Go

Railpack builds and deploys Go applications with static binary compilation.

Detection

Your project will be detected as a Go application if any of these conditions are met:

• A go.mod file exists in the root directory
• A go.work file exists in the root directory (Go workspaces)
• A main.go file exists in the root directory

Versions

The Go version is determined in the following order:

• Read from the go.mod file
• Set via the RAILPACK_GO_VERSION environment variable
• Defaults to 1.23

Configuration

Railpack builds your Go application as a static binary by default. The build process:

• Installs Go dependencies
• Builds your application with optimized flags (-ldflags="-w -s")
• Names the output binary out

Railpack determines the main package to build in the following order:

1. The module specified by the RAILPACK_GO_WORKSPACE_MODULE environment variable (for workspaces)
2. The package specified by the RAILPACK_GO_BIN environment variable
3. The root directory if it contains Go files
4. The first subdirectory in the cmd/ directory
5. For workspaces: the first module containing a main.go file
6. The main.go file in the root directory

Config Variables

Variable	Description	Example
RAILPACK_GO_VERSION	Override the Go version	1.22
RAILPACK_GO_BIN	Specify which command in cmd/ to build	server
RAILPACK_GO_WORKSPACE_MODULE	Specify which workspace module to build	api
CGO_ENABLED	Enable CGO for non-static binary compilation	1

Go Workspaces

Railpack supports Go workspaces (introduced in Go 1.18) for multi-module projects:

• Detects projects with a go.work file at the root
• Automatically discovers and copies all module dependencies
• Builds the first module with a main.go file by default
• Use RAILPACK_GO_WORKSPACE_MODULE to specify which module to build

Example workspace structure:

├── go.work
├── api/
│   ├── go.mod
│   └── main.go
└── shared/
    ├── go.mod
    └── lib.go

To build a specific module:

RAILPACK_GO_WORKSPACE_MODULE=api

CGO Support

By default, Railpack builds static binaries with CGO_ENABLED=0. If you need CGO support:

• Set the CGO_ENABLED environment variable to 1
• Railpack will include the necessary build dependencies (gcc, g++, libc6-dev)
• The runtime image will include libc6 for dynamic linking