README.md

terraform-aws-sns-to-cloudwatch-logs-lambda

terraform-aws-sns-to-cloudwatch-logs-lambda is a Terraform module to provision a Lambda Function which routes SNS messages to CloudWatch Logs

Exception: if using var.aws_region to specify deployment region, use version = "2.0.1", until you can switch to provider aliases and explicit provider passing.

Terraform Module Features

This Module allows simple and rapid deployment

• Creates Lambda function, Lambda Layer, IAM Policies, Triggers, and Subscriptions
• Creates (or use existing) SNS Topic, CloudWatch Log Group and Log Group Stream
• Options:
  • Create CloudWatch Event to prevent Function hibernation
  • Set Log Group retention period
• Python function editable in repository and in Lambda UI
  • Python dependencies packages in Lambda Layers zip
• Optionally create custom Lambda Layer zip using build-lambda-layer-python
  • Enables adding/changing dependencies
  • Enables compiling for different version of Python
• Breaking Changes in 3.0.0 - required to enable new Terraform 0.13 module arguments for_each, count, and depends_on
  • The module's internal AWS provider block has been removed
  • var.aws_region has been removed and can't be used to set a target region
  • By default, modules inherit the region of the calling module's Provider
  • To specify alternate regions, use provider aliases and expicit provider passing
  • Additional information on module considerations can be found in the docs for Provider Configuration in Modules with 0.13

SNS to CloudWatch Logs Features

This Lambda Function forwards subject & body of SNS messages to CloudWatch Log Group Stream

• Enhances the value of CloudWatch Logs by enabling easy entry creation from any service, function and script that can send SNS notifications
• Enables cloud-init, bootstraps and functions to easily write log entries to a centralized CloudWatch Log
• Simplifies troubleshooting of solutions with decentralized logic
  • scripts and functions spread across instances, Lambda and services
• Easily add instrumentation to scripts: aws sns publish --topic-arn $TOPIC_ARN --message $LOG_ENTRY
  • Use with IAM instance policy requires --region $AWS_REGION parameter

Usage

module "sns_logger" {
  source            = "robertpeteuil/sns-to-cloudwatch-logs-lambda/aws"
  version           = "3.0.1"     # Use with Terraform >= 0.12 (including 0.13)
  # version           = "1.0.1"   # Latest version for Terraform <= 0.11

  sns_topic_name    = "projectx-logging"
  log_group_name    = "projectx"
  log_stream_name   = "script-logs"
}

NOTE: Make sure you are using version pinning to avoid unexpected changes when the module is updated.

Required Inputs

Name	Description	Type	Default	Required
sns_topic_name	Name of SNS Topic to be logged by Gateway	string	-	yes
log_group_name	Name of CloudWatch Log Group	string	-	yes
log_stream_name	Name of CloudWatch Log Stream	string	-	yes

Optional Inputs

Name	Description	Type	Default	Required
create_sns_topic	Create new SNS topic	string	true	no
create_log_group	Create new log group	string	true	no
create_log_stream	Create new log stream	string	true	no
log_group_retention_days	Log Group retention (days)	string	0 (forever)	no
lambda_func_name	Name for Lambda Function	string	dynamically calculated	no
lambda_description	Lambda Function Description	string	Route SNS messages to CloudWatch Logs	no
lambda_tags	Mapping of Tags to assign to Lambda function	map	{}	no
lambda_publish_func	Publish Lambda Function	string	false	no
lambda_runtime	Lambda runtime for Function	string	python3.11	no
lambda_timeout	Function time-out (seconds)	string	3	no
lambda_mem_size	Function RAM assigned (MB)	string	128	no
create_warmer_event	Create CloudWatch trigger event to prevent hibernation	string	false	no

Requirements

Name	Version
terraform	>= 1.0
aws	>= 2.31

Providers

Name	Version
archive	n/a
aws	>= 2.31

Modules

No modules.

Resources

Name	Type
aws_cloudwatch_event_rule.warmer	resource
aws_cloudwatch_event_target.warmer	resource
aws_cloudwatch_log_group.sns_logged_item_group	resource
aws_cloudwatch_log_stream.sns_logged_item_stream	resource
aws_iam_role.lambda_cloudwatch_logs	resource
aws_iam_role_policy.lambda_cloudwatch_logs_polcy	resource
aws_lambda_function.sns_cloudwatchlog	resource
aws_lambda_layer_version.logging_base	resource
aws_lambda_permission.sns_cloudwatchlog_multi	resource
aws_lambda_permission.warmer_multi	resource
aws_sns_topic.sns_log_topic	resource
aws_sns_topic_subscription.lambda	resource
archive_file.lambda_function	data source
aws_cloudwatch_log_group.sns_logged_item_group	data source
aws_iam_policy_document.lambda_cloudwatch_logs	data source
aws_iam_policy_document.lambda_cloudwatch_logs_policy	data source
aws_sns_topic.sns_log_topic	data source

Inputs

Name	Description	Type	Default	Required
create_log_group	Boolean flag that determines if log group, 'log_group_name' is created. If 'false' it uses an existing group of that name.	bool	true	no
create_log_stream	Boolean flag that determines if log stream, 'log_stream_name' is created. If 'false' it uses an existing stream of that name.	bool	true	no
create_sns_topic	Boolean flag that determines if SNS topic, 'sns_topic_name' is created. If 'false' it uses an existing topic of that name.	bool	true	no
create_warmer_event	Boolean flag that determines if a CloudWatch Trigger event is created to prevent Lambda function from suspending.	bool	false	no
lambda_description	Description to assign to Lambda Function.	string	""	no
lambda_func_name	Name to assign to Lambda Function.	string	"SNStoCloudWatchLogs"	no
lambda_mem_size	Amount of RAM (in MB) assigned to the function. The default (and minimum) is 128MB, and the maximum is 3008MB.	number	128	no
lambda_publish_func	Boolean flag that determines if Lambda function is published as a version.	bool	false	no
lambda_runtime	Lambda runtime to use for the function.	string	"python3.11"	no
lambda_tags	A mapping of tags to assign to Lambda Function.	map	{}	no
lambda_timeout	Number of seconds that the function can run before timing out. The AWS default is 3s and the maximum runtime is 5m	number	3	no
log_group_name	Name of CloudWatch Log Group created or used (if previously created).	string	n/a	yes
log_group_retention_days	Number of days to retain data in the log group (0 = always retain).	number	0	no
log_stream_name	Name of CloudWatch Log Stream created or used (if previously created). If using an existing stream it must exist in the Log group specified in 'log_group_name'.	string	n/a	yes
sns_topic_name	Name of SNS Topic logging to CloudWatch Log.	string	n/a	yes

Outputs

Name	Description
cloudwatch_event_rule_arn	ARN of CloudWatch Trigger Event created to prevent hibernation.
lambda_arn	ARN of created Lambda Function.
lambda_iam_role_arn	Lambda IAM Role ARN.
lambda_iam_role_id	Lambda IAM Role ID.
lambda_last_modified	The date Lambda Function was last modified.
lambda_name	Name assigned to Lambda Function.
lambda_version	Latest published version of Lambda Function.
log_group_arn	ARN of CloudWatch Log Group.
log_group_name	Name of CloudWatch Log Group.
log_stream_arn	ARN of CloudWatch Log Stream.
log_stream_name	Name of CloudWatch Log Stream.
sns_topic_arn	ARN of SNS Topic logging to CloudWatch Log.
sns_topic_name	Name of SNS Topic logging to CloudWatch Log.