Stacklight

A suite of developer tools for AWS CloudFormation workflows. Stacklight makes deploying, auditing, and understanding infrastructure-as-code faster and more readable.

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Tools

Tool	What it does	Language
cse	Translates CloudFormation change sets into plain English before you deploy	Python
drift	Detects stack drift and generates a structured remediation report	Zsh
cfcat	Concatenates CloudFormation templates into an LLM-ready summary + interactive diagram	Python
chromaform	VSCode extension that adds syntax highlighting to CloudFormation, Kubernetes, and GitHub Actions YAML	JavaScript

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Quick Install

One command — installs all four tools:

git clone https://github.com/YOUR_USERNAME/stacklight.git
cd stacklight
./install.sh
source ~/.zshrc

Then reload your VSCode window (Cmd+Shift+P → Reload Window) to activate chromaform.

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Prerequisites

Dependency	Required by	Install
Python 3	cse, cfcat	python.org
AWS CLI	cse, drift	brew install awscli
jq	drift	brew install jq
VSCode	chromaform	code.visualstudio.com
boto3	cse	pip3 install boto3
PyYAML	cfcat (optional)	pip3 install pyyaml
anthropic	cse (optional)	pip3 install anthropic

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Tools at a Glance

cse — Change Set Explainer

CloudFormation change sets are hard to read. cse creates a change set and rewrites the output in plain English — with risk levels, downtime estimates, data-loss callouts, and a "why is this being replaced?" breakdown. By default it gates on any replacement or deletion and exits non-zero, blocking accidental destructive deploys in CI.

cse --stack-name my-stack --template-file template.yaml           # show plan, gate on replacements/deletions
cse --stack-name my-stack --template-file template.yaml --warn-only --execute --no-interactive   # warn, don't block
cse --stack-name my-stack --template-file template.yaml --auto-approve --execute --no-interactive # deploy regardless

Set ANTHROPIC_API_KEY to enable AI-powered explanations via Claude.

→ Full docs

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drift — Drift Detector

drift runs CloudFormation drift detection and turns the raw API output into a clean terminal summary plus an optional markdown report with a copy-paste LLM context block for remediation help.

drift my-stack-name
drift my-stack-name --out
drift my-stack-name --region us-west-2 --profile staging

→ Full docs

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cfcat — CloudFormation Catalog

cfcat reads one or more CloudFormation templates (or entire directories) and produces a structured, LLM-friendly summary of your infrastructure — including cross-stack dependencies, resource wiring, and deployment order. Can also generate an interactive HTML diagram.

cfcat template.yaml
cfcat ./infra/ -o summary.txt
cfcat ./infra/ --html
cfcat ./infra/ --docs

→ Full docs

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chromaform — YAML Syntax Highlighter

A VSCode extension that colors YAML keys by indentation depth and adds semantic highlighting for CloudFormation resource types, intrinsic functions, Kubernetes kinds, and GitHub Actions expressions. Makes dense YAML files significantly easier to scan.

No configuration needed — it activates automatically on any .yaml file.

→ Full docs

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Configuration

AI mode for cse

Set your Anthropic API key to enable Claude-powered explanations:

export ANTHROPIC_API_KEY=sk-ant-...

Add it to ~/.zshrc to make it permanent. Without it, cse falls back to its built-in knowledge base (still very useful).

AWS credentials

All tools that talk to AWS (cse, drift) use standard boto3/AWS CLI credential resolution — environment variables, ~/.aws/credentials, or instance profiles. Pass --profile and --region to override per-command.

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What "stacklight" means

A stack light (or andon light) is the industrial signal tower on a factory floor that tells workers at a glance whether a machine is running, warning, or faulted. These tools are the signal lights for your CloudFormation stacks — they surface what's happening, what's changed, and what needs attention, without digging through the AWS console.