Terraform Module for AWS RDS Cloudwatch Alarms

This Terraform module manages Cloudwatch Alarms for an RDS instance. It does NOT create or manage RDS, only Metric Alarms.

Requires:

• AWS Provider
• Terraform 0.12

Alarms Created

Alarms Always Created (default values can be overridden):

• CPU Utilization above 90%
• Disk queue depth above 64
• Disk space less than 10 GB
• EBS Volume burst balance less than 100
• Freeable memory below 256 MB
• Swap usage above 256 MB
• Anomalous connection count

If the instance type is a T-Series instance type (automatically determind), the following alarms are also created:

• CPU Credit Balance below 100

If the database engine is any of postgres type (configured with var.engine), then the following alarms are also created:

• Maximum used transaction IDs over 1,000,000,000 [reference]

Estimated Operating Cost: $ 1.00 / month

• $ 0.10 / month for Metric Alarms (7x)
• $ 0.30 / month for Anomaly Alarm (1x)

Example

resource "aws_db_instance" "default" {
  allocated_storage    = 10
  storage_type         = "gp2"
  engine               = "mysql"
  engine_version       = "5.7"
  instance_class       = "db.t2.micro"
  identifier_prefix    = "rds-server-example"
  name                 = "my-db"
  username             = "foo"
  password             = "bar"
  parameter_group_name = "default.mysql5.7"
  apply_immediately    = "true"
  skip_final_snapshot  = "true"
}

resource "aws_sns_topic" "default" {
  name_prefix = "my-premade-topic"
}

module "aws-rds-alarms" {
  source         = "lorenzoaiello/rds-alarms/aws"
  version        = "x.y.z"
  db_instance_id = aws_db_instance.default.id
  actions_alarm  = [aws_sns_topic.default.arn]
  actions_ok     = [aws_sns_topic.default.arn]
}

This above can pair very nicely for example with an module which creates an SNS topic which sends your alerts into Slack. For example:

resource "aws_db_instance" "default" {
  allocated_storage    = 10
  storage_type         = "gp2"
  engine               = "mysql"
  engine_version       = "5.7"
  instance_class       = "db.t2.micro"
  identifier_prefix    = "rds-server-example"
  name                 = "my-db"
  username             = "foo"
  password             = "bar"
  parameter_group_name = "default.mysql5.7"
  apply_immediately    = "true"
  skip_final_snapshot  = "true"
}

module "notify_slack" {
  source  = "terraform-aws-modules/notify-slack/aws"
  version = "~> 4.0"

  sns_topic_name = "slack-topic"

  slack_webhook_url = "https://hooks.slack.com/services/AAA/BBB/CCC"
  slack_channel     = "aws-notification"
  slack_username    = "reporter"
}

module "aws-rds-alarms" {
  source         = "lorenzoaiello/rds-alarms/aws"
  version        = "x.y.z"
  db_instance_id = aws_db_instance.default.id
  actions_alarm  = [module.sns_to_slack.this_slack_topic_arn]
  actions_ok     = [module.sns_to_slack.this_slack_topic_arn]
}

Variables

Name	Description	Type	Default	Required
actions_alarm	A list of actions to take when alarms are triggered. Will likely be an SNS topic for event distribution.	list	[]	no
actions_ok	A list of actions to take when alarms are cleared. Will likely be an SNS topic for event distribution.	list	[]	no
anomaly_period	The number of seconds that make each evaluation period for anomaly detection.	string	"600"	no
anomaly_band_width	The width of the anomaly band detection. Higher numbers means less sensitive	string	"2"	no
db_instance_id	RDS Instance ID	string	n/a	yes
engine	The RDS engine being used. Used for database engine specific alarms	string	""	no
evaluation_period	The evaluation period over which to use when triggering alarms.	string	"5"	no
prefix	Alarm Name Prefix	string	""	no
statistic_period	The number of seconds that make each statistic period.	string	"60"	no
tags	Tags to attach to each alarm	map(string)	{}	no
db_instance_class	The rds instance-class, e.g. db.t3.medium	string		yes
cpu_utilization_too_high_threshold	Alarm threshold for the 'highCPUUtilization' alarm	string	"90"	no
cpu_credit_balance_too_low_threshold	Alarm threshold for the 'lowCPUCreditBalance' alarm	string	"100"	no
disk_queue_depth_too_high_threshold	Alarm threshold for the 'highDiskQueueDepth' alarm	string	"64"	no
disk_free_storage_space_too_low_threshold	Alarm threshold for the 'lowFreeStorageSpace' alarm (in bytes)	string	"10000000000"	no
disk_burst_balance_too_low_threshold	Alarm threshold for the 'lowEBSBurstBalance' alarm	string	"100"	no
maximum_used_transaction_ids_too_high_threshold	Alarm threshold for the 'maximumUsedTransactionIDs' alarm	string	"1000000000"	no
memory_freeable_too_low_threshold	Alarm threshold for the 'lowFreeableMemory' alarm (in bytes)	string	"256000000"	no
memory_swap_usage_too_high_threshold	Alarm threshold for the 'highSwapUsage' alarm (in bytes)	string	"256000000"	no
create_high_cpu_alarm	Whether or not to create the high cpu alarm	bool	true	no
create_low_cpu_credit_alarm	Whether or not to create the low cpu credit alarm	bool	true	no
create_high_queue_depth_alarm	Whether or not to create the high queue depth alarm	bool	true	no
create_low_disk_space_alarm	Whether or not to create the low disk space alarm	bool	true	no
create_low_disk_burst_alarm	Whether or not to create the low disk burst alarm	bool	true	no
create_low_memory_alarm	Whether or not to create the low memory free alarm	bool	true	no
create_swap_alarm	Whether or not to create the high swap usage alarm	bool	true	no
create_anomaly_alarm	Whether or not to create the fairly noisy anomaly alarm	bool	true	no

Outputs

Name	Description
alarm_connection_count_anomalous	The CloudWatch Metric Alarm resource block for anomalous Connection Count
alarm_cpu_credit_balance_too_low	The CloudWatch Metric Alarm resource block for low CPU Credit Balance
alarm_cpu_utilization_too_high	The CloudWatch Metric Alarm resource block for high CPU Utilization
alarm_disk_burst_balance_too_low	The CloudWatch Metric Alarm resource block for low Disk Burst Balance
alarm_disk_free_storage_space_too_low	The CloudWatch Metric Alarm resource block for low Free Storage Space
alarm_disk_queue_depth_too_high	The CloudWatch Metric Alarm resource block for high Disk Queue Depth
alarm_memory_freeable_too_low	The CloudWatch Metric Alarm resource block for low Freeable Memory
alarm_memory_swap_usage_too_high	The CloudWatch Metric Alarm resource block for high Memory Swap Usage
alarm_maximum_used_transaction_ids_too_high	The CloudWatch Metric Alarm resource block for postgres' Transaction ID Wraparound