brew doctor should not make changes

[machale]

Output of brew config

% brew config
HOMEBREW_VERSION: 4.0.3
ORIGIN: https://github.com/Homebrew/brew
HEAD: ba6d87eed9ce31f42fa2b33a4e6067d9cf17f13f
Last commit: 9 hours ago
Core tap origin: https://github.com/Homebrew/homebrew-core
Core tap HEAD: 45be88f3e5229a52c55589744a7ce583382566b8
Core tap last commit: 2 days ago
Core tap branch: master
Core tap JSON: 21 Feb 02:05 UTC
HOMEBREW_PREFIX: /usr/local
HOMEBREW_CASK_OPTS: []
HOMEBREW_GITHUB_API_TOKEN: set
HOMEBREW_MAKE_JOBS: 8
HOMEBREW_NO_ANALYTICS: set
Homebrew Ruby: 2.6.10 => /System/Library/Frameworks/Ruby.framework/Versions/2.6/usr/bin/ruby
CPU: octa-core 64-bit icelake
Clang: 14.0.0 build 1400
Git: 2.37.1 => /Library/Developer/CommandLineTools/usr/bin/git
Curl: 7.86.0 => /usr/bin/curl
macOS: 13.2.1-x86_64
CLT: 14.2.0.0.1.1668646533
Xcode: N/A

Output of brew doctor

% brew doctor
==> Downloading https://formulae.brew.sh/api/formula.json
######################################################################## 100.0%
Your system is ready to brew.

Description of issue

brew doctor generated the output above, one time. I can not repeat this, but I always thought brew doctor should make no changes to my system.

My main concern is brew doctor making changes, but as another data point, brew update did something similar - also only once.

% brew update
==> Downloading https://formulae.brew.sh/api/cask.json

Already up-to-date.

This occurred when I ran brew doctor approximately US EST 9:00pm on Monday February 20. I recently (February 18) upgraded macOS from 13.2 to 13.2.1, but this was not the first time since then that I ran brew doctor, so I don't suspect this is related to the macOS upgrade.

[machale]

Hmm. Right after submitting my post above, I tried brew doctor again and the behavior did repeat.

% brew doctor
==> Downloading https://formulae.brew.sh/api/formula.json
######################################################################## 100.0%
Your system is ready to brew.

A subsequent brew update did not repeat the behavior of downloading cask.json. And an additional attempt with brew doctor also did not repeat the behavior of dowbloading formula.json.

As of now, I don't have a pattern where this does, or does not, repeat.

[ZhongRuoyu]

brew doctor performs a series of checks, and some of them require the list of formulae (e.g. checking if any formulae installed are deprecated). So when you run brew doctor, the list of formulae will be downloaded from the API. Other than that, no changes will be made to your system.

as another data point, brew update did something similar - also only once.

brew update updates Homebrew itself, and also fetches the list of formulae from API.

As of now, I don't have a pattern where this does, or does not, repeat.

By default, brew checks the API every 450 seconds (7.5 minutes; see HOMEBREW_API_AUTO_UPDATE_SECS). In other words, it won't check the API again if it already did so less than 7.5 minutes ago.

[machale]

See also the reply below from @ZhongRuoyu and their link to the 4.0.0 release notes. GitHub doesn’t show an option to mark that reply as the answer, so I’m marking this one instead.

[machale]

Ah, interesting that brew doctor needs to download info like this. For brew update it makes sense to me. I just always figured brew doctor only checked local stuff - but I admit that was an assumption on my part.

Is it a recent change that brew doctor and brew update print a line about the download? Otherwise it's surprising I've never encountered these printed lines in many years of using Homebrew. (I probably average running brew doctor 2 or 3 times a week.)

[ZhongRuoyu]

Is it a recent change that brew doctor and brew update print a line about the download?

Yes. We recently switched to using a JSON API for installation (and querying) of formulae. You may read the 4.0.0 release notes for more details.