elelement / creestop

Google Cloud Function allowing to start and stop many instances at a time.

Creestop

Google Cloud Function allowing to start and stop many instances at a time.

The code of this function allows to start and stop one or more existing GCE VMs at a time. The function is intended to consume instructions through Pub/Sub messages, the message format being the following:

variable "command" {
  type = object({
    command = string
    instances = list(object({
      name = string
      zone = string
    }))
  })
}

Thus, "command" can take (for now) only these two values:

• start: sends start order to instances.
• stop: envía la orden de stop order to instances.

Example

{
  "command": "start",
  "instances": [
    {
      "name": "ci-tableau-1", 
      "zone": "europe-west3-a"
    }, 
    {
      "name": "ci-tableau-2", 
      "zone": "europe-west3-b"
    },
    {
      "name": "ci-tableau-3", 
      "zone": "europe-west3-c"
    }
  ]
}

Deployment

You can easily deploy this function using either gcloud or Terraform or whatever you want. I provide an example using gcloud.

gcloud beta functions deploy <function-name> \
  --project=<project> \
  --region=<region> \
  --source=https://source.developers.google.com/projects/<project>/repos/<repo-name> \
  --runtime=nodejs10 \
  --trigger-topic=<topic-name> \
  --memory=128 \
  --service-account=<service-account-email> \
  --ingress-settings=<all, internal-only> \
  --timeout=<timeout in seconds, i.e. 120s> \
  --entry-point=<function handler>

Examples

Deploy with Terraform two Cloud Scheduler jobs to programmatically start and stop instances. The following instances will be used:

Instance name	Zone
ci-tableau-1	europe-west3-a
ci-tableau-2	europe-west3-b
ci-tableau-3	europe-west3-c

By using locals in Terraform, we simplify command construction.

locals {
  start_command = {
    command = "start",
    instances = local.instances
  }
  stop_command = {
    command = "stop",
    instances = local.instances
  }
  instances = [
    {
      name: "ci-tableau-1",
      zone: "europe-west3-a"
    },
    {
      name: "ci-tableau-2",
      zone: "europe-west3-b"
    },
    {
      name: "ci-tableau-3",
      zone: "europe-west3-c"
    }
  ]
}

Create a Cloud Scheduler job "start_job":

resource "google_cloud_scheduler_job" "start_job" {
  name        = "cron-start-1"
  description = "Start Tableau"
  schedule    = "0 9 * * mon-fri"
  region      = "europe-west1" # In my tests it only allowed me to enable AppEngine in Europe West 1.

  pubsub_target {
    topic_name = google_pubsub_topic.topic.id # The topic to publish the message.
    data       = base64encode(jsonencode(local.start_command)) # The CF "eats" JSON.
  }

  depends_on = [google_app_engine_application.default]
}

And another for "stop_job":

resource "google_cloud_scheduler_job" "stop_job" {
  name        = "cron-stop-1"
  description = "Stop Tableau"
  schedule    = "0 19 * * mon-fri"
  region      = "europe-west1"

  pubsub_target {
    topic_name = google_pubsub_topic.topic.id
    data       = base64encode(jsonencode(local.stop_command))
  }

  depends_on = [google_app_engine_application.default]
}

TODO

• Allow custom startup script (GCS location).
• Allow custom stop script (GCS location).