Module: `tfstate-backend`

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:

Forced server-side encryption at rest for the S3 bucket
S3 bucket versioning to allow for Terraform state recovery in the case of accidental deletions and human errors
State locking and consistency checking via DynamoDB table to prevent concurrent operations
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: https://github.com/terraform-providers/terraform-provider-aws/issues/629

Usage

Create

Follow this procedure just once to create your deployment.

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.

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

In main.tf, change the terraform_state_backend module arguments as follows:

 module "terraform_state_backend" {
   # ...
   terraform_backend_config_file_path = ""
   force_destroy                      = true
 }

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.
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.
terraform destroy. This deletes all resources in your deployment.
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"
}

Variables

Required Variables

Optional Variables

acl (string) optional

The canned ACL to apply to the S3 bucket

Default value: "private"

arn_format (string) optional

ARN format to be used. May be changed to support deployment in GovCloud/China regions.

Default value: "arn:aws"

billing_mode (string) optional

DynamoDB billing mode

Default value: "PAY_PER_REQUEST"

block_public_acls (bool) optional

Whether Amazon S3 should block public ACLs for this bucket

Default value: true

block_public_policy (bool) optional

Whether Amazon S3 should block public bucket policies for this bucket

Default value: true

bucket_enabled (bool) optional

Whether to create the S3 bucket.

Default value: true

bucket_ownership_enforced_enabled (bool) optional

Set bucket object ownership to "BucketOwnerEnforced". Disables ACLs.

Default value: true

deletion_protection_enabled (bool) optional

A boolean that enables deletion protection for DynamoDB table

Default value: false

dynamodb_enabled (bool) optional

Whether to create the DynamoDB table.

Default value: true

dynamodb_table_name (string) optional

Override the name of the DynamoDB table which defaults to using module.dynamodb_table_label.id

Default value: null

enable_point_in_time_recovery (bool) optional

Enable DynamoDB point-in-time recovery

Default value: true

enable_public_access_block (bool) optional

Enable Bucket Public Access Block

Default value: true

force_destroy (bool) optional

A boolean that indicates the S3 bucket can be destroyed even if it contains objects. These objects are not recoverable

Default value: false

ignore_public_acls (bool) optional

Whether Amazon S3 should ignore public ACLs for this bucket

Default value: true

kms_master_key_id (string) optional

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.

Default value: null

logging optional

Destination (S3 bucket name and prefix) for S3 Server Access Logs for the S3 bucket.

Type:

list(object({
target_bucket = string
target_prefix = string
}))

Default value: [ ]

mfa_delete (bool) optional

A boolean that indicates that versions of S3 objects can only be deleted with MFA. ( Terraform cannot apply changes of this value; https://github.com/terraform-providers/terraform-provider-aws/issues/629 )

Default value: false

permissions_boundary (string) optional

ARN of the policy that is used to set the permissions boundary for the IAM replication role

Default value: ""

prevent_unencrypted_uploads (bool) optional

Prevent uploads of unencrypted objects to S3

Default value: true

profile (string) optional

AWS profile name as set in the shared credentials file

Default value: ""

read_capacity (number) optional

DynamoDB read capacity units when using provisioned mode

Default value: 5

restrict_public_buckets (bool) optional

Whether Amazon S3 should restrict public bucket policies for this bucket

Default value: true

role_arn (string) optional

The role to be assumed

Default value: ""

s3_bucket_name (string) optional

S3 bucket name. If not provided, the name will be generated from the context by the label module.

Default value: ""

s3_replica_bucket_arn (string) optional

The ARN of the S3 replica bucket (destination)

Default value: ""

s3_replication_enabled (bool) optional

Set this to true and specify s3_replica_bucket_arn to enable replication

Default value: false

s3_state_lock_enabled (bool) optional

Whether to create the S3 bucket.

Default value: false

source_policy_documents (list(string)) optional

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.

Default value: [ ]

sse_encryption (string) optional

The server-side encryption algorithm to use.
Valid values are AES256, aws:kms, and aws:kms:dsse.

Default value: "AES256"

terraform_backend_config_file_name (string) optional

(Deprecated) Name of terraform backend config file to generate

Default value: "terraform.tf"

terraform_backend_config_file_path (string) optional

(Deprecated) Directory for the terraform backend config file, usually .. The default is to create no file.

Default value: ""

terraform_backend_config_template_file (string) optional

(Deprecated) The path to the template used to generate the config file

Default value: ""

terraform_state_file (string) optional

The path to the state file inside the bucket

Default value: "terraform.tfstate"

terraform_version (string) optional

The minimum required terraform version

Default value: null

write_capacity (number) optional

DynamoDB write capacity units when using provisioned mode

Default value: 5

Context Variables

The following variables are defined in the context.tf file of this module and part of the terraform-null-label pattern.

additional_tag_map (map(string)) optional

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.

Required: No

Default value: { }

attributes (list(string)) optional

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.

Required: No

Default value: [ ]

context (any) optional

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.

Required: No

Default value:

{
  "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
}

delimiter (string) optional

Delimiter to be used between ID elements.
Defaults to - (hyphen). Set to "" to use no delimiter at all.

Required: No

Default value: null

descriptor_formats (any) optional

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).

Required: No

Default value: { }

enabled (bool) optional

Set to false to prevent the module from creating any resources
Required: No

Default value: null

environment (string) optional

ID element. Usually used for region e.g. 'uw2', 'us-west-2', OR role 'prod', 'staging', 'dev', 'UAT'
Required: No

Default value: null

id_length_limit (number) optional

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.

Required: No

Default value: null

label_key_case (string) optional

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.

Required: No

Default value: null

label_order (list(string)) optional

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.

Required: No

Default value: null

label_value_case (string) optional

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.

Required: No

Default value: null

labels_as_tags (set(string)) optional

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.

Required: No

Default value:

[
  "default"
]

name (string) optional

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.

Required: No

Default value: null

namespace (string) optional

ID element. Usually an abbreviation of your organization name, e.g. 'eg' or 'cp', to help ensure generated IDs are globally unique
Required: No

Default value: null

regex_replace_chars (string) optional

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.

Required: No

Default value: null

stage (string) optional

ID element. Usually used to indicate role, e.g. 'prod', 'staging', 'source', 'build', 'test', 'deploy', 'release'
Required: No

Default value: null

tags (map(string)) optional

Additional tags (e.g. {'BusinessUnit': 'XYZ'}).
Neither the tag keys nor the tag values will be modified by this module.

Required: No

Default value: { }

tenant (string) optional

ID element (Rarely used, not included by default). A customer identifier, indicating who this instance of a resource is for
Required: No

Default value: null

Outputs

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

Dependencies

Requirements

terraform, version: >= 1.1.0
aws, version: >= 4.9.0
local, version: >= 2.0
time, version: >= 0.7.1

Providers

aws, version: >= 4.9.0
local, version: >= 2.0
time, version: >= 0.7.1

Modules

Name	Version	Source	Description
`bucket_label`	0.25.0	`cloudposse/label/null`	n/a
`dynamodb_table_label`	0.25.0	`cloudposse/label/null`	n/a
`replication_label`	0.25.0	`cloudposse/label/null`	n/a
`this`	0.25.0	`cloudposse/label/null`	n/a

Resources

The following resources are used by this module:

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_object_lock_configuration.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)

Data Sources

The following data sources are used by this module:

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)

Module: tfstate-backend

Usage​

Create​

Destroy​

Bucket Replication (Disaster Recovery)​

Variables​

Required Variables​

Optional Variables​

Context Variables​

Outputs​

Dependencies​

Requirements​

Providers​

Modules​

Resources​

Data Sources​

Module: `tfstate-backend`

Usage

Create

Destroy

Bucket Replication (Disaster Recovery)

Variables

Required Variables

Optional Variables

Context Variables

Outputs

Dependencies

Requirements

Providers

Modules

Resources

Data Sources