How to install brew using a shallow clone (especially useful in CI systems)

Question

The brew installer does a git clone of some very large repositories, which is slow.

It doesn't use:

• shallow clones because GitHub asked them not to so-as to avoid brew update being slower c.f. https://github.com/Homebrew/install/issues/541, and
• partial clones are not supported yet c.f. https://github.com/Homebrew/brew/issues/13188

In a CI environment where brew update is not needed, how can the brew installer be forced to use a shallow clone to speed up the operation?

Answer 1

The installer can be hacked to use shallow clone. Then an error occurs when the installer tries to run brew update. So the steps are fetch the installer script, force using shallow clone, and remove the use of brew update.

wget -c https://raw.githubusercontent.com/Homebrew/install/HEAD/install.sh
sed -i 's:"git" "fetch":"git" "fetch" "--depth" "1":' ./install.sh
sed -i '/"update" "--force"/d' ./install.sh

When doing this, be sure to use HOMEBREW_NO_AUTO_UPDATE=1 and do not use brew update.

To do the install, run

HOMEBREW_NO_AUTO_UPDATE=1 bash ./install.sh