asmtal / tf_aws_tfstate_bucket

create buckets for terraform tfstate files and set cross-region replication.

terraform state buckets

This is an independent terraform module which need be run before any other terraform commands.

The reason is, we need a s3 bucket to be ready and save terraform tfstate files when initialize a Terraform configuration

Features

1. terraform configuration files to create terraform state buckets
2. create source bucket and destination buckets
3. set cross-region replication on the source bucket.

Set source and destination regions.

Update source and destination regions in variable.tf

S3 bucket name must be globally unique

Currently I use aws account alias name as part of bucket name, you should set postfix to make sure the bucket name is globally unique.

Update bucket postfix name in variable.tf

What is and is not replicated.

What Is and Is Not Replicated

Recommend to enable Amazon S3-Managed Encryption Keys (SSE-S3), but not customer-provided (SSE-C) or AWS KMS–managed encryption (SSE-KMS) keys. Because:

Objects created with server-side encryption using either customer-provided (SSE-C) or AWS KMS–managed encryption (SSE-KMS) keys are not replicated.

Sample backend configuration

terraform init \
-backend=true \
-backend-config="bucket=tf-state" \
-backend-config="key=terraform.tfstate" \
-backend-config="region=eu-west-1" \
-backend-config="acl=bucket-owner-full-control" \
-backend-config="encrypt=1"

Import state

If the tfstate bucket exists, please use below command to import its state after you inited the backend.

terraform import aws_s3_bucket.bucket <exist_bucket_name>

Usage

terraform init
terraform plan
terraform apply

Manually copy the state file to s3 bucket.

After you run terraform plan and terraform apply, a new state file terraform.tfstate is generated, you need manually copy the file to source bucket.

To make sure replicate works, you should see the file has been replicated to bucket <source_bucket>-destination

Reference:

How to Set Up Cross-Region Replication

initialize a Terraform configuration