NewPkg initializes a new Pkg.

Alpine is the Alpine variant.

Scratch is the Scratch variant.

Dependency defined the dependency for a package.

Finalize the package.

Options are the options for the build.

Pkg defines the package to build.

Source define a package source options.

Step defines a step in the build process.

Install configures the install packages.

Instruction defines the instruction for a package.

Shell is the shell to use for the package.

Variant defines the variant of the package.