //
45        await res.json({
46            your: "json data"
47        });
48    });
49
50    //
51    // End points can be easily forwarded to internal services.
52    //
53    service.get('/another-end-point', async (req, res) => {
54        //
55        // Proxy the request to 'another-service'.
56        //
57        service.forwardRequest("another-service", "/a-different-end-point", { optionalQueryParameters: "go here" }, res);
58    });
59
60    //
61    // Initiate the service (a bit like like Express' listen function).
62    //
63    await service.start();
64
65}
66
67if (require.main === module) {
68
69
70    //
71    // Run nano service as normal.
72    //
73    const service = nano();
74
75    main(service)
76        .then(() => logger.info("Online"))
77        .catch(err => {
78            console.error("Failed to start!");
79            console.error(err && err.stack || err);
80        });
81}
82else {
83    //
84    // Don't start nanoservice, this allows the service to be loaded for unit testing.
85    //
86}

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.