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Terraform module that provision an S3 bucket to store the `terraform.tfstate` file and a DynamoDB table to lock the state file to prevent concurrent modifications and state corruption.

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Terraform module to provision an S3 bucket to store terraform.tfstate file and a DynamoDB table to lock the state file to prevent concurrent modifications and state corruption.

The module supports the following:

  1. Forced server-side encryption at rest for the S3 bucket
  2. S3 bucket versioning to allow for Terraform state recovery in the case of accidental deletions and human errors
  3. State locking and consistency checking via DynamoDB table to prevent concurrent operations
  4. DynamoDB server-side encryption

https://www.terraform.io/docs/backends/types/s3.html

NOTE: The operators of the module (IAM Users) must have permissions to create S3 buckets and DynamoDB tables when performing terraform plan and terraform apply

NOTE: This module cannot be used to apply changes to the mfa_delete feature of the bucket. Changes regarding mfa_delete can only be made manually using the root credentials with MFA of the AWS Account where the bucket resides. Please see: hashicorp/terraform-provider-aws#629

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Usage

Create

Follow this procedure just once to create your deployment.

  1. Add the terraform_state_backend module to your main.tf file. The comment will help you remember to follow this procedure in the future:

    # You cannot create a new backend by simply defining this and then
    # immediately proceeding to "terraform apply". The S3 backend must
    # be bootstrapped according to the simple yet essential procedure in
    # https://github.com/cloudposse/terraform-aws-tfstate-backend#usage
    module "terraform_state_backend" {
      source = "cloudposse/tfstate-backend/aws"
      # Cloud Posse recommends pinning every module to a specific version
      # version     = "x.x.x"
      namespace  = "eg"
      stage      = "test"
      name       = "terraform"
      attributes = ["state"]
    
      terraform_backend_config_file_path = "."
      terraform_backend_config_file_name = "backend.tf"
      force_destroy                      = false
    }
    
    # Your Terraform configuration
    module "another_module" {
      source = "....."
    }

    Module inputs terraform_backend_config_file_path and terraform_backend_config_file_name control the name of the backend definition file. Note that when terraform_backend_config_file_path is empty (the default), no file is created.

  2. terraform init. This downloads Terraform modules and providers.

  3. terraform apply -auto-approve. This creates the state bucket and DynamoDB locking table, along with anything else you have defined in your *.tf file(s). At this point, the Terraform state is still stored locally.

    Module terraform_state_backend also creates a new backend.tf file that defines the S3 state backend. For example:

    backend "s3" {
      region         = "us-east-1"
      bucket         = "< the name of the S3 state bucket >"
      key            = "terraform.tfstate"
      dynamodb_table = "< the name of the DynamoDB locking table >"
      profile        = ""
      role_arn       = ""
      encrypt        = true
    }

    Henceforth, Terraform will also read this newly-created backend definition file.

  4. terraform init -force-copy. Terraform detects that you want to move your Terraform state to the S3 backend, and it does so per -auto-approve. Now the state is stored in the S3 bucket, and the DynamoDB table will be used to lock the state to prevent concurrent modification.

This concludes the one-time preparation. Now you can extend and modify your Terraform configuration as usual.

Destroy

Follow this procedure to delete your deployment.

  1. In main.tf, change the terraform_state_backend module arguments as follows:
     module "terraform_state_backend" {
       # ...
       terraform_backend_config_file_path = ""
       force_destroy                      = true
     }
  2. terraform apply -target module.terraform_state_backend -auto-approve. This implements the above modifications by deleting the backend.tf file and enabling deletion of the S3 state bucket.
  3. terraform init -force-copy. Terraform detects that you want to move your Terraform state from the S3 backend to local files, and it does so per -auto-approve. Now the state is once again stored locally and the S3 state bucket can be safely deleted.
  4. terraform destroy. This deletes all resources in your deployment.
  5. Examine local state file terraform.tfstate to verify that it contains no resources.

s3-bucket-with-terraform-state

Bucket Replication (Disaster Recovery)

To enable S3 bucket replication in this module, set s3_replication_enabled to true and populate s3_replica_bucket_arn with the ARN of an existing bucket.

module "terraform_state_backend" {
  source = "cloudposse/tfstate-backend/aws"
  # Cloud Posse recommends pinning every module to a specific version
  # version     = "x.x.x"
  namespace  = "eg"
  stage      = "test"
  name       = "terraform"
  attributes = ["state"]

  terraform_backend_config_file_path = "."
  terraform_backend_config_file_name = "backend.tf"
  force_destroy                      = false

  s3_replication_enabled = true
  s3_replica_bucket_arn  = "arn:aws:s3:::eg-test-terraform-tfstate-replica"
}

Important

In Cloud Posse's examples, we avoid pinning modules to specific versions to prevent discrepancies between the documentation and the latest released versions. However, for your own projects, we strongly advise pinning each module to the exact version you're using. This practice ensures the stability of your infrastructure. Additionally, we recommend implementing a systematic approach for updating versions to avoid unexpected changes.

Makefile Targets

Available targets:

  help                                Help screen
  help/all                            Display help for all targets
  help/short                          This help short screen
  lint                                Lint terraform code

Requirements

Name Version
terraform >= 1.1.0
aws >= 4.9.0
local >= 2.0
time >= 0.7.1

Providers

Name Version
aws >= 4.9.0
local >= 2.0
time >= 0.7.1

Modules

Name Source Version
bucket_label cloudposse/label/null 0.25.0
dynamodb_table_label cloudposse/label/null 0.25.0
replication_label cloudposse/label/null 0.25.0
this cloudposse/label/null 0.25.0

Resources

Name Type
aws_dynamodb_table.with_server_side_encryption resource
aws_iam_policy.replication resource
aws_iam_role.replication resource
aws_iam_role_policy_attachment.replication resource
aws_s3_bucket.default resource
aws_s3_bucket_acl.default resource
aws_s3_bucket_logging.default resource
aws_s3_bucket_ownership_controls.default resource
aws_s3_bucket_policy.default resource
aws_s3_bucket_public_access_block.default resource
aws_s3_bucket_replication_configuration.replication resource
aws_s3_bucket_server_side_encryption_configuration.default resource
aws_s3_bucket_versioning.default resource
local_file.terraform_backend_config resource
time_sleep.wait_for_aws_s3_bucket_settings resource
aws_iam_policy_document.aggregated_policy data source
aws_iam_policy_document.bucket_policy data source
aws_iam_policy_document.replication data source
aws_iam_policy_document.replication_sts data source
aws_region.current data source

Inputs

Name Description Type Default Required
acl The canned ACL to apply to the S3 bucket string "private" no
additional_tag_map Additional key-value pairs to add to each map in tags_as_list_of_maps. Not added to tags or id.
This is for some rare cases where resources want additional configuration of tags
and therefore take a list of maps with tag key, value, and additional configuration.
map(string) {} no
arn_format ARN format to be used. May be changed to support deployment in GovCloud/China regions. string "arn:aws" no
attributes ID element. Additional attributes (e.g. workers or cluster) to add to id,
in the order they appear in the list. New attributes are appended to the
end of the list. The elements of the list are joined by the delimiter
and treated as a single ID element.
list(string) [] no
billing_mode DynamoDB billing mode string "PAY_PER_REQUEST" no
block_public_acls Whether Amazon S3 should block public ACLs for this bucket bool true no
block_public_policy Whether Amazon S3 should block public bucket policies for this bucket bool true no
bucket_enabled Whether to create the S3 bucket. bool true no
bucket_ownership_enforced_enabled Set bucket object ownership to "BucketOwnerEnforced". Disables ACLs. bool true no
context Single object for setting entire context at once.
See description of individual variables for details.
Leave string and numeric variables as null to use default value.
Individual variable settings (non-null) override settings in context object,
except for attributes, tags, and additional_tag_map, which are merged.
any
{
"additional_tag_map": {},
"attributes": [],
"delimiter": null,
"descriptor_formats": {},
"enabled": true,
"environment": null,
"id_length_limit": null,
"label_key_case": null,
"label_order": [],
"label_value_case": null,
"labels_as_tags": [
"unset"
],
"name": null,
"namespace": null,
"regex_replace_chars": null,
"stage": null,
"tags": {},
"tenant": null
}
no
deletion_protection_enabled A boolean that enables deletion protection for DynamoDB table bool false no
delimiter Delimiter to be used between ID elements.
Defaults to - (hyphen). Set to "" to use no delimiter at all.
string null no
descriptor_formats Describe additional descriptors to be output in the descriptors output map.
Map of maps. Keys are names of descriptors. Values are maps of the form
{<br/> format = string<br/> labels = list(string)<br/>}
(Type is any so the map values can later be enhanced to provide additional options.)
format is a Terraform format string to be passed to the format() function.
labels is a list of labels, in order, to pass to format() function.
Label values will be normalized before being passed to format() so they will be
identical to how they appear in id.
Default is {} (descriptors output will be empty).
any {} no
dynamodb_enabled Whether to create the DynamoDB table. bool true no
dynamodb_table_name Override the name of the DynamoDB table which defaults to using module.dynamodb_table_label.id string null no
enable_point_in_time_recovery Enable DynamoDB point-in-time recovery bool true no
enable_public_access_block Enable Bucket Public Access Block bool true no
enabled Set to false to prevent the module from creating any resources bool null no
environment ID element. Usually used for region e.g. 'uw2', 'us-west-2', OR role 'prod', 'staging', 'dev', 'UAT' string null no
force_destroy A boolean that indicates the S3 bucket can be destroyed even if it contains objects. These objects are not recoverable bool false no
id_length_limit Limit id to this many characters (minimum 6).
Set to 0 for unlimited length.
Set to null for keep the existing setting, which defaults to 0.
Does not affect id_full.
number null no
ignore_public_acls Whether Amazon S3 should ignore public ACLs for this bucket bool true no
kms_master_key_id AWS KMS master key ID used for the SSE-KMS encryption.
This can only be used when you set the value of sse_algorithm as aws:kms.
string null no
label_key_case Controls the letter case of the tags keys (label names) for tags generated by this module.
Does not affect keys of tags passed in via the tags input.
Possible values: lower, title, upper.
Default value: title.
string null no
label_order The order in which the labels (ID elements) appear in the id.
Defaults to ["namespace", "environment", "stage", "name", "attributes"].
You can omit any of the 6 labels ("tenant" is the 6th), but at least one must be present.
list(string) null no
label_value_case Controls the letter case of ID elements (labels) as included in id,
set as tag values, and output by this module individually.
Does not affect values of tags passed in via the tags input.
Possible values: lower, title, upper and none (no transformation).
Set this to title and set delimiter to "" to yield Pascal Case IDs.
Default value: lower.
string null no
labels_as_tags Set of labels (ID elements) to include as tags in the tags output.
Default is to include all labels.
Tags with empty values will not be included in the tags output.
Set to [] to suppress all generated tags.
Notes:
The value of the name tag, if included, will be the id, not the name.
Unlike other null-label inputs, the initial setting of labels_as_tags cannot be
changed in later chained modules. Attempts to change it will be silently ignored.
set(string)
[
"default"
]
no
logging Destination (S3 bucket name and prefix) for S3 Server Access Logs for the S3 bucket.
list(object({
target_bucket = string
target_prefix = string
}))
[] no
mfa_delete A boolean that indicates that versions of S3 objects can only be deleted with MFA. ( Terraform cannot apply changes of this value; hashicorp/terraform-provider-aws#629 ) bool false no
name ID element. Usually the component or solution name, e.g. 'app' or 'jenkins'.
This is the only ID element not also included as a tag.
The "name" tag is set to the full id string. There is no tag with the value of the name input.
string null no
namespace ID element. Usually an abbreviation of your organization name, e.g. 'eg' or 'cp', to help ensure generated IDs are globally unique string null no
permissions_boundary ARN of the policy that is used to set the permissions boundary for the IAM replication role string "" no
prevent_unencrypted_uploads Prevent uploads of unencrypted objects to S3 bool true no
profile AWS profile name as set in the shared credentials file string "" no
read_capacity DynamoDB read capacity units when using provisioned mode number 5 no
regex_replace_chars Terraform regular expression (regex) string.
Characters matching the regex will be removed from the ID elements.
If not set, "/[^a-zA-Z0-9-]/" is used to remove all characters other than hyphens, letters and digits.
string null no
restrict_public_buckets Whether Amazon S3 should restrict public bucket policies for this bucket bool true no
role_arn The role to be assumed string "" no
s3_bucket_name S3 bucket name. If not provided, the name will be generated from the context by the label module. string "" no
s3_replica_bucket_arn The ARN of the S3 replica bucket (destination) string "" no
s3_replication_enabled Set this to true and specify s3_replica_bucket_arn to enable replication bool false no
source_policy_documents List of IAM policy documents (in JSON format) that are merged together into the generated S3 bucket policy.
Statements must have unique SIDs.
Statement having SIDs that match policy SIDs generated by this module will override them.
list(string) [] no
sse_encryption The server-side encryption algorithm to use.
Valid values are AES256, aws:kms, and aws:kms:dsse.
string "AES256" no
stage ID element. Usually used to indicate role, e.g. 'prod', 'staging', 'source', 'build', 'test', 'deploy', 'release' string null no
tags Additional tags (e.g. {'BusinessUnit': 'XYZ'}).
Neither the tag keys nor the tag values will be modified by this module.
map(string) {} no
tenant ID element _(Rarely used, not included by default)_. A customer identifier, indicating who this instance of a resource is for string null no
terraform_backend_config_file_name (Deprecated) Name of terraform backend config file to generate string "terraform.tf" no
terraform_backend_config_file_path (Deprecated) Directory for the terraform backend config file, usually .. The default is to create no file. string "" no
terraform_backend_config_template_file (Deprecated) The path to the template used to generate the config file string "" no
terraform_state_file The path to the state file inside the bucket string "terraform.tfstate" no
terraform_version The minimum required terraform version string "1.0.0" no
write_capacity DynamoDB write capacity units when using provisioned mode number 5 no

Outputs

Name Description
dynamodb_table_arn DynamoDB table ARN
dynamodb_table_id DynamoDB table ID
dynamodb_table_name DynamoDB table name
s3_bucket_arn S3 bucket ARN
s3_bucket_domain_name S3 bucket domain name
s3_bucket_id S3 bucket ID
s3_replication_role_arn The ARN of the IAM Role created for replication, if enabled.
terraform_backend_config Rendered Terraform backend config file

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License

License

Preamble to the Apache License, Version 2.0

Complete license is available in the LICENSE file.

Licensed to the Apache Software Foundation (ASF) under one
or more contributor license agreements.  See the NOTICE file
distributed with this work for additional information
regarding copyright ownership.  The ASF licenses this file
to you under the Apache License, Version 2.0 (the
"License"); you may not use this file except in compliance
with the License.  You may obtain a copy of the License at

  https://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing,
software distributed under the License is distributed on an
"AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
KIND, either express or implied.  See the License for the
specific language governing permissions and limitations
under the License.

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