thothctl

Check Dependencies Command

Overview

The check deps command visualizes and analyzes infrastructure dependencies in your Terragrunt projects. It parses the DAG (Directed Acyclic Graph) from terragrunt dag graph, calculates component risk scores, and renders the topology in multiple formats.

Usage

# Default: Rich tree with risk percentages
thothctl check iac -type deps

# ASCII box topology (best for terminal sharing)
thothctl check iac -type deps --format boxart

# Interactive HTML in browser (vis.js graph)
thothctl check iac -type deps --format html

# Raw DOT output (pipe to graphviz or other tools)
thothctl check iac -type deps --format dot

Output Formats

Format	Description	Use Case
`tree`	Rich tree with color-coded risk	Default terminal view
`boxart`	ASCII box drawing topology	Copy/paste into docs, Slack, PRs
`html`	Interactive vis.js graph in browser	Presentations, exploration
`dot`	Raw GraphViz DOT	Pipe to `dot`, `neato`, custom tools

Tree (default)

Infrastructure Modules
└── stacks/observability/network/reachability-analyzer (31.0% risk)
    ├── stacks/foundation/network/security-groups (38.5% risk)
    │   └── stacks/foundation/network/vpc (46.5% risk)
    └── stacks/platform/data/rds (42.5% risk)

✅ Found 5 stacks, 12 modules, 10 dependencies

The summary counts:

Stacks: nodes in the dependency graph (directories with terragrunt.hcl)
Modules: total module blocks across all stack .tf files
Dependencies: edges in the DAG (from dependency blocks)

Boxart

┌───────────────┐  ┌──────────────────┐
│ vpc 47%       │  │ security-groups 39% │
└───────────────┘  └──────────────────┘
         │                    │
         ▼                    ▼
┌───────────────┐  ┌──────────────────┐
│ rds 43%       │  │ vpc-lattice 34%  │
└───────────────┘  └──────────────────┘

For best quality boxart, install graph-easy:

OS	Install Command
Linux (Debian/Ubuntu)	`sudo apt install libgraph-easy-perl`
macOS	`brew install graph-easy`
Windows	`choco install graphviz` then use `--format dot \\| dot -Tpng -o graph.png`

Note: Without graph-easy, ThothCTL uses a built-in Python fallback renderer.

HTML

Opens an interactive topology in your default browser with:

Hierarchical top-down layout
Color-coded nodes (green < 30% risk, orange 30-50%, red > 50%)
Hover for full stack path
Saved to Reports/dependency_topology.html

DOT

Outputs raw DOT graph for piping:

# Generate PNG image
thothctl check iac -type deps --format dot | dot -Tpng -o topology.png

# Generate SVG
thothctl check iac -type deps --format dot | dot -Tsvg -o topology.svg

# Open in xdot viewer
thothctl check iac -type deps --format dot | xdot -

Prerequisites

Tool	Required	Install
`terragrunt`	✅ Required	terragrunt.gruntwork.io
`graphviz`	Optional (for `--format dot` piping)	See below
`graph-easy`	Optional (for `--format boxart` enhanced output)	See below

Installing Graphviz

OS	Command
Linux (Debian/Ubuntu)	`sudo apt install graphviz`
macOS	`brew install graphviz`
Windows	`choco install graphviz`

Installing graph-easy

OS	Command
Linux (Debian/Ubuntu)	`sudo apt install libgraph-easy-perl`
macOS	`brew install graph-easy`
Windows (WSL)	`sudo apt install libgraph-easy-perl`

Windows native: graph-easy is a Perl tool. On native Windows, use WSL or the --format html alternative.

Features

Risk Assessment: Each component gets a risk percentage based on fan-in/fan-out degree and dependency depth
Terragrunt Details: Shows mock_outputs and config_path from dependency blocks
Multiple Renderers: Terminal, ASCII art, browser, and raw DOT
CI/CD Friendly: --format dot for pipeline image generation, --format boxart for PR comments

Examples

CI/CD Pipeline — Post topology to PR

# Generate boxart for PR comment
echo '```' > /tmp/deps.md
thothctl check iac -type deps --format boxart >> /tmp/deps.md
echo '```' >> /tmp/deps.md
gh pr comment --body-file /tmp/deps.md

Generate documentation artifact

thothctl check iac -type deps --format html
# → Opens browser + saves Reports/dependency_topology.html

check blast-radius — Assess change impact analysis
check tfplan — Analyze Terraform plans
inventory iac — Create dependency inventory
document iac — Generate documentation with graphs

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