feat: allow dotenv default expansion

[balazsorban44]

We currently use dotenv-expand@5 in @next/env, which does not support default expansion. It was added in v6 (motdotla/dotenv-expand#39).

Upgrading to the latest version of dotenv-expand and fixing an import, the added test passed.

Fixes #34718

Bug

• Related issues linked using fixes #number
• Integration tests added
• Errors have helpful link attached, see contributing.md

Feature

• Implements an existing feature request or RFC. Make sure the feature request has been accepted for implementation before opening a PR.
• Related issues linked using fixes #number
• Integration tests added
• Documentation added
• Telemetry added. In case of a feature if it's used or not.
• Errors have helpful link attached, see contributing.md

Documentation / Examples

• Make sure the linting passes by running yarn lint

[timneutkens]

Looks fine 👍

[ijjk]

Stats from current PR

Default Build (Decrease detected ✓)

General Overall increase ⚠️

	vercel/next.js canary	vercel/next.js feat/allow-dotenv-expand	Change
buildDuration	15.4s	15.7s	⚠️ +242ms
buildDurationCached	6.2s	6.1s	-88ms
nodeModulesSize	372 MB	372 MB	⚠️ +155 B

Page Load Tests Overall decrease ⚠️

	vercel/next.js canary	vercel/next.js feat/allow-dotenv-expand	Change
/ failed reqs	0	0	✓
/ total time (seconds)	2.948	2.942	-0.01
/ avg req/sec	848.06	849.71	+1.65
/error-in-render failed reqs	0	0	✓
/error-in-render total time (seconds)	1.192	1.198	⚠️ +0.01
/error-in-render avg req/sec	2097.42	2086	⚠️ -11.42

Client Bundles (main, webpack)

	vercel/next.js canary	vercel/next.js feat/allow-dotenv-expand	Change
925.HASH.js gzip	179 B	179 B	✓
framework-HASH.js gzip	42 kB	42 kB	✓
main-HASH.js gzip	27.9 kB	27.9 kB	✓
webpack-HASH.js gzip	1.44 kB	1.44 kB	✓
Overall change	71.5 kB	71.5 kB	✓

Legacy Client Bundles (polyfills)

	vercel/next.js canary	vercel/next.js feat/allow-dotenv-expand	Change
polyfills-HASH.js gzip	31 kB	31 kB	✓
Overall change	31 kB	31 kB	✓

Client Pages

	vercel/next.js canary	vercel/next.js feat/allow-dotenv-expand	Change
_app-HASH.js gzip	1.36 kB	1.36 kB	✓
_error-HASH.js gzip	192 B	192 B	✓
amp-HASH.js gzip	309 B	309 B	✓
css-HASH.js gzip	327 B	327 B	✓
dynamic-HASH.js gzip	2.57 kB	2.57 kB	✓
head-HASH.js gzip	351 B	351 B	✓
hooks-HASH.js gzip	920 B	920 B	✓
image-HASH.js gzip	5.06 kB	5.06 kB	✓
index-HASH.js gzip	263 B	263 B	✓
link-HASH.js gzip	2.26 kB	2.26 kB	✓
routerDirect..HASH.js gzip	320 B	320 B	✓
script-HASH.js gzip	387 B	387 B	✓
withRouter-HASH.js gzip	319 B	319 B	✓
85e02e95b279..7e3.css gzip	107 B	107 B	✓
Overall change	14.8 kB	14.8 kB	✓

Client Build Manifests

	vercel/next.js canary	vercel/next.js feat/allow-dotenv-expand	Change
_buildManifest.js gzip	460 B	460 B	✓
Overall change	460 B	460 B	✓

Rendered Page Sizes

	vercel/next.js canary	vercel/next.js feat/allow-dotenv-expand	Change
index.html gzip	532 B	532 B	✓
link.html gzip	545 B	545 B	✓
withRouter.html gzip	525 B	525 B	✓
Overall change	1.6 kB	1.6 kB	✓

---

Default Build with SWC (Decrease detected ✓)

General Overall increase ⚠️

	vercel/next.js canary	vercel/next.js feat/allow-dotenv-expand	Change
buildDuration	18.7s	18.5s	-179ms
buildDurationCached	6.1s	6s	-58ms
nodeModulesSize	372 MB	372 MB	⚠️ +155 B

Page Load Tests Overall decrease ⚠️

	vercel/next.js canary	vercel/next.js feat/allow-dotenv-expand	Change
/ failed reqs	0	0	✓
/ total time (seconds)	2.92	2.916	0
/ avg req/sec	856.15	857.39	+1.24
/error-in-render failed reqs	0	0	✓
/error-in-render total time (seconds)	1.173	1.195	⚠️ +0.02
/error-in-render avg req/sec	2130.45	2092.27	⚠️ -38.18

Client Bundles (main, webpack)

	vercel/next.js canary	vercel/next.js feat/allow-dotenv-expand	Change
925.HASH.js gzip	178 B	178 B	✓
framework-HASH.js gzip	42.3 kB	42.3 kB	✓
main-HASH.js gzip	28.1 kB	28.1 kB	✓
webpack-HASH.js gzip	1.45 kB	1.45 kB	✓
Overall change	72.1 kB	72.1 kB	✓

Legacy Client Bundles (polyfills)

	vercel/next.js canary	vercel/next.js feat/allow-dotenv-expand	Change
polyfills-HASH.js gzip	31 kB	31 kB	✓
Overall change	31 kB	31 kB	✓

Client Pages

	vercel/next.js canary	vercel/next.js feat/allow-dotenv-expand	Change
_app-HASH.js gzip	1.36 kB	1.36 kB	✓
_error-HASH.js gzip	179 B	179 B	✓
amp-HASH.js gzip	313 B	313 B	✓
css-HASH.js gzip	324 B	324 B	✓
dynamic-HASH.js gzip	2.56 kB	2.56 kB	✓
head-HASH.js gzip	351 B	351 B	✓
hooks-HASH.js gzip	921 B	921 B	✓
image-HASH.js gzip	5.2 kB	5.2 kB	✓
index-HASH.js gzip	261 B	261 B	✓
link-HASH.js gzip	2.33 kB	2.33 kB	✓
routerDirect..HASH.js gzip	322 B	322 B	✓
script-HASH.js gzip	388 B	388 B	✓
withRouter-HASH.js gzip	317 B	317 B	✓
85e02e95b279..7e3.css gzip	107 B	107 B	✓
Overall change	14.9 kB	14.9 kB	✓

Client Build Manifests

	vercel/next.js canary	vercel/next.js feat/allow-dotenv-expand	Change
_buildManifest.js gzip	458 B	458 B	✓
Overall change	458 B	458 B	✓

Rendered Page Sizes

	vercel/next.js canary	vercel/next.js feat/allow-dotenv-expand	Change
index.html gzip	530 B	530 B	✓
link.html gzip	543 B	543 B	✓
withRouter.html gzip	525 B	525 B	✓
Overall change	1.6 kB	1.6 kB	✓

Commit: 2838024

[FezVrasta]

Has this been published already? The latest next.js version doesn't seem to support this yet. Not even 12.1.3-canary.0 seems to include the change.

[FezVrasta]

Actually, I see the updated dotenv-expand version on 12.1.2 (https://unpkg.com/browse/@next/env@12.1.2/package.json) but it's not working. May someone confirm please?

[hckhanh]

Me too, I come here from the #35818

[FezVrasta]

It looks like dotenv-expand has a bug. I fixed it here but nobody from the maintainers replied yet.

motdotla/dotenv-expand#74

[MattIPv4]

This also introduced motdotla/dotenv-expand#65 to env parsing