[SOLVED] Bypassing 16KB EC2 user_data limitation

Issue

Is there a way to bypass the 16KB EC2 user_data limitation without any custom AMI? I have tried below examples in Terraform without any success. instance-user-data.ps1.tmpl is a powershell script of about 20KB.

Below script using base64encode complains about going over 16KB

resource "aws_instance" "instance" {
  ...

  user_data_base64 = "${base64encode(templatefile("${path.module}/instance-user-data.ps1.tmpl", {
    admin_username                = local.admin_username
    admin_password                = random_password.admin_password.result
  }))}"
}

Tried Gzip with Base64 encode as well, but script does not set any user data at all.

resource "aws_instance" "instance" {
  ...

  user_data_base64 = "${base64gzip(templatefile("${path.module}/instance-user-data.ps1.tmpl", {
    admin_username                = local.admin_username
    admin_password                = random_password.admin_password.result
  }))}"
}

Solution

The way I would get around this is to push your scripts/files to S3, which can be done with the Terraform aws_s3_object resource, and simply have your user_data script download the real startup script from S3 and run it.

Answered By - Mark B

Answer Checked By - Willingham (WPSolving Volunteer)