forest-fire [alt text](img/win95tree.png "fancy schmancy forest-fire logo")

This is a little command-line tool with an ill-advised name, to easily tear down CloudFormation stacks which have exports that other stacks depend on. In the AWS Console this is rather annoying, since you have to manually chase up dependencies.

This tool simply interrogates the aws-cli tool about the stack you're trying to delete, finds out its exports, and checks whether any currently-active stacks are importing them. The result is a dependency tree, which trivially tells us the correct order of deletion. If you're feeling credulous, you may also let forest-fire do the actual deletion for you with the --delete flag.

Installation

If you're not interested in hacking on this project, you can simply download and install it. You'll need the Cabal (not-quite-)package manager for that.

To get Cabal, do something like this:

brew cask install haskell-platform      # For Homebrew on macOS
sudo apt-get install haskell-platform   # For Ubuntu / Debian-like distros

Then install forest-fire:

cabal update                        # Update packages
cabal install forest-fire           # Install forest-fire for current user

You'll then need to add something like ~/Library/Haskell/bin to your $PATH; this is where Cabal installs executables.

Try the following command for enlightenment.

forest-fire --help

Prerequisites for hacking

You'll need the following installed and available to be able to hack on or contribute to this software:

Haskell Stack

You'll want to install Stack using your local package manager (yes, it's available on Homebrew as haskell-stack), or if you're adventurous, using their curl | bash method...

You'll need to add ~/.local/bin to your $PATH.

AWS CLI interface

I'm guessing that this is a thing you'll already have.

Usage

If you simply run the tool without arguments, it'll print usage information. Here's the down-low, however.

Find out what depends on a stack

Note that by default forest-fire performs a dry run (read-only). The order in which you'd have to perform deletions will be printed, but nothing will be executed.

One or more stack names can be provided as command-line arguments.

forest-fire "kubernetes-dynamic-91acf0ef-lifecycle"

Perform the deletions if you're satisfied with the results

forest-fire "kubernetes-dynamic-91acf0ef-lifecycle" --delete

Do you Docker?

Some people don't believe in native executables. For them, i present the Dockerised version:

docker container run --rm \
    -e AWS_SECRET_ACCESS_KEY \
    -e AWS_ACCESS_KEY_ID \
    -e AWS_DEFAULT_REGION \
    paulrb/forest-fire:master yourstack

It is hosted on Docker Hub: https://hub.docker.com/r/paulrb/forest-fire and built with Travis CI: https://travis-ci.org/toothbrush/forest-fire from this repository.

Credits

Thanks Redbubble, i totally should've been doing other things instead of shaving this yak.