An explanation of how to install a specific version of a Homebrew formula.

brew-install-specific-formula.md

Install Previous Homebrew Formula

Sometimes you need to install a specific, older version of an existing Homebrew Formula. In this guide I am going to demonstrate how to install an older version of kubectl, but it can be generalized for an Formula.

The Kubernetes CLI is available as a Homebrew Formulae: https://formulae.brew.sh/formula/kubernetes-cli#default

At the time of writing, my only options to install kubectl via Homebrew are:

• brew install kubectl
  • Would install the default version of v1.29
• brew install kubectl@1.29 or brew install kubectl@1.28
• brew install kubernetes-cli@1.29 or brew install kubernetes-cli@1.28

But what if I wanted to install v1.27? Well, that is just slightly more involved and this guide will show you how to do just that.

1. Uninstall Existing Formula

First, uninstall the existing formula that you are looking to an install an older version of. In my case, I am going to run brew uninstall kubectl.

Michael ~ % kubectl version
Client Version: v1.29.0
Kustomize Version: v5.0.4-0.20230601165947-6ce0bf390ce3
The connection to the server localhost:8080 was refused - did you specify the right host or port?

Michael ~ % brew uninstall kubectl
Uninstalling /usr/local/Cellar/kubernetes-cli/1.29.0... (234 files, 60.3MB)

Michael ~ % which kubectl
kubectl not found

2. Find Formula .rb File

Homebrew keeps all of its Formula in GitHub. You now need to find the specific Formula and version that you want to install via the existing the .rb file. To do this:

1. Visit https://github.com/Homebrew/homebrew-core/tree/master/Formula
2. Navigate to the <formula>.rb file that matches the name of the formula that you want to install. (e.g. The kubernetes-cli .rb file is found here: https://github.com/Homebrew/homebrew-core/blob/master/Formula/k/kubernetes-cli.rb)
   • Note: The formula are in directories alphabaetically, so it should be easy to find your specific .rb file.
3. Click on the History button on the GitHub UI to view the commit history of your formula's .rb file. (e.g. The kubernetes-cli commit history is found at: https://github.com/Homebrew/homebrew-core/commits/master/Formula/k/kubernetes-cli.rb)
4. Find the commit that has a name of <formula-name>: update x.y.z bottle. (e.g. The kubernetes-cli commit for 1.27.4 is found at: https://github.com/Homebrew/homebrew-core/commit/ff26f5862313ea6bed2ce490266f8fd3f90ba86e)
5. Click on the *** button and select View file. (e.g. The file for the 1.27.4 kubernetes-cli is found at: https://github.com/Homebrew/homebrew-core/blob/ff26f5862313ea6bed2ce490266f8fd3f90ba86e/Formula/kubernetes-cli.rb)
6. Click on the Raw button.
7. Copy the URL and save it for the next step.

3. Install the Older Formula

1. Open a new terminal on your local machine.
2. Run curl -O <formula-rb-url> && brew install ./<formula-name>.rb.
   • Replace <formula-rb-url> with the URL found above.
   • Replace <formula-name> with the name of the Formula that you are installing.

Michael ~ % curl -O https://raw.githubusercontent.com/Homebrew/homebrew-core/ff26f5862313ea6bed2ce490266f8fd3f90ba86e/Formula/kubernetes-cli.rb && brew install ./kubernetes-cli.rb
  % Total    % Received % Xferd  Average Speed   Time    Time     Time  Current
                                 Dload  Upload   Total   Spent    Left  Speed
100  2342  100  2342    0     0  30779      0 --:--:-- --:--:-- --:--:-- 30815

==> Downloading https://formulae.brew.sh/api/formula.jws.json
################################################################################################################################# 100.0%
Error: Failed to load cask: ./kubernetes-cli.rb
Cask 'kubernetes-cli' is unreadable: wrong constant name #<Class:0x000000011627c650>
Warning: Treating ./kubernetes-cli.rb as a formula.
==> Downloading https://ghcr.io/v2/homebrew/core/kubernetes-cli/manifests/1.27.4
################################################################################################################################# 100.0%
==> Fetching kubernetes-cli
==> Downloading https://ghcr.io/v2/homebrew/core/kubernetes-cli/blobs/sha256:edc6ced447d957b366526978d201d962aba11bb2555cfa160012eb56d15
################################################################################################################################# 100.0%
Warning: kubernetes-cli 1.29.0 is available and more recent than version 1.27.4.
==> Pouring kubernetes-cli--1.27.4.ventura.bottle.tar.gz
==> Downloading https://formulae.brew.sh/api/cask.jws.json

==> Caveats
zsh completions have been installed to:
  /usr/local/share/zsh/site-functions
==> Summary
🍺  /usr/local/Cellar/kubernetes-cli/1.27.4: 230 files, 59.2MB

Michael ~ % kubectl version
WARNING: This version information is deprecated and will be replaced with the output from kubectl version --short.  Use --output=yaml|json to get the full version.
Client Version: version.Info{Major:"1", Minor:"27", GitVersion:"v1.27.4", GitCommit:"fa3d7990104d7c1f16943a67f11b154b71f6a132", GitTreeState:"clean", BuildDate:"2023-07-19T12:14:48Z", GoVersion:"go1.20.6", Compiler:"gc", Platform:"darwin/amd64"}
Kustomize Version: v5.0.1
The connection to the server localhost:8080 was refused - did you specify the right host or port?

3. Run rm <formula-name>.rb to delete the file that was created to download the Formula's .rb file.

That's it! You have installed an older version of an existing Formula. You can always use brew update <formula-name> to update your formula to the latest available version.