feat: two examples for sharing data

03-terraform-outputs-across-stacks/using-resource-data/README.md

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+# Example of sharing data between stacks with Terramate
+
+This example shows dynamic generation of the Terraform backend allowing us to use a `terraform_remote_state` data block that references a different stack by ID. Combined with using tags for ordering, this means we can easily reorganise our stacks without any breakage.
+
+To try this example you will need to edit the file `backend.tm.hcl` and change the bucket name to an existing bucket you have access to.

03-terraform-outputs-across-stacks/using-resource-data/backend.tm.hcl

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+globals {
+  aws_region   = "us-west-2"
+  name         = "terramate-example-data-sharing"
+  state_bucket = "CHANGE-THIS"
+}
+
+# generates the backend.tf in each stack
+generate_hcl "_backend.tf" {
+  content {
+    terraform {
+      backend "s3" {
+        bucket  = global.state_bucket
+        key     = "state-files/stacks/${terramate.stack.id}/terraform.state"
+        region  = global.aws_region
+        encrypt = true
+      }
+
+      required_providers {
+        aws = {
+          source  = "hashicorp/aws"
+          version = "~> 5.0"
+        }
+      }
+    }
+
+    provider "aws" {
+      region = global.aws_region
+    }
+  }
+}

03-terraform-outputs-across-stacks/using-resource-data/stacks/EC2/_backend.tf

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+// TERRAMATE: GENERATED AUTOMATICALLY DO NOT EDIT
+
+terraform {
+  backend "s3" {
+    bucket  = "CHANGE-THIS"
+    encrypt = true
+    key     = "state-files/stacks/9d2b1b15-0ea2-45cd-9573-90fe67bdafda/terraform.state"
+    region  = "us-west-2"
+  }
+  required_providers {
+    aws = {
+      source  = "hashicorp/aws"
+      version = "~> 5.0"
+    }
+  }
+}
+provider "aws" {
+  region = "us-west-2"
+}

03-terraform-outputs-across-stacks/using-resource-data/stacks/EC2/_data.tf

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+// TERRAMATE: GENERATED AUTOMATICALLY DO NOT EDIT
+
+data "aws_subnet" "vpc" {
+  filter {
+    name = "tag:Name"
+    values = [
+      "terramate-example-data-sharing",
+    ]
+  }
+}

03-terraform-outputs-across-stacks/using-resource-data/stacks/EC2/main.tf

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+data "aws_ami" "ubuntu" {
+  most_recent = true
+
+  filter {
+    name   = "name"
+    values = ["ubuntu/images/hvm-ssd/ubuntu-focal-20.04-amd64-server-*"]
+  }
+
+  filter {
+    name   = "virtualization-type"
+    values = ["hvm"]
+  }
+
+  owners = ["099720109477"] # Canonical
+}
+
+resource "aws_instance" "web" {
+  ami           = data.aws_ami.ubuntu.id
+  subnet_id     = data.terraform_remote_state.vpc.outputs.subnet_id
+  instance_type = "t3.micro"
+
+  tags = {
+    Name = "HelloWorld"
+  }
+}

03-terraform-outputs-across-stacks/using-resource-data/stacks/EC2/remote-state.tm.hcl

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+generate_hcl "_data.tf" {
+  content {
+    data "aws_subnet" "vpc" {
+      filter {
+        name = "tag:Name"
+        values = [
+          global.name,
+        ]
+      }
+    }
+  }
+}

03-terraform-outputs-across-stacks/using-resource-data/stacks/EC2/stack.tm.hcl

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+stack {
+  name        = "ec2"
+  description = "ec2"
+  id          = "9d2b1b15-0ea2-45cd-9573-90fe67bdafda"
+  after       = ["tag:vpc"]
+}

03-terraform-outputs-across-stacks/using-resource-data/stacks/VPC/_backend.tf

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+// TERRAMATE: GENERATED AUTOMATICALLY DO NOT EDIT
+
+terraform {
+  backend "s3" {
+    bucket  = "CHANGE-THIS"
+    encrypt = true
+    key     = "state-files/stacks/e4790733-c105-4870-bdf7-9ab67fcc655c/terraform.state"
+    region  = "us-west-2"
+  }
+  required_providers {
+    aws = {
+      source  = "hashicorp/aws"
+      version = "~> 5.0"
+    }
+  }
+}
+provider "aws" {
+  region = "us-west-2"
+}

03-terraform-outputs-across-stacks/using-resource-data/stacks/VPC/_vpc-and-subnet.tf

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+// TERRAMATE: GENERATED AUTOMATICALLY DO NOT EDIT
+
+resource "aws_vpc" "main" {
+  cidr_block       = "10.0.0.0/16"
+  instance_tenancy = "default"
+  tags = {
+    Name = "terramate-example-data-sharing"
+  }
+}
+resource "aws_subnet" "main" {
+  cidr_block = "10.0.1.0/24"
+  tags = {
+    Name = "terramate-example-data-sharing"
+  }
+  vpc_id = aws_vpc.main.id
+}

03-terraform-outputs-across-stacks/using-resource-data/stacks/VPC/stack.tm.hcl

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+stack {
+  name        = "vpc"
+  description = "vpc"
+  id          = "e4790733-c105-4870-bdf7-9ab67fcc655c"
+  tags        = ["vpc"]
+}

03-terraform-outputs-across-stacks/using-resource-data/stacks/VPC/subnet.tm.hcl

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+generate_hcl "_vpc-and-subnet.tf" {
+  content {
+    resource "aws_vpc" "main" {
+      cidr_block       = "10.0.0.0/16"
+      instance_tenancy = "default"
+
+      tags = {
+        Name = global.name
+      }
+    }
+    resource "aws_subnet" "main" {
+      vpc_id     = aws_vpc.main.id
+      cidr_block = "10.0.1.0/24"
+
+      tags = {
+        Name = global.name
+      }
+    }
+  }
+}