Health Checks

A Route53 health check pings a url dozens of times from different locations around the world; this example shows how to setup a health check and attach a CloudWatch Alarm.

info

Health checks can only be provisioned in the us-east region. If you wish to connect the alarms to an SNS topic you will need to provision a us-east SNS topic specifically for these alarms.

Set the variables

The enable_alerts variable is used to turn on/off notifications per environment.

variable "webapp_fqdn" {  type        = string  description = "The URL of the web app, used for health checks"}variable "enable_alerts" {  type        = bool  description = "When enabled CloudWatch alarm events are sent to the Alerts SNS Topic"  default     = false}

Create the health check

resource "aws_route53_health_check" "webapp_health_check" {  reference_name    = "webapp-health-check"  failure_threshold = 5  fqdn              = var.webapp_fqdn  port              = 443  request_interval  = "30"  resource_path     = var.webapp_health_check_path  type              = "HTTPS_STR_MATCH"  search_string     = "Ship shape and Bristol fashion"}

Create the alarm

resource "aws_cloudwatch_metric_alarm" "webapp_health" {  namespace           = "AWS/Route53"  alarm_name          = "${aws_ecs_service.service.name}-webapp-health-alarm"  metric_name         = "HealthCheckStatus"  comparison_operator = "LessThanOrEqualToThreshold"  evaluation_periods  = "1"  period              = "60"  statistic           = "Minimum"  threshold           = "0"  treat_missing_data  = "breaching"  alarm_description   = "This metric monitors webapp health"  provider            = aws.us-east  alarm_actions       = var.enable_alerts == true ? [aws_sns_topic.sns_service_alerts.arn] : []  ok_actions          = var.enable_alerts == true ? [aws_sns_topic.sns_service_alerts.arn] : []
  dimensions = {    HealthCheckId = aws_route53_health_check.webapp_health_check.id  }}