At Gruntwork, we work with many customers and environments and find it’s necessary to switch among multiple versions of Terraform daily.

I happen to work on a Mac and find the Homebrew project to be an invaluable tool to help me install software. The biggest complaint I have about Homebrew, though, is that they don’t make it easy to install older versions of software.

Luckily, through some experimentation, I was able to come up with the procedure outlined below to use Homebrew to manage multiple versions of Terraform and to be able to switch among them easily.

[NOTE: YMMV with this particular workaround and I don’t know if this is ‘officially supported’ by the Homebrew project]

Let’s start by cloning the Homebrew project to our local machine.

$ git clone git@github.com:Homebrew/homebrew-core.git
$ cd homebrew-core

Next, find the Git commit id that added the version of Terraform we’re interested in installing. For this example, we’ll look to install Terraform version 0.11.8.

$ git log master -- Formula/terraform.rb

commit 49017817fb34b76fdc81f33665fdd7661fe5e558 (HEAD)
Author: BrewTestBot 
Date:   Tue Oct 23 23:17:42 2018 +0000

terraform: update 0.11.10 bottle.

commit 252d11cbf0d63aad22d043ef490b996b7a1c115c
Author: James Gregory 
Date:   Wed Oct 24 09:28:21 2018 +1100

terraform 0.11.10

Closes #33324.

Signed-off-by: commitay 

commit 12c25cb2fc4b51bd0271f5d1fd00c6f500863966
Author: BrewTestBot 
Date:   Sat Oct 20 02:56:24 2018 +0000

terraform: update 0.11.9 bottle.

commit 7373f02c6f028904ac5c7f8d94290a44f911a736
Author: FX Coudert 
Date:   Fri Oct 19 22:03:27 2018 +0200

terraform 0.11.9

Closes #33186.

Signed-off-by: commitay 

commit 3507fce2ba1f36cc371fe888fd093bf5aa79981d
Author: BrewTestBot 
Date:   Mon Aug 20 10:47:28 2018 +0000

terraform: update 0.11.8 bottle.

<***remaining output truncated***>

We can see commit 3507fce2ba1f36cc371fe888fd093bf5aa79981d is the one that last updated 0.11.8, so we’ll use that commit.

$ git checkout 3507fce2ba1f36cc371fe888fd093bf5aa79981d
$ cd Formula
$ brew unpin terraform (I'll explain this further below)
$ brew unlink terraform
$ brew install terraform.rb

It’s as simple as that, and we now have Terraform 0.11.8 installed on our machine!

Now that we have multiple versions of Terraform installed, there are a few other commands you’ll want to get familiar with.

The brew switch command will allow you to switch among versions of Terraform that are installed on your system.

$ brew switch terraform 0.11.8
$ terraform --version
Terraform v0.11.8

$ brew switch terraform 0.11.14
$ terraform --version
Terraform v0.11.14

The brew pin command will prevent Homebrew from updating/upgrading your version of Terraform when you run the brew upgrade command. I would strongly suggest pinning Terraform because otherwise, the brew upgrade command will remove all older versions of Terraform from your system.

$ brew pin terraform
$ brew info terraform

terraform: stable 0.11.14 (bottled), HEAD [pinned at 0.11.14]
Tool to build, change, and version infrastructure
https://www.terraform.io/
Conflicts with:
tfenv (because tfenv symlinks terraform binaries)
/usr/local/Cellar/terraform/0.11.8 (6 files, 88.9MB) *
Poured from bottle on 2019-05-21 at 15:07:13
/usr/local/Cellar/terraform/0.11.14 (6 files, 42.4MB)
Poured from bottle on 2019-05-21 at 15:02:18
From: https://github.com/Homebrew/homebrew-core/blob/master/Formula/terraform.rb
==> Dependencies
Build: go ✔, gox ✔
==> Options
--HEAD
Install HEAD version
==> Analytics
install: 18,754 (30 days), 64,658 (90 days), 200,703 (365 days)
install_on_request: 17,871 (30 days), 61,462 (90 days), 189,133 (365 days)
build_error: 0 (30 days)

Finally, if you’d like to see all of the versions of Terraform installed on your system, the easiest way I’ve found is by looking at the Homebrew Cellar directory.

$ ls /usr/local/Cellar/terraform

drwxrwxr-x  88 matt  admin  2816 May 21 14:50 ..
drwxr-xr-x   4 matt  staff   128 May 21 15:02 .
drwxr-xr-x   8 matt  staff   256 May 21 15:07 0.11.14
drwxr-xr-x   8 matt  staff   256 May 21 15:09 0.11.8

I hope this(relatively) simple procedure helps you easily install and manage the various versions of Terraform (and other packages) on your system!