handle Serverless provisioning from Terraform

conditional-removal.sh

#!/bin/bash

# $1 is the name of the repository
# $2 is the optional tag of the repository

REMOVE=$(node should-remove.js microservice)
if [[ $REMOVE == "true" ]]; then
  git clone https://github.com/owner/$1.git
  cd $1/
  if [ "$2" != "" ]; then
    git checkout tags/$2 -b $2
  fi
  yarn install
  yarn serverless remove
  cd ..
  rm -rf $1/
fi

deploy.sh

#!/bin/bash

# $1 is the name of the repository
# $2 is the optional tag of the repository

git clone https://github.com/owner/$1.git
cd $1/
if [ "$2" != "" ]; then
  git checkout tags/$2 -b $2
fi
yarn install
yarn serverless deploy
cd ..
rm -rf $1/

main.tf

...
locals { microservice_version = "v1.9.0" }
resource "null_resource" "microservice" {
  # either do not define count or set count = 0 for soft deletion
  depends_on = [null_resource.some_other_resource]
  triggers   = { version = "${local.microservice_version}" }
  provisioner "local-exec" {
    # deploy from serverless
    command     = "bash deploy.sh microservice ${local.microservice_version}"
    # required environment variables
    environment = { ... }
  }
  provisioner "local-exec" {
    # deploy from serverless
    command     = "bash conditional-removal.sh microservice ${local.microservice_version}"
    when        = destroy
    # required environment variables
    environment = { ... }
  }
}

should-remove.js

const fs = require('fs')
const path = require('path')
const hcltojson = require('hcl-to-json')
const config = fs.readFileSync(path.join(__dirname, 'main.tf'), { encoding: 'utf8' })

// $1 is the name of the repository
const [repo] = process.argv.slice(2)

const { resource } = hcltojson(config)
const { null_resource } = resource
const definition = null_resource[repo]
const count = definition.hasOwnProperty('count') ? definition.count : 1

// not marked for deletion
if (count === 1) console.log(false)
// count should either be undefined or set to 0
else if (count > 1) throw new Error('this script cannot handle multiple count of the same null_resource')
// has been marked for deletion
else console.log(true)

Sadly I tested to create a Terraform module locally but even if the script currently executes and does the job, this way is clearly stated as deprecated and might stop to work in future versions of Terraform.

My current version is :

Terraform v0.12.19
+ provider.null v2.1.2

whether using variables.tf :

or piping them through environment :