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Empty NEXT_PUBLIC_* environment variables are evaluated as undefined rather than as empty strings #64832

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bryan-hoang opened this issue Apr 20, 2024 · 5 comments · May be fixed by #65248
Open

Empty NEXT_PUBLIC_* environment variables are evaluated as undefined rather than as empty strings #64832

bryan-hoang opened this issue Apr 20, 2024 · 5 comments · May be fixed by #65248
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bug Issue was opened via the bug report template. Output (export/standalone) Related to the the output option in `next.config.js`. Pages Router Related to Pages Router.

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@bryan-hoang
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bryan-hoang commented Apr 20, 2024 •
edited

Link to the code that reproduces this issue

https://github.com/bryan-hoang/repro-undefined-next-public-env-vars

To Reproduce

  1. Run pnpm exec next dev
  2. Observe that the website is displaying process.env.NEXT_PUBLIC_FOO: undefined.

Current vs. Expected behavior

I expected process.env.NEXT_PUBLIC_FOO: to be displayed instead, since the .env file contains NEXT_PUBLIC_FOO=. The environment variable is defined as an empty string, but it's not being evaluated as one.

I find it surprising that environment variables that are defined as empty strings be treated as undefined.

Provide environment information

Operating System:
  Platform: linux
  Arch: x64
  Version: #28~22.04.1-Ubuntu SMP PREEMPT_DYNAMIC Fri Mar 15 10:51:06 UTC 2
  Available memory (MB): 773973
  Available CPU cores: 48
Binaries:
  Node: 21.7.3
  npm: 10.5.2
  Yarn: N/A
  pnpm: 9.0.4
Relevant Packages:
  next: 14.3.0-canary.13 // Latest available version is detected (14.3.0-canary.13).
  eslint-config-next: N/A
  react: 18.2.0
  react-dom: 18.2.0
  typescript: 5.1.3
Next.js Config:
  output: N/A

Which area(s) are affected? (Select all that apply)

Output (export/standalone), Pages Router

Which stage(s) are affected? (Select all that apply)

next dev (local), next build (local), next start (local)

Additional context

It looks like this issue was first introduced in [email protected], as reverting to [email protected] fixes the issue.

After looking at the commits between those canary versions, I think the commit that introduced the issue is 76c9496. Specifically, this part of the diff: 76c9496#diff-28c0329619b90836564a7769c43ff473dbd28e8e31b75e650624da4d06911763R68.

Since empty strings are falsey, the environment variable doesn't end up being set.

The same guard against falsey values is present on the current canary version as of writing this.
@bryan-hoang bryan-hoang added the bug Issue was opened via the bug report template. label Apr 20, 2024
@github-actions github-actions bot added Output (export/standalone) Related to the the output option in `next.config.js`. Pages Router Related to Pages Router. labels Apr 20, 2024
bryan-hoang added a commit to bryan-hoang/distributive-people-page that referenced this issue Apr 21, 2024
@bryan-hoang
fix: handle bash path as empty string
4b5d6f2 
See vercel/next.js#64832
@timlindsk
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timlindsk commented Apr 23, 2024 •
edited

Agreed, this bug silently broke redirection-links for us where we sometimes use different base-paths depending on the environment. I feel like we should be able to expect it to be evaluated as a string when set like one.
NEXT_PUBLIC_BASE_PATH=''

As a temporary fix we reverted to 14.1.4 in wait for a real fix

@timlindsk timlindsk mentioned this issue Apr 23, 2024
Open
bryan-hoang added a commit to bryan-hoang/distributive-people-page that referenced this issue Apr 23, 2024
@bryan-hoang
fix: handle base path environment variable as empty string
0559c92 
See vercel/next.js#64832
@icyJoseph icyJoseph linked a pull request May 1, 2024 that will close this issue
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@icyJoseph
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Nice catch! I've made a PR for it, hopefully it gets reviewed soon

@icyJoseph
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Agreed, this bug silently broke redirection-links for us where we sometimes use different base-paths depending on the environment. I feel like we should be able to expect it to be evaluated as a string when set like one. NEXT_PUBLIC_BASE_PATH=''

As a temporary fix we reverted to 14.1.4 in wait for a real fix

@timlindsk hi, could you show us a small reproduction set of steps, or better yet a repository? I would like to verify that the proposed fix also fixes your issue.

@timlindsk
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It's pretty much an ordinary nextjs setup with NEXT_PUBLIC_BASE_PATH='' in .env, then I'm using it in a utilities function that's returning:
${window.location.origin}${process.env.NEXT_PUBLIC_BASE_PATH}, where it's then called from a function within a page component like: ${appURL()}${path} to create a url. All of which have worked fine before.

Sidenote, separate issue, while troubleshooting: I also stumbled upon an issue where compiling mui/icons-material ended up in a crash because "use strict"; was on top of "use client"; But I have yet to boil down the root of that problem, it seems to be related to a later version of nextjs, but I'm also not sure as what the best practice is regarding it, if they should be switched around by mui/icons-material I mean, or if nextjs should allow for it. Can't seem to find much about it other than the case where there's no "use client"; at all. Any pointer?

@icyJoseph
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It's pretty much an ordinary nextjs setup with NEXT_PUBLIC_BASE_PATH='' in .env, then I'm using it in a utilities function that's returning: ${window.location.origin}${process.env.NEXT_PUBLIC_BASE_PATH}, where it's then called from a function within a page component like: ${appURL()}${path} to create a url. All of which have worked fine before.

Alright, then yea I think this should also cover that.

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bug Issue was opened via the bug report template. Output (export/standalone) Related to the the output option in `next.config.js`. Pages Router Related to Pages Router.
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fix: Narrow down from string | undefined to string icyJoseph/next.js
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@icyJoseph @bryan-hoang @timlindsk