Packer

ELI5 — The Vibe Check

Packer builds machine images (AMIs, Docker images, VM images) from code. Define what you want installed, Packer builds the golden image. Every server starts identical. No more 'this server has a slightly different Python version' nightmares. It's a factory for server blueprints.

Real Talk

HashiCorp Packer is an open-source tool for creating identical machine images for multiple platforms from a single source configuration. It supports builders for AWS, Azure, GCP, Docker, VMware, and more. Uses provisioners (shell, Ansible, Chef) to install software on temporary instances, then captures the result as an image.

Show Me The Code

packer {
  required_plugins {
    amazon = {
      source  = "github.com/hashicorp/amazon"
    }
  }
}
source "amazon-ebs" "ubuntu" {
  ami_name      = "my-app-{{timestamp}}"
  instance_type = "t3.micro"
  source_ami    = "ami-0abcdef1234567890"
}
build {
  sources = ["source.amazon-ebs.ubuntu"]
  provisioner "shell" {
    script = "setup.sh"
  }
}

When You'll Hear This

"Packer builds our golden AMI with all dependencies pre-installed." / "We run Packer in CI — every merge to main produces a new machine image."