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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 0.13 or higher

If you need Terraform 0.12, you should use version 2.x of this module and contribute changes to the tf-0.12 branch.

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"
  db_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.identifier
  db_instance_class = "db.t2.micro"
  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"
  db_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.identifier
  db_instance_class = "db.t2.micro"
  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