tfselect

README

TFselect

Inspired by warrensbox/terraform-switcher

The tfselect command line tool lets you switch between different versions of terraform. If you do not have a particular version of terraform installed, tfselect will download the version you desire. The installation is minimal and easy. Once installed, simply select the version you require from the dropdown and start using terraform.

Installation

tfselect is available for MacOS and Linux based operating systems (Windows experemetal).

Homebrew

Installation for MacOS/Linux is the easiest with Homebrew. If you do not have homebrew installed, click here.

brew install basti0nz/tap/tfselect

Linux

Installation for other linux operation systems.

curl -L https://raw.githubusercontent.com/basti0nz/tfselect/release/install.sh | bash

Build and install SNAP package

snap install snapcraft --classic

snap install multipass

snapcraft

snap install tfselect_*.snap --devmode --dangerous

tfselect -v

multipass stop snapcraft-tfselect && multipass delete snapcraft-tfselect && multipass purge

Get binary releases or install from source

Alternatively, you can get releases or install the binary from source here

How to use

Use dropdown menu to select version

1. You can switch between different versions of terraform by typing the command tfselect on your terminal.
2. Select the version of terraform you require by using the up and down arrow.
3. Hit Enter to select the desired version.

The most recently selected versions are presented at the top of the dropdown.

Supply version on command line

1. You can also supply the desired version as an argument on the command line.
2. For example, tfselect 0.13.5 for version 0.10.5 of terraform.
3. Hit Enter to switch.

Install latest version only

1. Install the latest stable version only.
2. Run tfselect -u or tfselect --latest.
3. Hit Enter to install.

Install latest implicit version for stable releases

1. Install the latest implicit stable version.
2. Ex: tfselect 0.13 downloads 0.13.6 (latest) version.
3. Hit Enter to install.

Use version.tf file

If a version.tf file with the terraform constrain is included in the current directory, it should automatically download or switch to that terraform version. For example, the following should automatically switch terraform to the lastest version:

terraform {
  required_version = ">= 0.12.9"

  required_providers {
    aws        = ">= 2.52.0"
    kubernetes = ">= 1.11.1"
  }
}

Use .tfselect.toml file (For non-admin - users with limited privilege on their computers)

This is similiar to using a .tfswitchrc file, but you can specify a custom binary path for your terraform installation

1. Create a custom binary path. Ex: mkdir /Users/basti0nz/bin (replace basti0nz with your username)
2. Add the path to your PATH. Ex: export PATH=$PATH:/Users/basti0nz/bin (add this to your bash profile or zsh profile)
3. Pass -b or --bin parameter with your custom path to install terraform. Ex: tfselect -b /Users/basti0nz/bin/terraform 0.10.8
4. Optionally, you can create a .tfselect.toml file in your home directory for global settings.
5. Your .tfselect.toml file should look like this:

bin = "/Users/versus/bin/terraform"
version = "0.11.3"

1. Run tfselect and it should automatically install the required terraform version in the specified binary path

Alternatively, you can generate .tfselect.toml in current directory just use tfselect --init or tfselect --init 0.13.2

Use .tfswitchrc file

1. Create a .tfswitchrc file containing the desired version
2. For example, echo "0.10.5" >> .tfswitchrc for version 0.10.5 of terraform
3. Run the command tfselect in the same directory as your .tfswitchrc

Use environment variable TFSELECT_PATH

1. Create a TFSELECT_PATH environment variable with your custom path to install terraform Ex: export TFSELECT_PATH=/Users/versus/bin/terraform
2. Run the command tfselect

Use environment variable TFSELECT_VERSION

1. Create a TFSELECT_PATH environment variable with your custom path to install terraform Ex: export TFSELECT_VERSION=0.13.5
2. Run the command tfselect

File .terraform-version may be used for compatibility with tfenv and other tools which use it

Use terragrunt.hcl file

If a terragrunt.hcl file with the terraform constrain is included in the current directory, it should automatically download or switch to that terraform version. For example, the following should automatically switch terraform to the lastest version:

terragrunt_version_constraint = ">= 0.26, < 0.27"
terraform_version_constraint  = ">= 0.13, < 0.14"
...

Example use case on a CI/CD agent

An agent host is scheduled to run multiple Terraform Plan/Apply tasks simultaneously from different repositories, which each contain different Terraform configurations, using different versions of Terraform.

With a regular symlink approach, they would have to be queued and run synchronously, as a version switch would have to be made between each run.

However, if the terraform binary (or symlink) is replaced with a script (example below) that catches the arguments sent to terraform, performs a tfselect using both the no-symlink and quiet flags, then catches the output from tfselect and uses the desired binary to run the specific task, this can be done dynamically with each run, in parallel.

This utilizes tfselect's brilliant ability to detect and install the required version, while allowing concurrency.

Example PoC script

#!/bin/bash

TF_DEFAULT_VERSION=0.13.2
TF_BIN_LOCATION=~/.terraform.versions

TF_SELECT=`tfselect -nq`
TF_DETECTED_VERSION=`echo "$TF_SELECT" | awk -F '\"|\"' '{print $2}' | grep "\S"`

echo "$TF_SELECT"

if [ "$TF_DETECTED_VERSION" == "" ]; then
    TF_DETECTED_VERSION=$TF_DEFAULT_VERSION
fi

TF_BIN="$TF_BIN_LOCATION/terraform_$TF_DETECTED_VERSION"

echo "Using version: $TF_DETECTED_VERSION"
echo ""

$TF_BIN "$@"

Suggestions and improvements are welcome.

Issues

Please open issues here: New Issue