transmit GCP monitoring alerting messages via Pub/Sub with Terraform

To transmit GCP monitoring alerting messages via Pub/Sub with Terraform, you can use the following steps:

1. Create a Pub/Sub topic to receive the alert messages:

resource "google_pubsub_topic" "pubsub_topic" {
  name = "my-pubsub-topic"
}

1. Create a Cloud Function to process the alert messages and publish them to the Pub/Sub topic:

resource "google_cloud_function" "pubsub_forward_function" {
  name = "my-pubsub-forward-function"
  runtime = "python37"
  trigger_http = false
  source_archive_bucket = "my-bucket"
  source_archive_object = "my-function.zip"

  handler = "my_function.handler"

  environment_variables = {
    PUBSUB_TOPIC = google_pubsub_topic.pubsub_topic.name
  }
}

1. Create a google_monitoring_alert_policy resource to configure the alert and specify the Cloud Function as the notification channel:

resource "google_monitoring_alert_policy" "pubsub_alert" {
  name = "pubsub_alert"
  display_name = "Pub/Sub alert"
  description = "Alert when the number of messages received by a subscription exceeds a threshold."

  conditions {
    metric_name = "pubsub.subscription.messages_received"
    resource.type = "pubsub.subscription"
    resource.labels.subscription = "my-subscription"

    trigger {
      count = 100
      duration = "1m"
      type = "COUNT"
    }
  }

  notification_channels = [google_cloud_function.pubsub_forward_function.name]
}

1. Create a Terraform configuration file that contains the above resources and deploy it using the terraform apply command.

Once the Terraform configuration has been deployed, the alert policy will be configured to send notifications to the Cloud Function when the specified conditions are met. The Cloud Function will then process the alert message and publish it to the Pub/Sub topic.

You can then subscribe to the Pub/Sub topic and process the alert messages in any way that you need. For example, you could use a Cloud Function to send the alert messages to a Slack channel or to a PagerDuty incident.

Here is an example of a complete Terraform configuration file for transmitting GCP monitoring alerting messages via Pub/Sub:

resource "google_pubsub_topic" "pubsub_topic" {
  name = "my-pubsub-topic"
}

resource "google_cloud_function" "pubsub_forward_function" {
  name = "my-pubsub-forward-function"
  runtime = "python37"
  trigger_http = false
  source_archive_bucket = "my-bucket"
  source_archive_object = "my-function.zip"

  handler = "my_function.handler"

  environment_variables = {
    PUBSUB_TOPIC = google_pubsub_topic.pubsub_topic.name
  }
}

resource "google_monitoring_alert_policy" "pubsub_alert" {
  name = "pubsub_alert"
  display_name = "Pub/Sub alert"
  description = "Alert when the number of messages received by a subscription exceeds a threshold."

  conditions {
    metric_name = "pubsub.subscription.messages_received"
    resource.type = "pubsub.subscription"
    resource.labels.subscription = "my-subscription"

    trigger {
      count = 100
      duration = "1m"
      type = "COUNT"
    }
  }

  notification_channels = [google_cloud_function.pubsub_forward_function.name]
}

To deploy this configuration, you can use the following command:

terraform apply

Once the configuration has been deployed, you can test the alert by publishing some messages to the my-subscription subscription. If the number of messages received by the subscription exceeds the threshold, you should receive an alert message on the Pub/Sub topic