A middleware that generates a unique Request ID for every incoming HTTP request in Koa.

Installation

``bash


Using NPM

Use koa-request-id as a middleware for a koa app. By default, it generates a unique uuid (v4) and exposes it on the response via the X-Request-Id header. The id is also saved as part of the request state.

In the following example, the generated uuid is manually exposed on the body for debugging purposes:

`js
const Koa = require('koa');
const requestId = require('@kasa/koa-request-id');
const app = new Koa();

app.use(requestId());
app.use(async ctx => {
ctx.body = ctx.state.reqId;
});

app.listen(3000);
`

Execute a request to the running app:

`bash
❯ curl -v http://localhost:3000

< HTTP/1.1 200 OK
< X-Request-Id: a78598a4-6537-45eb-811c-fdc59602a54c

a78598a4-6537-45eb-811c-fdc59602a54c
`

Sometimes it is also useful to pass a custom id via a request header, specifically in tracking requests on the distributed system. Please note that the input id is not sanitized, so the usual precautions apply.

Using the above snippet to send a custom via the default X-Request-Id header:

`bash
❯ curl -v -H 'X-Request-Id: foobar' http://localhost:3000

< HTTP/1.1 200 OK
< X-Request-Id: foobar

foobar
`

API

$3

You can create a new request id middleware by passing the relevant options to requestId;

`node
// With default options
const middleware = requestId({
query: null,
header: 'X-Request-Id',
exposeHeader: 'X-Request-Id',
generator: require('uuid/v4')
});
`

$3

These are the available config options for the middleware. All is optional. The middleware try to get the request id from X-Request-Id request header or generate a new request id using uuidv4 generator. Then, the request id will be set into ctx.state.reqId Koa context state object and X-Request-Id response header if any option is not specified.

`node
{
// Request query name to get the forwarded request id
query: 'reqId',

// Request header name to get the forwarded request id
header: 'X-Transaction-Id',

// Response header name
exposeHeader: 'X-Transaction-Id',

// Function to generate request id
generator: () => Date.now().toString()
}
``

Contributing

#### Bug Reports & Feature Requests

Please use the issue tracker to report any bugs or ask feature requests.

License

Provided under the terms of the MIT License.

Copyright © 2018-2019, Kasa.