gomodwhy

README

gomodwhy

A tool to analyze why a specific package is included in your Go project's dependency graph, just like go mod why.

• go mod why only shows the first import path, while this tool will find all possible import paths.
• go mod graph always includes test dependencies, while this tool exclude test dependencies by default and provide an option to include them.

What does it do?

gomodwhy helps you understand the dependency chain that leads to a particular package being included in your Go project. It:

• Builds a comprehensive dependency graph of your project
• Finds all possible import paths from your project to the target package
• Displays the dependency chains in a go mod why way
• Supports depth limiting for complex dependency trees
• Allows including test dependencies in the analysis
• Works with any Go module

Installation

go install github.com/ycydsxy/gomodwhy@latest

Usage

gomodwhy [options] <target-pkg>

Options

• -p, --pattern - Go list package matching pattern (default: .)
• -d, --depth - Dependency path depth limit, 0 for unlimited (default: 0)
• -t, --include-test - Include test dependencies
• -v, --verbose - Print verbose information

Examples

Find why a package is imported in the current directory

gomodwhy fmt
# fmt
code.byted.org/suxiangyu/gomodwhy
fmt

code.byted.org/suxiangyu/gomodwhy
encoding/json
fmt

code.byted.org/suxiangyu/gomodwhy
github.com/jessevdk/go-flags
fmt

code.byted.org/suxiangyu/gomodwhy
github.com/jessevdk/go-flags
golang.org/x/sys/unix
fmt

Limit dependency path depth

gomodwhy -d 1 fmt
# fmt
code.byted.org/suxiangyu/gomodwhy
fmt

github.com/jessevdk/go-flags
fmt

encoding/json
fmt

golang.org/x/sys/unix
fmt

Use with a specific package pattern

gomodwhy -p github.com/jessevdk/go-flags fmt
# fmt
github.com/jessevdk/go-flags
fmt

github.com/jessevdk/go-flags
golang.org/x/sys/unix
fmt

Verbose output

gomodwhy -v fmt
Executing go list command to get dependency information...
Successfully got dependency information for 72 packages
Building dependency graph...
Dependency graph built successfully
Analyzing dependency paths...
Analysis completed, found 4 dependency paths

# fmt
code.byted.org/suxiangyu/gomodwhy
fmt

code.byted.org/suxiangyu/gomodwhy
github.com/jessevdk/go-flags
fmt

code.byted.org/suxiangyu/gomodwhy
encoding/json
fmt

code.byted.org/suxiangyu/gomodwhy
github.com/jessevdk/go-flags
golang.org/x/sys/unix
fmt

Include test dependencies

gomodwhy -t github.com/stretchr/testify
# github.com/stretchr/testify
code.byted.org/suxiangyu/gomodwhy
github.com/stretchr/testify

How it works

1. Dependency Collection: Uses go list -deps -json (with -test flag if test dependencies are included) to gather dependency information
2. Graph Construction: Builds both forward and reverse dependency graphs, including test imports if requested
3. Path Analysis: Uses BFS (Breadth-First Search) to find all paths from your project to the target package
4. Path Processing: Handles depth limits and removes duplicate paths
5. Output: Displays the dependency chains in a clear format

License

This project is licensed under the Apache License 2.0 - see the LICENSE file for details.

Contributing

Contributions are welcome! Please feel free to submit a Pull Request.