Packer Cheat Sheet

Quick reference for HashiCorp Packer templates, builders, provisioners, and CLI commands used to build immutable machine images.

2 PagesIntermediateFeb 5, 2026

Basic Commands

Core Packer CLI workflow.

bash

packer init .                 # Download required pluginspacker fmt .                  # Format HCL filespacker validate .             # Validate template syntaxpacker build .                # Build image(s) defined in templatepacker build -var 'region=us-east-1' .   # Pass a variablepacker build -only='amazon-ebs.ubuntu' . # Build a single named source

HCL2 Template

Minimal image build definition using the amazon-ebs builder.

hcl

packer {  required_plugins {    amazon = {      version = ">= 1.2.0"      source  = "github.com/hashicorp/amazon"    }  }}source "amazon-ebs" "ubuntu" {  ami_name      = "my-app-{{timestamp}}"  instance_type = "t3.micro"  region        = "us-east-1"  source_ami_filter {    filters = {      name = "ubuntu/images/*ubuntu-jammy-22.04-amd64-server-*"    }    owners      = ["099720109477"]    most_recent = true  }  ssh_username = "ubuntu"}build {  sources = ["source.amazon-ebs.ubuntu"]  provisioner "shell" {    inline = ["sudo apt-get update", "sudo apt-get install -y nginx"]  }}

Provisioners

Mechanisms Packer uses to configure the image during build.

shell- Runs inline commands or a local script on the instance being built
file- Uploads a local file or directory to the build instance
ansible- Runs an Ansible playbook against the temporary build instance
powershell- Runs PowerShell commands, typically for Windows image builds
post-processor "vagrant"- Packages the finished build output into a Vagrant box
post-processor "manifest"- Writes build artifact metadata (IDs, timestamps) to a JSON file

Common Builders (Sources)

Plugins that define which platform an image is built for.

amazon-ebs- Builds an AMI backed by an EBS snapshot on AWS
googlecompute- Builds a custom image on Google Compute Engine
azure-arm- Builds a managed image or VM image on Azure
docker- Builds and commits a Docker image using a running container
qemu- Builds a QEMU/KVM disk image, useful for local or on-prem virtualization
virtualbox-iso- Builds a VirtualBox VM image starting from an ISO installer

Pro Tip

Use `packer build -only` and multiple named `source` blocks to build several platform images (AWS, Azure, Docker) from one shared template and one set of provisioners, keeping configuration DRY across clouds.

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