[NextjsSite construct] add basePath support back into NextjsSite construct

[jplwood]

Partially addresses #2964

The original, now-deprecated version of the NextjsSite construct (as far as I can tell, it's deprecated because the non-deprecated construct uses SsrSite as a base, whereas the deprecated one doesn't?) supported basePath(see deprecated code, and Next.js docs on basePath), a crucial feature for hosting apps behind a reverse proxy (and a major convenience when linking around if all of your app's routes are all heavily nested). When the new version of NextjsSite construct was released, basePath support seemed to have been removed.

This PR takes that original functionality and adds it back to the new NextjsSite construct.

Unclear if this is safely additive or if it's a breaking change.

[changeset-bot]

🦋 Changeset detected

Latest commit: ce73cb0

The changes in this PR will be included in the next version bump.

This PR includes changesets to release 6 packages

Name	Type
sst	Patch
@sst/console	Patch
create-sst	Patch
astro-sst	Patch
svelte-kit-sst	Patch
solid-start-sst	Patch

Not sure what this means? Click here to learn what changesets are.

Click here if you're a maintainer who wants to add another changeset to this PR

[jplwood]

Taken from:

sst/packages/sst/src/constructs/deprecated/NextjsSite.ts

Lines 1406 to 1411 in d6917d8

	private pathPattern(pattern: string): string {
	const { basePath } = this.routesManifest || {};
	return basePath && basePath.length > 0
	? `${basePath.slice(1)}/${pattern}`
	: pattern;
	}

[jayair]

Thanks! Let me ask the team to review.

[jplwood]

@jayair any updates here? We're nearing the end of our evaluation period of SST and hoping to use this getting released as an example of our ability to influence/improve community implementations (as an alternative to doing things more in-house)

[jayair]

Ah I see. Let me see if I can bump up the timeframe on this. We've been a little behind after the holidays.

[justindra]

Just pulled this down and tested it and it seems to work for my stuff. Thanks @jplwood

[josepardo-eb]

@jayair any idea about when this could be merged?

[jayair]

Oh no, let me see why it didn't get merged.