Medium - Mate Terraform and Serverless

main.tf

module "sls_user" {
  source = "./microservice"
  microservice_version = "1.0.0"
}
module "sls_product" {
  source = "./microservice"
  microservice_version = "1.0.0"
  # microservice_active = false
}

module.tf

# WARNING : this file should be located in ./microservice/module.tf

# variable name 'version' is already reserved by Terraform, hence the alternate name here
variable "microservice_version" {
  type          = string
}
variable "microservice_active" {
  type          = bool
  default       = true
}
resource "null_resource" "microservice" {
  triggers      = { version = "${var.microservice_version}" }
  count         = var.microservice_active ? 1 : 0
  provisioner "local-exec" {
    # here you would write the command to deploy with Serverless
    command     = "echo \"install ${var.microservice_version} && serverless deploy\""
  }
  provisioner "local-exec" {
    # here you would write the command to remove with Serverless
    command     = "echo \"serverless remove\""
    when        = destroy
  }
}

package.json

{
  "name": "medium-mate-terraform-with-serverless",
  "version": "1.0.0",
  "main": "index.js",
  "author": "Romain KELIFA",
  "license": "MIT",
  "scripts": {
    "tf:init": "terraform init",
    "tf:plan": "terraform plan -out terraform.plan && terraform show -json terraform.plan > terraform.plan.json",
    "tf:taint": "bash taint.sh",
    "tf:apply": "terraform apply --auto-approve",
    "tf:clean": "rm -f terraform.plan terraform.plan.json",
    "deploy": "yarn tf:init && yarn tf:plan && yarn tf:taint && yarn tf:apply"
  }
}

should-taint.js

const fs = require('fs')
const path = require('path')

const plan = fs.readFileSync(path.join(__dirname, 'terraform.plan.json'), { encoding: 'utf8' })
const modules = fs.readFileSync(path.join(__dirname, '.terraform', 'modules', 'modules.json'), { encoding: 'utf8' })

const is = {}
is.serverless = key => JSON.parse(modules)
.Modules
.filter(({ Source }) => Source === './microservice') // define Source according to your module source
.find(({ Key }) => Key === key)

const taint = JSON.parse(plan)
.resource_changes
.filter(({ module_address }) => is.serverless(module_address.split('.')[1])) // filter the serverless modules
.filter(({ change }) => (change.actions.includes('create') && change.actions.includes('delete'))) // output of `triggers`
.map(({ address }) => address)

taint.forEach(address => console.log(address))

taint.sh

#!/usr/bin/env node

for ADDRESS in $(node should-taint.js)
do
  terraform taint $ADDRESS
done