A Cloud Function that will parse GKE cluster upgrade notifications (and upgrade available notifications) and send them to Slack.

This is a Python script meant to run in a GCP Cloud Function.

The two files here main.py and requirements.txt can be compiled into a zip file called main.py.zip and placed in a GCS bucket for retrieval by the function. Optionally, you can configure a source repo.

You'll need a Slack application with an incoming webhook token that has permission to post in whichever channel you'd like to receive these notifications.

You're free to tweak this as needed to make it work for your use case.

• SEND_UPGRADE_AVAILABLE_NOTIFICATIONS - if set to enabled, notifications will be sent regarding UpgradeAvailableEvent types. This can be verbose and annoying, so it is configurable.
• SLACK_WEBHOOK_URL - should contain the webhook for sending to Slack.

• You must have a Pub/Sub topic available to handle notifications from a given GKE cluster:

resource "google_pubsub_topic" "gke_cluster_upgrade_notifications" {
  name    = "gke-cluster-upgrade-notifications"
  project = "example-1234"

  labels = {
    ...
  }

  message_storage_policy {
    allowed_persistence_regions = [
      "region",
    ]
  }
}

Alternatively, you can create this in the UI or via gcloud.

• You must also configure your cluster to send notifications to the topic when upgrade events are triggered. This is currently available for configuration via Terraform in the google-beta provider:

resource "google_container_cluster" "cluster" {
  provider = google-beta

  ...

  notification_config {
    pubsub {
      enabled = true
      topic   = "name-of-pubsub-topic"
    }
  }
}

Alternatively, you can enable this on a cluster via gcloud. More context available here.

• Finally, you'll need to deploy the Cloud Function:

resource "google_cloudfunctions_function" "gke_cluster_upgrade_notifications" {
  name        = "gke-cluster-upgrade-notifications"
  description = "Sends notifications to Slack for GKE cluster upgrade notifications."
  runtime     = "python38"

  available_memory_mb   = 128
  entry_point           = "notify_slack"
  ingress_settings      = "ALLOW_INTERNAL_ONLY"
  source_archive_bucket = "gcs-bucket-name"
  source_archive_object = "main.py.zip"
  timeout               = 30

  environment_variables = {
    SLACK_WEBHOOK_URL = "foo"
  }

  event_trigger {
    event_type = "google.pubsub.topic.publish"
    resource   = google_pubsub_topic.gke_cluster_upgrade_notifications.id
    failure_policy {
      retry = true
    }
  }

  labels = {
    ...
  }
}

Alternatively, you can create this in the UI or via gcloud. You can interpet the important bits from the example above.

Note: The Terraform examples are only provided as a starting point.