Google GKE startup script not workin for GKE Node

Question

I am adding a startup script to my GKE nodes using terraform

provider "google" {
  project = var.project
  region  = var.region
  zone    = var.zone
  credentials = "google-key.json"
}


terraform {
  backend "gcs" {
    bucket = "tf-state-bucket-devenv"
    prefix = "terraform"
    credentials = "google-key.json"
   }
}

resource "google_container_cluster" "primary" {
  name     = var.kube-clustername
  location = var.zone
  remove_default_node_pool = true
  initial_node_count       = 1

  master_auth {
    username = ""
    password = ""

    client_certificate_config {
      issue_client_certificate = false
    }
  }
}

resource "google_container_node_pool" "primary_preemptible_nodes" {
  name       = var.kube-poolname
  location   = var.zone
  cluster    = google_container_cluster.primary.name
  node_count = var.kube-nodecount

  node_config {
    preemptible  = var.kube-preemptible
    machine_type = "n1-standard-1"
    disk_size_gb = 10
    disk_type = "pd-standard"


    metadata = {
      disable-legacy-endpoints = "true",
      startup_script = "cd /mnt/stateful_partition/home && echo hi > test.txt"
    }

    oauth_scopes = [
      "https://www.googleapis.com/auth/logging.write",
      "https://www.googleapis.com/auth/monitoring",
    ]
  }
}

When i go into the GCP interface, select the node and view the metadata I can see the key/value is there

metadata_startup_script 
#!/bin/bash sudo su && cd /mnt/stateful_partition/home && echo hi > test.txt

However when running the below command on the node -

sudo google_metadata_script_runner --script-type startup - -debug

I got the below -

startup-script: INFO Starting startup scripts.
startup-script: INFO No startup scripts found in metadata.
startup-script: INFO Finished running startup scripts.

Does anyone know why this script is not working/showing up? - Is it because its a GKE node and google dont let you edit these, I cant actually find anything on their documentation where they specifically say that.

user_4215791 · Answer

You cannot specify startup scripts to run on GKE nodes. The node has a built-in startup sequence to initialize the node and join it to the cluster and to ensure that this works properly (e.g. to ensure that when you ask for 100 nodes you get 100 functional nodes) you cannot add additional logic to the startup sequence.

As an alternative, you can create a DaemonSet that runs on all of your nodes to perform node-level initialization. One advantage of this is that you can tweak your DaemonSet and re-apply it to existing nodes (without having to recreate them) if you want to change how they are configured.

user_11372593 · Answer

Replace this metadata key name metadata_startup_script by this one startup_script.

In addition, your startup script runs as root user. you don't need to perform a sudo su

Google GKE startup script not workin for GKE Node

2 Answers