Terraform module to create AWS VPC Flow logs backed by S3.

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Introduction

The module will create:

• S3 bucket with server side encryption
• KMS key to encrypt flow logs files in the bucket
• Optional VPC Flow Log backed by the S3 bucket (this can be disabled, e.g. in multi-account environments if you want to create an S3 bucket in one account and VPC Flow Logs in different accounts)

Usage

For a complete example, see examples/complete.

For automated tests of the complete example using bats and Terratest (which tests and deploys the example on Datadog), see test.

  module "vpc" {
    source  = "cloudposse/vpc/aws"
    version = "0.18.0"

    namespace  = "eg"
    stage      = "test"
    name       = "flowlogs"
    cidr_block = "172.16.0.0/16"
  }

  module "flow_logs" {
    source  = "cloudposse/vpc-flow-logs-s3-bucket/aws"
    version = "0.8.0"

    namespace  = "eg"
    stage      = "test"
    name       = "flowlogs"

    vpc_id = module.vpc.vpc_id
  }

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	>= 1.3.0
aws	>= 4.9.0

Providers

Name	Version
aws	>= 4.9.0

Modules

Name	Source	Version
bucket_name	cloudposse/label/null	0.25.0
kms_key	cloudposse/kms-key/aws	0.12.2
s3_log_storage_bucket	cloudposse/s3-log-storage/aws	1.4.3
this	cloudposse/label/null	0.25.0

Resources

Name	Type
aws_flow_log.default	resource
aws_caller_identity.current	data source
aws_iam_policy_document.bucket	data source
aws_iam_policy_document.kms	data source
aws_partition.current	data source

Inputs

Name	Description	Type	Default	Required
access_log_bucket_name	Name of the S3 bucket where S3 access log will be sent to	string	""	no
access_log_bucket_prefix	Prefix to prepend to the current S3 bucket name, where S3 access logs will be sent to	string	"logs/"	no
acl	The canned ACL to apply. We recommend log-delivery-write for compatibility with AWS services	string	"log-delivery-write"	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
allow_ssl_requests_only	Set to true to require requests to use Secure Socket Layer (HTTPS/SSL). This will explicitly deny access to HTTP requests	bool	true	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
bucket_key_enabled	Set this to true to use Amazon S3 Bucket Keys for SSE-KMS, which may reduce the number of AWS KMS requests. For more information, see: https://docs.aws.amazon.com/AmazonS3/latest/userguide/bucket-key.html	bool	true	no
bucket_name	Bucket name. If not provided, the bucket will be created with a name generated from the context.	string	""	no
bucket_notifications_enabled	Send notifications for the object created events. Used for 3rd-party log collection from a bucket	bool	false	no
bucket_notifications_prefix	Prefix filter. Used to manage object notifications	string	""	no
bucket_notifications_type	Type of the notification configuration. Only SQS is supported.	string	"SQS"	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
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
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
expiration_days	(Deprecated, use lifecycle_configuration_rules instead) Number of days after which to expunge the objects	number	null	no
flow_log_enabled	Enable/disable the Flow Log creation. Useful in multi-account environments where the bucket is in one account, but VPC Flow Logs are in different accounts	bool	true	no
force_destroy	A boolean that indicates all objects should be deleted from the bucket so that the bucket can be destroyed without error. These objects are not recoverable	bool	false	no
glacier_transition_days	(Deprecated, use lifecycle_configuration_rules instead) Number of days after which to move the data to the Glacier Flexible Retrieval storage tier	number	null	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
kms_key_arn	ARN (or alias) of KMS that will be used for s3 bucket encryption.	string	""	no
kms_policy_source_json	Additional IAM policy document that can optionally be merged with default created KMS policy	string	""	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
lifecycle_configuration_rules	A list of lifecycle V2 rules	list(object({ enabled = bool id = string abort_incomplete_multipart_upload_days = number # filter_and is the and configuration block inside the filter configuration. # This is the only place you should specify a prefix. filter_and = optional(object({ object_size_greater_than = optional(number) # integer >= 0 object_size_less_than = optional(number) # integer >= 1 prefix = optional(string) tags = optional(map(string)) })) expiration = optional(object({ date = optional(string) # string, RFC3339 time format, GMT days = optional(number) # integer > 0 expired_object_delete_marker = optional(bool) })) noncurrent_version_expiration = optional(object({ newer_noncurrent_versions = optional(number) # integer > 0 noncurrent_days = optional(number) # integer >= 0 })) transition = optional(list(object({ date = optional(string) # string, RFC3339 time format, GMT days = optional(number) # integer >= 0 storage_class = string # string/enum, one of GLACIER, STANDARD_IA, ONEZONE_IA, INTELLIGENT_TIERING, DEEP_ARCHIVE, GLACIER_IR. })), []) noncurrent_version_transition = optional(list(object({ newer_noncurrent_versions = optional(number) # integer >= 0 noncurrent_days = optional(number) # integer >= 0 storage_class = string # string/enum, one of GLACIER, STANDARD_IA, ONEZONE_IA, INTELLIGENT_TIERING, DEEP_ARCHIVE, GLACIER_IR. })), []) }))	[]	no
lifecycle_prefix	(Deprecated, use lifecycle_configuration_rules instead) Prefix filter. Used to manage object lifecycle events	string	null	no
lifecycle_rule_enabled	DEPRECATED: Use lifecycle_configuration_rules instead. When true, configures lifecycle events on this bucket using individual (now deprecated) variables. When false, lifecycle events are not configured using individual (now deprecated) variables, but lifecycle_configuration_rules still apply. When null, lifecycle events are configured using individual (now deprecated) variables only if lifecycle_configuration_rules is empty.	bool	null	no
lifecycle_tags	(Deprecated, use lifecycle_configuration_rules instead) Tags filter. Used to manage object lifecycle events	map(string)	null	no
log_format	The fields to include in the flow log record, in the order in which they should appear.	string	null	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
noncurrent_version_expiration_days	(Deprecated, use lifecycle_configuration_rules instead) Specifies when non-current object versions expire (in days)	number	null	no
noncurrent_version_transition_days	(Deprecated, use lifecycle_configuration_rules instead) Specifies (in days) when noncurrent object versions transition to Glacier Flexible Retrieval	number	null	no
object_lock_configuration	A configuration for S3 object locking.	object({ mode = string # Valid values are GOVERNANCE and COMPLIANCE. days = number years = number })	null	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
s3_object_ownership	Specifies the S3 object ownership control. Valid values are ObjectWriter, BucketOwnerPreferred, and BucketOwnerEnforced." Default of BucketOwnerPreferred is for backwards compatibility. Recommended setting is BucketOwnerEnforced, which will be used if you pass in null.	string	"BucketOwnerPreferred"	no
stage	ID element. Usually used to indicate role, e.g. 'prod', 'staging', 'source', 'build', 'test', 'deploy', 'release'	string	null	no
standard_transition_days	(Deprecated, use lifecycle_configuration_rules instead) Number of days to persist in the standard storage tier before moving to the infrequent access tier	number	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
traffic_type	The type of traffic to capture. Valid values: ACCEPT, REJECT, ALL	string	"ALL"	no
versioning_enabled	Enable object versioning, keeping multiple variants of an object in the same bucket	bool	false	no
vpc_id	VPC ID to create flow logs for	string	null	no

Outputs

Name	Description
bucket_arn	Bucket ARN
bucket_domain_name	FQDN of bucket
bucket_id	Bucket Name (aka ID)
bucket_notifications_sqs_queue_arn	Notifications SQS queue ARN
bucket_prefix	Bucket prefix configured for lifecycle rules
flow_log_arn	Flow Log ARN
flow_log_id	Flow Log ID
kms_alias_arn	KMS Alias ARN
kms_alias_name	KMS Alias name
kms_key_arn	KMS Key ARN
kms_key_id	KMS Key ID

Related Projects

Check out these related projects.

• terraform-aws-vpc - Terraform Module that defines a VPC with public/private subnets across multiple AZs with Internet Gateways
• CIS AWS Foundations Benchmark in the AWS Cloud - CIS Benchmarks are consensus-based configuration guidelines developed by experts in US government, business, industry, and academia to help organizations assess and improve security

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