`node` formula should depend on Python only during build phase

[raphlcx]

brew gist-logs <formula> link OR brew config AND brew doctor output

$ brew config

HOMEBREW_VERSION: 3.2.17-133-g890190c
ORIGIN: https://github.com/Homebrew/brew
HEAD: 890190c0f30b36512835c846be004b0253b062ad
Last commit: 31 hours ago
Core tap ORIGIN: https://github.com/Homebrew/homebrew-core
Core tap HEAD: 26a841653a5d824cec69d1ae60b0b3de3c2f18e3
Core tap last commit: 37 minutes ago
Core tap branch: master
HOMEBREW_PREFIX: /usr/local
HOMEBREW_CASK_OPTS: []
HOMEBREW_CLEANUP_MAX_AGE_DAYS: 0
HOMEBREW_CORE_GIT_REMOTE: https://github.com/Homebrew/homebrew-core
HOMEBREW_EDITOR: vim
HOMEBREW_MAKE_JOBS: 4
HOMEBREW_NO_AUTO_UPDATE: set
Homebrew Ruby: 2.6.3 => /System/Library/Frameworks/Ruby.framework/Versions/2.6/usr/bin/ruby
CPU: quad-core 64-bit broadwell
Clang: 13.0.0 build 1300
Git: 2.33.1 => /usr/local/bin/git
Curl: 7.64.1 => /usr/bin/curl
macOS: 11.6-x86_64
CLT: 13.0.0.0.1.1630607135
Xcode: 13.0

$ brew doctor

Please note that these warnings are just used to help the Homebrew maintainers
with debugging if you file an issue. If everything you use Homebrew for is
working fine: please don't worry or file an issue; just ignore this. Thanks!

Warning: The filesystem on /System/Volumes/Data appears to be case-sensitive.
The default macOS filesystem is case-insensitive. Please report any apparent problems.

Warning: Putting non-prefixed coreutils in your path can cause GMP builds to fail.

• I ran brew update and am still able to reproduce my issue.
• I have resolved all warnings from brew doctor and that did not fix my problem.

What were you trying to do (and why)?

Good day Homebrew,

I'm looking through the formulae that I have installed on my machine, identifying which one of them depends on Python during runtime.

And I noticed the node formula has a runtime dependency on Python, but from my reading up to this point, this dependency is only required when building node, not during runtime:

• On Node.js official documentation, it mentions the use of Python >=3 for building and testing. [ref]
• On Arch Linux Node.js package, Python is also mentioned as a dependency only during the build phase (stylised as (make)). [ref]

I have followed the conversation in #86894, but there seems to be no mention of adding Python only as a build-time dependency.

I have tried turning Python from runtime to build-time dependency for the formula:

diff --git a/Formula/node.rb b/Formula/node.rb
index ed304dc55d1..ce0e602a478 100644
--- a/Formula/node.rb
+++ b/Formula/node.rb
@@ -27,7 +27,7 @@ class Node < Formula
   depends_on "libnghttp2"
   depends_on "libuv"
   depends_on "openssl@1.1"
-  depends_on "python@3.9"
+  depends_on "python@3.9" => :build
 
   uses_from_macos "zlib"
 

Then I was able to build from source and run the tests successfully for the formula:

(I had an active tmux split pane, so the output got clipped)

$ brew install --build-from-source node
==> Downloading https://ghcr.io/v2/homebrew/core/python/3.9/manifests/3.9.7_1
######################################################################## 100.0%
==> Downloading https://ghcr.io/v2/homebrew/core/python/3.9/blobs/sha256:c08c5f01bca862fd69d511261
==> Downloading from https://pkg-containers.githubusercontent.com/ghcr1/blobs/sha256:c08c5f01bca86
######################################################################## 100.0%
==> Downloading https://github.com/nodejs/node/commit/8699aa501c4d4e1567ebe8901e5ec80cadaa9323.pat
######################################################################## 100.0%
==> Downloading https://registry.npmjs.org/npm/-/npm-8.1.0.tgz
######################################################################## 100.0%
==> Downloading https://nodejs.org/dist/v17.0.1/node-v17.0.1.tar.xz
######################################################################## 100.0%
==> Installing dependencies for node: python@3.9
==> Installing node dependency: python@3.9
==> Pouring python@3.9--3.9.7_1.big_sur.bottle.tar.gz
==> /usr/local/Cellar/python@3.9/3.9.7_1/bin/python3 -m ensurepip
==> /usr/local/Cellar/python@3.9/3.9.7_1/bin/python3 -m pip install -v --no-deps --no-index --upgr
🍺  /usr/local/Cellar/python@3.9/3.9.7_1: 3,080 files, 54.7MB
==> Installing node
==> Patching
==> Applying 8699aa501c4d4e1567ebe8901e5ec80cadaa9323.patch
patching file src/cares_wrap.h
==> ./configure --prefix=/usr/local/Cellar/node/17.0.1 --without-npm --with-intl=system-icu --shar
==> make install
==> node /private/tmp/node-20211024-83467-l7wt2o/node-v17.0.1/npm_bootstrap/bin/npm-cli.js install
🍺  /usr/local/Cellar/node/17.0.1: 2,008 files, 45.1MB, built in 79 minutes 10 seconds
Removing: /Users/cx/Library/Caches/Homebrew/node--npm--8.1.0.tgz... (2.1MB)
Removing: /Users/cx/Library/Caches/Homebrew/node--patch--678643c79258372d5054d3da16bc0c5db17130f151f0e72b6e4f20817987aac9.patch... (1.2KB)
Removing: /Users/cx/Library/Caches/Homebrew/node--17.0.1.tar.xz... (33.1MB)

$ brew test node
==> Testing node
==> /usr/local/Cellar/node/17.0.1/bin/node /private/tmp/node-test-20211024-51438-qkkshk/test.js
==> /usr/local/Cellar/node/17.0.1/bin/node -e 'console.log(new Intl.NumberFormat("en-EN").format(1234.56))'
==> /usr/local/Cellar/node/17.0.1/bin/node -e 'console.log(new Intl.NumberFormat("de-DE").format(1234.56))'
==> /usr/local/bin/npm -ddd --cache=/Users/cx/Library/Caches/Homebrew/npm_cache --build-from-source install npm@latest
==> /usr/local/bin/npm -ddd --cache=/Users/cx/Library/Caches/Homebrew/npm_cache --build-from-source install ref-napi
==> /usr/local/bin/npx --yes cowsay hello
npm notice
npm notice New patch version of npm available! 8.1.0 -> 8.1.1
npm notice Changelog: https://github.com/npm/cli/releases/tag/v8.1.1
npm notice Run npm install -g npm@8.1.1 to update!
npm notice

I think this could help to proof that Python is indeed only required as a build-time dependency of node, and not during runtime, although I might be missing a few points or notes in a coversation somewhere that could disprove my rationale.

Hope to hear soon.

What happened (include all command output)?

$ brew deps node | grep python
python@3.9

node formula shows Python as one of its dependencies.

What did you expect to happen?

$ brew deps node | grep python

This command should not display anything.

Step-by-step reproduction instructions (by running brew commands)

brew deps node | grep python

[carlocab]

Running brew test node on a system with no Python3 (or one that is older than 3.6) installed produces errors (try this, for example, in the Homebrew Docker container).

Python3 was already a build-dependency of Node prior to #86894, but that did not prevent failures while attempting to use Node after the build completed.

[raphlcx]

Python3 was already a build-dependency of Node prior to #86894, but that did not prevent failures while attempting to use Node after the build completed.

I see, I had missed that, thanks for pointing it out.

One of the tests that installs ref-napi using npm [ref], is that one that fails the test:

npm ERR! gyp ERR! System Linux 4.14.246-187.474.amzn2.x86_64
npm ERR! gyp ERR! command "/home/linuxbrew/.linuxbrew/Cellar/node/17.0.1/bin/node" "/home/linuxbrew/.linuxbrew/lib/node_modules/npm/node_modules/node-gyp/bin/node-gyp.js" "rebuild"
npm ERR! gyp ERR! cwd /tmp/node-test-20211024-20565-woonqt/node_modules/ref-napi
npm ERR! gyp ERR! node -v v17.0.1
npm ERR! gyp ERR! node-gyp -v v8.2.0
npm ERR! gyp ERR! not ok
npm verb exit 1

Installing ref-napi requires node-gyp, which in turns requires Python.

I think it does test the case of a user installing packages with npm, a package that requires node-gyp, but, Python is a dependency of the node-gyp library, and not directly on the node formula itself.

(Edit: I think I jumped ahead too much in my previous comment. Let's first chat on the dependency of node-gyp library on Python, and it is not node itself that depends on Python.)

[SMillerDev]

Python is a dependency of the node-gyp library, and not directly on the node formula itself.

Since there is no node-gyp formula, these two things are essentially the same and therefore we need to have node depend on python.

[raphlcx]

node-gyp is only used when running tests on the node formula. I'm not sure if it is best to group the two things as the same, although having Python installed does contribute positively to the subsequent installation of packages from the Node.js ecosystem.

If Python is to remain as a runtime dependency of the node formula, I think it is only a dependency, in the form of providing convenience to the user, rather than a strict dependency that is required to run node.

According to the formula cookbook, there are other types of dependency that we can specify, e.g. :recommended, :optional, are these still valid and in use in Homebrew?

[carlocab]

You can still use them in external taps, but they're no longer in use in Homebrew/core.

[raphlcx]

I see.

Thanks for following up until this point @SMillerDev @carlocab.

I think we can close this issue now, if no changes will be made for separating Python from node's runtime dependency.

[SMillerDev]

Thanks for bringing this up @raphlcx! even though we didn't end up implementing your request, the insights are appreciated.

[tuzi3040]

Maybe now we can make Python3 back to build-dependency on MacOS?

Mojave is not actively supported and bottled any more, and Python3 >= 3.7.3 is installed by Command Line Tools, which is required by installation of HomeBrew, since Catalina.

[tuzi3040]

@carlocab @SMillerDev any thoughts?

[carlocab]

See #89068. We probably also need a uses_from_macos "python3", since: :catalina or similar.