Go CLI Application Architecture

Organize around dependency direction and testable behavior, not a copied folder template. Keep CLI framework code as an adapter around application services.

Core Workflow

1. Identify commands, domain actions, external effects, and shared policies.
2. Separate parsing/rendering from application orchestration and adapters.
3. Define interfaces at the consumer that needs substitution.
4. Construct dependencies once in a composition root and pass them explicitly.
5. Keep configuration immutable after validation; give mutable state a dedicated store.
6. Record ownership and cleanup for every acquired resource and background task.
7. Test inward from pure logic to adapters and one assembled executable path.

Read Next

Task	Load
Design or refactor boundaries	guidelines.md, workflows/design-application-boundaries.md
Review ownership and cleanup	workflows/review-resource-lifecycle.md
Decide package and interface placement	references/application-architecture/rules.md
Review patterns and examples	references/application-architecture/examples.md
Understand dependency direction	references/application-architecture/knowledge.md

Guardrails

• Do not put domain behavior in Cobra Run functions.
• Avoid a central interfaces package and broad catch-all service abstractions.
• Do not use package globals or init for dependency construction.
• Keep fallible I/O and order-dependent startup out of init; use explicit composition.
• Keep runtime configuration distinct from mutable application storage.
• Add layers only when they create a real seam, invariant, or dependency boundary.

Source Notes

Guidance is transformed and paraphrased from Marian Montagnino, Building Modern CLI Applications in Go (Packt, 2023), especially Chapters 2-3, with original adaptations aligned to current Go conventions.

Concrete-first interfaces, dependency ownership, and adapter lifecycle guidance also incorporates transformed material from Inanc Gumus, Go by Example: Programmer's Guide to Idiomatic and Testable Programs (Manning, 2025), Chapters 5 and 8-10.

Initialization and lifecycle guidance also incorporates transformed material from Teiva Harsanyi, 100 Go Mistakes and How to Avoid Them (Manning, 2022), Chapters 2, 6, 7, and 10.