Intro

I use terraform and terragrunt to automate our AWS IT infrastructure.

Recently Hashicorp released major terraform upgrade.
The main point - upgrade from HCL 1 to HCL 2 (HCL is a language that terraform uses to describe IT infra setup.
There are a lot of useful features in HCL 2 so effort spent on upgrade from terraform 0.11 to 0.12 makes sense.

But to make the upgrade easier - it would be great to have terraform 0.11 and 0.12 side by side.
Then it would be possible to upgrade your terraform states one by one - till you upgrade them all!

Also as we use terragrunt we need to have:

0.18 version of it compatible with terraform 0.11
0.19 version of it compatible with terraform 0.12

side by side.

Prerequisites

brew package manager installed.
I use bash version 5.x, so if there will be any issues with bash scripts - check your bash version.

Upgrade from terraform 0.11 to 0.12 and from terragrunt 0.18 to 0.19

Upgrade process from terraform 0.11 to terraform 0.12 and from terragrunt 0.18 to terragrunt 0.19 is described on terraform and terragrunt websites:

You should just follow instructions to upgrade your terraform/terragrunt code.

Install terraform 0.11 on MacOS X

brew install terraform@0.11

Install terragrunt 0.18.x on MacOS X

sudo mkdir -p /opt/terragrunt_0.18/bin
cd /opt
chown -R youruser:staff terragrunt_0.18/bin
cd terragrunt_0.18/bin
wget https://github.com/gruntwork-io/terragrunt/releases/download/v0.18.7/terragrunt_darwin_amd64
mv terragrunt_darwin_amd64 terragrunt
chmod 755 terragrunt

Install terraform 0.12 on MacOS X

brew install terraform

Install terragrunt 0.19.x on MacOS X

brew install terragrunt

Configure switching between terraform 0.11/terragrunt 0.18 to terraform 0.12/terragrunt 0.19 and back

Now we need a convenient switching between to sets of terraform/terragrunt

mkdir ~/.bash.d

Add to ~/.bash_profile:


# if running bash
if [ -n "$BASH_VERSION" ]; then
  # Bash includes
  for include in ~/.bash.d/*.sh ; do source $include ; done
fi

Add to ~/.bash.d/init.sh:

append_to_PATH () {
    for d in "$@"; do
        d=$({ cd -- "$d" && { pwd -P || pwd; } } 2>/dev/null)  # canonicalize symbolic links
        if [ -z "$d" ]; then continue; fi  # skip nonexistent directory
        case ":$PATH:" in
            *":$d:"*) :;;
            *) PATH=$PATH:$d;;
        esac
    done
}

prepend_to_PATH () {
    for d in "$@"; do
        d=$({ cd -- "$d" && { pwd -P || pwd; } } 2>/dev/null)  # canonicalize symbolic links
        if [ -z "$d" ]; then continue; fi  # skip nonexistent directory
        case ":$PATH:" in
            *":$d:"*) :;;
            *) PATH=$d:$PATH;;
        esac
    done
}

remove_from_PATH () {
    FOLDERS_TO_REMOVE=`echo "$@" | sed 's/ /|/g'`
    PATH=$( echo ${PATH} | tr -s ":" "\n" | grep -vwE "(${FOLDERS_TO_REMOVE})" | tr -s "\n" ":" | sed "s/:$//" )
}

Add to ~/.bash.d/terraform.sh:

# Terraform 0.11&0.12 activation functions
t12 () {
    remove_from_PATH "/usr/local/Cellar/terraform@0.11/0.11.14/bin"
    remove_from_PATH "/opt/terragrunt_0.18/bin"
    export PATH=$PATH
}

t11 () {
    prepend_to_PATH "/usr/local/opt/terraform@0.11/bin"
    prepend_to_PATH "/opt/terragrunt_0.18/bin"
    export PATH=$PATH
}

after that:

source ~/.bash_profile

t11
terragrunt --version
terragrunt version v0.18.7
terraform --version
Terraform v0.11.14

Your version of Terraform is out of date! The latest version
is 0.12.3. You can update by downloading from www.terraform.io/downloads.html

t12
terragrunt --version
terragrunt version v0.19.6
terraform --version
Terraform v0.12.3

Have an easy migration :)

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Terraform 0.11 and 0.12 side-by-side