Add port and hostname options to Next Server

[javivelasco]

A middleware can work as a proxy intercepting requests and then performing a fetch to the destination adding headers to the request / response as a "man in the middle". When using fetch from a middleware we are not in the context of a browser so we can't really use relative URLs, they must be always absolute.

Now consider the previous case when middleware is running in server mode. Typically in order to know the host where we are fetching we can use the request.nextUrl which is given to the middleware but in this case the invoker (which is next-server) has no context of the hostname, nor the port. To solve this use case we must make the invoker of the middleware aware of the origin hostname and port.

This PR:

• Introduces hostname and port as options for NextServer.
• Refactors types in NextServer and NextDevServer moving type only imports to the top of the file.
• Refactors startServer to do a best guess on the hostname and port, passing them down.
• Exposes .port and .hostname to be retrieved from the app.

In an upcoming PR we will pass the host guess to the middleware to solve the relative URL issue.

[shuding]

Thanks for doing those improvements!

[ijjk]

Stats from current PR

Default Build (Increase detected ⚠️)

General Overall increase ⚠️

	vercel/next.js canary	javivelasco/next.js add/next-server-port	Change
buildDuration	19.3s	19s	-255ms
buildDurationCached	3.6s	3.5s	-78ms
nodeModulesSize	346 MB	346 MB	⚠️ +1.01 kB

Page Load Tests Overall increase ✓

	vercel/next.js canary	javivelasco/next.js add/next-server-port	Change
/ failed reqs	0	0	✓
/ total time (seconds)	3.286	3.299	⚠️ +0.01
/ avg req/sec	760.84	757.83	⚠️ -3.01
/error-in-render failed reqs	0	0	✓
/error-in-render total time (seconds)	1.47	1.341	-0.13
/error-in-render avg req/sec	1700.21	1864.27	+164.06

Client Bundles (main, webpack, commons)

	vercel/next.js canary	javivelasco/next.js add/next-server-port	Change
450.HASH.js gzip	179 B	179 B	✓
framework-HASH.js gzip	42.2 kB	42.2 kB	✓
main-HASH.js gzip	28.4 kB	28.4 kB	✓
webpack-HASH.js gzip	1.45 kB	1.45 kB	✓
Overall change	72.2 kB	72.2 kB	✓

Legacy Client Bundles (polyfills)

	vercel/next.js canary	javivelasco/next.js add/next-server-port	Change
polyfills-HASH.js gzip	31 kB	31 kB	✓
Overall change	31 kB	31 kB	✓

Client Pages

	vercel/next.js canary	javivelasco/next.js add/next-server-port	Change
_app-HASH.js gzip	1.37 kB	1.37 kB	✓
_error-HASH.js gzip	194 B	194 B	✓
amp-HASH.js gzip	312 B	312 B	✓
css-HASH.js gzip	327 B	327 B	✓
dynamic-HASH.js gzip	2.38 kB	2.38 kB	✓
head-HASH.js gzip	350 B	350 B	✓
hooks-HASH.js gzip	635 B	635 B	✓
image-HASH.js gzip	4.45 kB	4.45 kB	✓
index-HASH.js gzip	263 B	263 B	✓
link-HASH.js gzip	1.87 kB	1.87 kB	✓
routerDirect..HASH.js gzip	321 B	321 B	✓
script-HASH.js gzip	383 B	383 B	✓
withRouter-HASH.js gzip	318 B	318 B	✓
85e02e95b279..7e3.css gzip	107 B	107 B	✓
Overall change	13.3 kB	13.3 kB	✓

Client Build Manifests

	vercel/next.js canary	javivelasco/next.js add/next-server-port	Change
_buildManifest.js gzip	460 B	460 B	✓
Overall change	460 B	460 B	✓

Rendered Page Sizes

	vercel/next.js canary	javivelasco/next.js add/next-server-port	Change
index.html gzip	532 B	532 B	✓
link.html gzip	545 B	545 B	✓
withRouter.html gzip	526 B	526 B	✓
Overall change	1.6 kB	1.6 kB	✓

---

Default Build with SWC (Decrease detected ✓)

General Overall increase ⚠️

	vercel/next.js canary	javivelasco/next.js add/next-server-port	Change
buildDuration	20.5s	20.2s	-291ms
buildDurationCached	3.7s	3.6s	-66ms
nodeModulesSize	346 MB	346 MB	⚠️ +1.01 kB

Page Load Tests Overall decrease ⚠️

	vercel/next.js canary	javivelasco/next.js add/next-server-port	Change
/ failed reqs	0	0	✓
/ total time (seconds)	2.946	3.048	⚠️ +0.1
/ avg req/sec	848.63	820.17	⚠️ -28.46
/error-in-render failed reqs	0	0	✓
/error-in-render total time (seconds)	1.428	1.525	⚠️ +0.1
/error-in-render avg req/sec	1751.02	1639.61	⚠️ -111.41

Client Bundles (main, webpack, commons)

	vercel/next.js canary	javivelasco/next.js add/next-server-port	Change
450.HASH.js gzip	179 B	179 B	✓
framework-HASH.js gzip	42.3 kB	42.3 kB	✓
main-HASH.js gzip	28.6 kB	28.6 kB	✓
webpack-HASH.js gzip	1.44 kB	1.44 kB	✓
Overall change	72.5 kB	72.5 kB	✓

Legacy Client Bundles (polyfills)

	vercel/next.js canary	javivelasco/next.js add/next-server-port	Change
polyfills-HASH.js gzip	31 kB	31 kB	✓
Overall change	31 kB	31 kB	✓

Client Pages

	vercel/next.js canary	javivelasco/next.js add/next-server-port	Change
_app-HASH.js gzip	1.35 kB	1.35 kB	✓
_error-HASH.js gzip	180 B	180 B	✓
amp-HASH.js gzip	305 B	305 B	✓
css-HASH.js gzip	321 B	321 B	✓
dynamic-HASH.js gzip	2.37 kB	2.37 kB	✓
head-HASH.js gzip	342 B	342 B	✓
hooks-HASH.js gzip	622 B	622 B	✓
image-HASH.js gzip	4.47 kB	4.47 kB	✓
index-HASH.js gzip	256 B	256 B	✓
link-HASH.js gzip	1.91 kB	1.91 kB	✓
routerDirect..HASH.js gzip	314 B	314 B	✓
script-HASH.js gzip	375 B	375 B	✓
withRouter-HASH.js gzip	309 B	309 B	✓
85e02e95b279..7e3.css gzip	107 B	107 B	✓
Overall change	13.2 kB	13.2 kB	✓

Client Build Manifests

	vercel/next.js canary	javivelasco/next.js add/next-server-port	Change
_buildManifest.js gzip	458 B	458 B	✓
Overall change	458 B	458 B	✓

Rendered Page Sizes

	vercel/next.js canary	javivelasco/next.js add/next-server-port	Change
index.html gzip	532 B	532 B	✓
link.html gzip	544 B	544 B	✓
withRouter.html gzip	526 B	526 B	✓
Overall change	1.6 kB	1.6 kB	✓

Commit: 13afd22