Build specs

Build specs declare everything about a package, the fundamental unit of software in Minimal.

This declaration includes:

• The packages that are needed to build the software, including runtime dependencies (i.e. need to be present wherever this software runs)
• The source code, and configuration to build the software
• Extensive metadata capture information such as software version, the provenance of source code, directories used at runtime for state, and a number of other data points.

Build specs are defined in a Nickel file located at packages/<package name>/build.ncl, either in your codebase or any layer in your software supply chain. The packages/ directory in a layer is always adjacent to the minimal.toml file at its base. The directory can be omitted if the layer does not define any packages.

Example

Here is a simplified build spec for jq, based on the Minimal Public Package Registry:

let { build_spec, .. } = import "minimal.ncl" in
build_spec {
  name = "jq",

  build_deps = [
    { src = { url = "https://github.com/jqlang/jq/releases/download/jq-1.8.1/jq-1.8.1.tar.gz", sha256 = "..." } },
    { pkg = "make" },
    { pkg = "gcc" },
    { pkg = "glibc" },
  ],

  runtime_deps = [
    { pkg = "glibc" },
  ],

  cmd = ["./build.sh"],

  outputs = {
    bin = { glob = "usr/bin/*" },
    lib = { glob = "usr/lib/*" },
    man = { glob = "usr/share/man/**" },
  },

  tests = {
    smoketest = { cmd = ["jq", "--version"] },
    basic = { cmd = [
      "/bin/bash", "-c",
      "echo '{\"name\": \"minimal\"}' | jq -r '.name' | grep -q minimal"
    ]},
  },

  attrs = {
    upstream_version = "1.8.1",
  },
}

Each package also has a build.sh script adjacent to build.ncl that performs the actual compilation.

More examples are maintained in the Minimal Public Package Registry.

Schema

The canonical typing of a Build-spec is defined using Nickel in Minimal's embedded standard library, in crates/stdlib/minimal-ncl/minimal.ncl (the BuildSpec contract).

Field name	Type	Usage
name	String	Declares the name of the package. May only contain alphanumeric characters, dashes, and underscores. Must match the name of the containing directory.
build_deps	Array<BuildDep>	A list of dependencies that are needed at build time. This may be: - Other packages - Subsets of other packages - Source objects - Local objects
runtime_deps	Array<RuntimeDep>	A list of dependencies that are needed both at build time, and wherever the package is needed. These may be: - Other packages - Subsets of other packages
cmd, cmds	Array<String> or Array<Array<String>>	The command that is invoked to build the package. This is either an array of arguments, or an array of commands, each of which is an array of arguments.
build_args	Map<String, String>	A list of arguments to be passed to the build command. These are made available to the build commands as environment variables. eg: build_args.abc = "def" would be available as the environment variable MINIMAL_ARG_ABC with the value def.
outputs	Map<String, Output>	The named set of output files that are captured from a build. If no files match a named output, it's a build error.
attrs	Attrs	The typed set of metadata attached to a given package.
needs	Needs	Any abstract needs declared on a given package.
tests	Map<String, Test>	A list of tests that are run by mip check.
target	String	The target string this package supports. Defaults to the current target.
prebuilt	Bool	Indicates that a package is not built, but just the unpacked files from the first Source object in build_deps.