GumGum AMI Bakery

TL;DR: Packer + checksums = 👍

corey@gumgum.com

About GumGum

• Computer Vision company located in Santa Monica
• Advertising space
  • Context-aware in-image ads
  • Brand-safety technology
• New verticals:
  • Sports (working with teams in the NBA and NHL)
  • Dental

Project Goals

• Use Hashicorp Packer
  • Dependable

  • -debug

• AMIs defined 100% in code
• Idempotent builds
  • AMIs are only re-built when their definition changes
• Solution must be CI-friendly

Problem

• Packer builds are not idempotent
  • Re-building the same code twice = 2 AMIs
• Makes integrating Packer into your CI challenging

Solution

• Introducing the GumGum AMI Bakery Docker image!
• You tell the AMI Bakery where your AMI config code lives
• The AMI Bakery will then re-build your AMI only if your AMI config code changes

GumGum AMI Bakery

File Checksums

• Digital signatures for files
  • Our AMI Bakery uses SHA1 checksums
• Returns a 40 character hexidecimal value for files or strings of any size
• If any part of a file changes, so will its SHA1 checksum

Our AMI Bakery Algorithm

Before The AMI Bakery 😥

After 😎

• GumGum AMI Bakery stage inserted
  • If the AMI DNE, it is built
  • If it exists, the AMI's ID is returned
• Terraform passed the AMI ID via CLI parameter

New stage

Updated stage

Demo

Advantages

• AMI updates are simple:
  • Update the AMI config code
  • That's it.
• No external state
• AMI config checksums remain the same between branch changes = faster builds

Disadvantages

• A little invasive
  • Need to update existing Terraform code to look up AMIs dynamically
  • But maybe that's a good thing?

GumGum AMI Bakery Code

• https://github.com/mechtron/ami-bakery

• Includes an example sample-app

Example Pipeline Integration