How to use cloud-init with Terraform?



I am working with Digital Ocean and Terraform and I already can automate the domain, subdomain, network preferences and the host but there is a section called User data that looks like this:

User data

The description of that field says Allows the use of Cloud-init to configure your droplet. Looking around I found the documentation.

My question is, how to take advantage of this while using Terraform?


Posted 2017-02-28T16:59:16.180

Reputation: 1 123



Cloud-init files are essentially bootstrap codes, that run before each startup, and can - among others - modify files, set up services, create users, etc.

Not all types of droplets support all functionalities of cloud-init, for example CoreOS uses it's own implementation, with a very limited subset of valid values.

To use this in terraform, simply provide the cloud-init file during droplet creation:

resource "digitalocean_droplet" "web" {
  image              = "coreos-stable"
  name               = "web"
  region             = "lon1"
  size               = "2gb"
  private_networking = true
  ssh_keys           = ["${}"]
  user_data          = "${file("web.conf")}"


    - name: "etcd2.service"
      command: "start"
    - name: "fleet.service"
      command: "start"

This will for example create a droplet, where CoreOS will run etcd2 and fleet during startup

You can find some more examples in this repository, where I show how one can use these configuration options to set up some simple docker based services on CoreOS


Posted 2017-02-28T16:59:16.180

Reputation: 1 357


When you create an Auto Scaling group with Terraform, you can specify the user_data to be used by instances created by this ASG. Documented here -

You can also create a single EC2 instance, and provide user_data to be used -

The AWS EC2 documentation explains how user_data is passed to the cloud-init service which is running on most Linux distributions available as AMIs on AWS -


Posted 2017-02-28T16:59:16.180

Reputation: 7 247