DevOps: What is Terraform State Management?

1# Backend configuration
2terraform {
3  backend "s3" {
4    bucket         = "my-terraform-state"
5    key            = "prod/terraform.tfstate"
6    region         = "us-west-2"
7    dynamodb_table = "terraform-locks"
8    encrypt        = true
9  }
10}
11
12# State commands
13# terraform state list
14# terraform state show aws_instance.web
15# terraform state mv aws_instance.old aws_instance.new
16# terraform state rm aws_instance.orphan
17# terraform import aws_instance.existing i-1234567890abcdef0
18
19# Workspaces
20# terraform workspace new dev
21# terraform workspace select prod
22# terraform workspace list
23
24# Data sources for remote state
25data "terraform_remote_state" "vpc" {
26  backend = "s3"
27  config = {
28    bucket = "my-terraform-state"
29    key    = "shared/vpc/terraform.tfstate"
30    region = "us-west-2"
31  }
32}
33
34resource "aws_instance" "web" {
35  subnet_id = data.terraform_remote_state.vpc.outputs.public_subnet_id
36}