Allow configuring Homebrew with `.env` files #15787

MikeMcQuaid · 2023-07-28T14:54:14Z

For a long time people have requested some sort of configuration files for Homebrew. Now: here's the first version of that.

Similarly to how you can configure Git for a system, a repository or a user: you can configure Homebrew for a system, a prefix or a user.

The system-wide configuration file is /etc/homebrew/brew.env, the prefix-specific configuration file is $HOMEBREW_PREFIX/etc/homebrew/brew.env and the user-specific configuration file is ~/.homebrew/brew.env.

As we need to read these files from Bash in bin/brew (so they can) influence functionality ASAP: they are in a simple format that Bash can read. It may be that we have more complex array or hash data in future that's configured through JSON or YAML (most likely JSON as we use it more) and stored in a brew.json/brew.yaml file in the same directory.

As this is relying on eval in Bash which is fairly dangerous: we filter the lines with a regex to ensure we're only permitting setting HOMEBREW_* variables and nothing more.

To give a bit of power to system administrators, the HOMEBREW_SYSTEM_ENV_TAKES_PRIORITY variable can be set in /etc/homebrew/brew.env to ensure that the system-wide configuration file is loaded last and overrides any prefix or user settings.

Now that we have an actual location for configuration files, let's also change the brew livecheck watchlist configuration file to be in this directory and deprecate the existing location. As this is a developer command and the mitigation is to just move the file: we don't need to follow the normal deprecation process here.

bin/brew

carlocab · 2023-07-28T15:21:53Z

bin/brew

+  unset SYSTEM_ENV_TAKES_PRIORITY
+  # only load HOMEBREW_*=* lines
+  SYSTEM_HOMEBREW_ENV="$(grep -E '^HOMEBREW_[A-Z]+=.*$' "/etc/homebrew/brew.env")"
+  if [[ -n "${HOMEBREW_SYSTEM_ENV_TAKES_PRIORITY-}" ]]


Would be nice to check for whether this is set in /etc/homebrew/brew.env.

@carlocab to avoid it being set by the environment or something else? Allowing it to be set from environment makes testing a bunch easier.

More to allow the administrator of /etc/homebrew/brew.env to decide whether the system env takes priority or not. Otherwise users can just do unset HOMEBREW_SYSTEM_ENV_TAKES_PRIORITY. We can take the value from the environment too if it's not set in the system env.

But I'm not bothered if you'd rather someone who needed it implemented this.

Library/Homebrew/manpages/brew.1.md.erb

For a long time people have requested some sort of configuration files for Homebrew. Now: here's the first version of that. Similarly to how you can configure Git for a system, a repository or a user: you can configure Homebrew for a system, a prefix or a user. The system-wide configuration file is `/etc/homebrew/brew.env`, the prefix-specific configuration file is `$HOMEBREW_PREFIX/etc/homebrew/brew.env` and the user-specific configuration file is `~/.homebrew/brew.env`. As we need to read these files from Bash in `bin/brew` (so they can) influence functionality ASAP: they are in a simple format that Bash can read. It may be that we have more complex array or hash data in future that's configured through JSON or YAML (most likely JSON as we use it more) and stored in a `brew.json`/`brew.yaml` file in the same directory. As this is relying on `eval` in Bash which is fairly dangerous: we filter the lines with a regex to ensure we're only permitting setting `HOMEBREW_*` variables and nothing more. To give a bit of power to system administrators, the `HOMEBREW_SYSTEM_ENV_TAKES_PRIORITY` variable can be set in `/etc/homebrew/brew.env` to ensure that the system-wide configuration file is loaded last and overrides any prefix or user settings. Now that we have an actual location for configuration files, let's also change the `brew livecheck` watchlist configuration file to be in this directory and deprecate the existing location. As this is a developer command and the mitigation is to just move the file: we don't need to follow the normal deprecation process here.

carlocab · 2023-07-28T16:24:38Z

bin/brew

+if [[ -n "${XDG_CONFIG_HOME-}" ]]
+then
+  HOMEBREW_USER_CONFIG_HOME="${XDG_CONFIG_HOME}/homebrew"


Suggested change

if [[ -n "${XDG_CONFIG_HOME-}" ]]

then

HOMEBREW_USER_CONFIG_HOME="${XDG_CONFIG_HOME}/homebrew"

if [[ -n "${HOMEBREW_XDG_CONFIG_HOME-}" ]]

then

HOMEBREW_USER_CONFIG_HOME="${HOMEBREW_XDG_CONFIG_HOME}/homebrew"

and XDG_CONFIG_HOME needs to be added to USED_BY_HOMEBREW_VARS in bin/brew.

@carlocab Can you explain that? I don't think either should be needed.

Env filtering:

❯ XDG_CONFIG_HOME=foo brew ruby -e 'puts ENV["XDG_CONFIG_HOME"].present?' false

@carlocab We don't rely on XDG_CONFIG_HOME being set anywhere after env filtering is applied (unless I missed something), no?

Ah, sorry, I thought this was in brew.sh. 😅 That said, don't we want to have the same behaviour for the livecheck watchlist? i.e. check $XDG_CONFIG_HOME/homebrew/livecheck_watchlist.txt if XDG_CONFIG_HOME is set?

@carlocab that behaviour is already present. We don't pass through XDG_CONFIG_HOME because we don't want/need to. It's documented that we use it if set but that's only needed/used in brew.sh which in turn sets HOMEBREW_USER_CONFIG_HOME accordingly and that is used afterwards.

For an example:

$ export XDG_CONFIG_HOME=fish[~/OSS/Homebrew] $ brew irb ==> Interactive Homebrew Shell ... brew(main):001:0> ENV["HOMEBREW_USER_CONFIG_HOME"] => "fish/homebrew"

carlocab

Aha, yes. I clearly did not understand the changes here. Thanks for bearing with me!

MikeMcQuaid · 2023-08-01T12:07:14Z

@carlocab you're very welcome, thanks for the review! ❤️

cdalvaro · 2023-08-03T15:18:53Z

Hi!

After this change, I'm having issues running salt with brew.

Every state I try to run with brew fails with the following error message:

[salt.loaded.int.module.cmdmod:920 ][ERROR   ][737] Command 'brew' failed with return code: 1
[salt.loaded.int.module.cmdmod:922 ][ERROR   ][737] stdout: /opt/homebrew/bin/brew: line 109: HOME: unbound variable

I've checked how salt runs brew commands, and this is how it does it:

https://github.com/saltstack/salt/blob/4e8b77df671fd756970fe4fb08122fba9b47c50b/salt/modules/mac_brew_pkg.py#L112-L115

    if runas:
        _cmd = ["sudo -i -n -H -u {} -- ".format(runas)]
    _cmd = _cmd + [salt.utils.path.which("brew")] + list(cmd)
    _cmd = " ".join(_cmd)

It apparently tries to set the HOME env variable by calling sudo with -H. But looking at the error message it doesn't seem to work.

However, I've not been able to reproduce the error in any other more isolated way.

Update: As a temporary fix, I have checkout my Homebrew installation to point to the latest release:

git -C ${fetch --all
git -C ${HOMEBREW_PREFIX} checkout 4.1.3

MikeMcQuaid · 2023-08-03T17:33:53Z

@cdalvaro I'll work on a fix for this tomorrow.

cdalvaro · 2023-08-03T17:49:04Z

Great!!! Thank you very much! Let me know if I can help you!

MikeMcQuaid · 2023-08-04T07:31:38Z

@cdalvaro Will be fixed by #15818

carlocab reviewed Jul 28, 2023

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MikeMcQuaid requested a review from carlocab July 31, 2023 11:55

carlocab approved these changes Aug 1, 2023

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MikeMcQuaid merged commit e3c0faf into Homebrew:master Aug 1, 2023
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MikeMcQuaid deleted the env_file_configuration branch August 1, 2023 12:07

MikeMcQuaid mentioned this pull request Aug 4, 2023

bin/brew: handle missing $HOME. #15818

Merged

cdalvaro mentioned this pull request Aug 4, 2023

[master] fix(mac_brew_pkg): Improve search for Homebrew's prefix saltstack/salt#64924

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3 tasks

samford mentioned this pull request Aug 16, 2023

dev-cmd/livecheck: avoid watchlist in test #15881

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7 tasks

github-actions bot added the outdated PR was locked due to age label Sep 4, 2023

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Allow configuring Homebrew with `.env` files #15787

Allow configuring Homebrew with `.env` files #15787

MikeMcQuaid commented Jul 28, 2023

carlocab Jul 28, 2023

MikeMcQuaid Jul 28, 2023

carlocab Jul 28, 2023 •

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Allow configuring Homebrew with .env files #15787

Allow configuring Homebrew with .env files #15787

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MikeMcQuaid commented Jul 28, 2023

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MikeMcQuaid commented Aug 4, 2023

Allow configuring Homebrew with `.env` files #15787

Allow configuring Homebrew with `.env` files #15787

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