It's possible to get next.js request object globally? - next.js

Question

I am using fastify with next.js and I need to include tracing (requestId is the problem so far). What I am doing right now is creating a fastify onRequest hook and generating a requestId value and setting it in request object (could be as a request header as well). What I want is to get access to this request object for two reasons:
In logger object (pino in this case, I want to include the requestId in all custom server-side logs).
In all request that needs to be made to other services need to include the requestId in headers.
Maybe I am missing something trivial and I'm not doing it the best way.
HERE SOME SNIPPETS
This how I am generating the reqId
const fastify = fastifyFactory({
logger, // logger configuration (Pino instance with custom configuration, see below)
genReqId: () => {
return Math.random()
.toString(36)
.slice(-6);
}
});
pino instance
const pino = require('pino');
const logger = pino({
messageKey: 'message',
prettyPrint: true,
changeLevelName: 'severity',
useLevelLabels: true,
base: {
serviceContext: {
service: 'web'
}
},
level:'info'
});
module.exports = {
logger
};
This is a plugin to gets the reqId generated and setting it to a query property within request object
const tracing = function tracing(fastify, opt, next) {
fastify.addHook('onRequest', (req, res, nextRequest) => {
const { id } = req;
const logger = fastify.log.child({ reqId: id });
req.query.reqId = id;
fastify.log = logger; //overrides the current fastify logger to include the reqId in all custom logs
nextRequest();
});
next();
};
tracing[Symbol.for('skip-override')] = true;
module.exports = tracing;
I have no problem when using fastify.log.info(...) because how logger is overrided in each request, it will include the reqId as a child log. The problem is that I want to create a generic logger to use at any part and fastify logger is not available in React components (for example to write logs at getInitialProps). Another important think is tha I need to include this reqId in all request I send to other services (ex: when fetching data), this is why I tried to store this value in request object but need to get it.

Answer 1

Starting from a project build with:
npx create-next-app --example custom-server-fastify custom-server-fastify-app
And changing the server.js with:
const Next = require('next')
const Fastify = require('fastify')
// your pino config
const fastify = Fastify({
logger: {
level: 'info',
prettyPrint: true,
changeLevelName: 'severity',
useLevelLabels: true,
base: {
serviceContext: {
service: 'web'
}
}
},
genReqId: () => { return Math.random().toString(36).slice(-6) }
})
// your plugin
const aPlugin = function yourPlugin (fastify, opts, next) {
fastify.addHook('onRequest', (request, reply, next) => {
request.log.info('hello')
const { id } = request
request.query.reqId = id
next()
})
next()
}
aPlugin[Symbol.for('skip-override')] = true
fastify.register(aPlugin)
[.... other generated code]
const port = parseInt(process.env.PORT, 10) || 3000
[.... other generated code]
fastify.get('/*', (req, reply) => {
console.log('-------->', req.id, req.query.reqId) // both your id is ok
return app.handleRequest(req.req, reply.res).then(() => {
reply.sent = true
})
[.... other generated code]
})
Then:
npm run dev
# another console
curl http://localhost:3000/
It will print out:
[1558441374784] INFO : Server listening at http://127.0.0.1:3000
serviceContext: {
"service": "web"
}
> Ready on http://localhost:3000
[1558441405416] INFO : incoming request
serviceContext: {
"service": "web"
}
reqId: "2i810l"
req: {
"method": "GET",
"url": "/",
"hostname": "localhost:3000",
"remoteAddress": "127.0.0.1",
"remotePort": 57863
}
req id ----> 2i810l
--------> 2i810l 2i810l
[ event ] build page: /
[ wait ] compiling ...
[1558441406171] INFO : request completed
serviceContext: {
"service": "web"
}
reqId: "2i810l"
res: {
"statusCode": 200
}
responseTime: 753.012099981308
So I think the misunderstanding is in the request object that is the Fastify request and not the Node.js "low level" request object, that could be accessed with request.req.
Moreover, running fastify.log = logger; is dangerous because it means that each request override and create a new logger and change the logger for the fastify instance, this is not safe, and as shown it is not necessary.
If you want more child logger (per route prefix per example) I suggest exploring/using the onRegister hook.
EDIT:
Now the custom hook print:
[1558443540483] INFO : hello
serviceContext: {
"service": "web"
}
reqId: "zjuhw2"