[Packer](https://www.packer.io/) is a tool to create automated machine images in both local virtual machine / container environments, as well as a variety of cloud platforms. My current cloud platform of choice is [Digital Ocean](https://www.digitalocean.com/), so this post will explain how to set up Packer with it. Though you can likely find your platform of choice on their [docs](https://www.packer.io/docs/builders/) page
In this post I am going to use the beta configuration language of HCL2. This requires a Packer version of at least 1.5.
## Variables
First let us set up a variables file which we will later reference. This makes it easy to keep your main Packer configuration files in Git, while not committing your API key.
Create a file called `variables.auto.pkrvars.hcl`. Here is some example variables and values that I put in mine.
```
base_system_image = "ubuntu-20-04-x64"
region = "nyc3"
size = "512mb"
do_token = "DOTOKENHERE" # Secret
```
Then we need to create `variables.pkr.hcl` that define the types of each of these variables
```
variable "do_token" {
type = string
}
variable "base_system_image" {
type = string
}
variable "region" {
type = string
}
variable "size" {
type = string
}
```
## Provisioning
Once the system is up and running we can use a [variety of tools](https://www.packer.io/docs/provisioners/) that setup the image.
- Ansible
- Chef
- Powershell
- etc.
I'll use a simple bash script as an example
```bash
#!/bin/bash
apt update
apt upgrade -y
```
## Piecing it together
Finally let us create a `do.pkr.hcl` file that contains the following information
```
source "digitalocean" "web" {
api_token = var.do_token
image = var.base_system_image
region = var.region
size = var.size
ssh_username = "root"
snapshot_name = "packer-example"
}
build {
sources = [
"source.digitalocean.web",
]
provisioner "shell" {
scripts = [ "setup.sh" ]
}
}
```
Assuming all the files we've just created are in the same directory, Packer will automatically recognize where the value for `var.do_token` lives. We can then run packer to build the image
```bash
packer build .
```
This sets up a snapshot called `packer-example` which we can later spin up and use! Keep in mind that it does a small amount of money to store images on DigitalOcean.
