How to Structure a Large Go Application

Structure a large Go application by organizing code into a cmd directory for entry points and a pkg or internal directory for shared libraries, following the standard Go project layout. Place your main application logic in cmd/myapp/main.go and reusable packages in pkg/ or internal/ to enforce visibility rules.

mkdir -p cmd/myapp pkg/utils internal/config
touch cmd/myapp/main.go pkg/utils/helper.go internal/config/settings.go

1. Create the cmd directory for application entry points and add your main file. mkdir -p cmd/myapp && touch cmd/myapp/main.go
2. Create the pkg directory for public libraries that other projects can import. mkdir -p pkg/utils && touch pkg/utils/helper.go
3. Create the internal directory for private libraries that only your application can import. mkdir -p internal/config && touch internal/config/settings.go
4. Initialize the module to manage dependencies and enforce the directory structure. go mod init myapp
5. Build the application from the root to verify the structure compiles correctly. go build ./cmd/myapp

Think of your Go project like a house: the cmd folder is the front door where the program starts, pkg is the shared toolbox anyone can use, and internal is the private workshop only you can access. This separation keeps your code organized, prevents accidental changes to private logic, and makes it easy for others to understand how your application works.