Switch to the new "component" vs "composite" buildpack terminology

Upstream has now officially defined names for what we had previously
been calling meta-buildpacks vs single buildpacks:
https://github.com/buildpacks/spec/blob/main/buildpack.md#cnb-terminology

All types, docs and internal functions have been renamed to match.

Fixes #639.
GUS-W-14161652.

CHANGELOG.md

@@ -13,13 +13,15 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 - `libcnb-data`:
   - `ExecDProgramOutputKey`, `ProcessType`, `LayerName`, `BuildpackId` and `StackId` now implement `Ord` and `PartialOrd`. ([#658](https://github.com/heroku/libcnb.rs/pull/658))
-  - Add `generic::GenericMetadata` as a generic metadata type. Also makes it the default for `BuildpackDescriptor`, `SingleBuildpackDescriptor`, `MetaBuildpackDescriptor` and `LayerContentMetadata`. ([#664](https://github.com/heroku/libcnb.rs/pull/664))
+  - Added `generic::GenericMetadata` as a generic metadata type. Also makes it the default for `BuildpackDescriptor`, `SingleBuildpackDescriptor`, `MetaBuildpackDescriptor` and `LayerContentMetadata`. ([#664](https://github.com/heroku/libcnb.rs/pull/664))
 - `libcnb-test`:
   - Added the `BuildpackReference::WorkspaceBuildpack` enum variant. This allows for the testing of any libcnb.rs or composite buildpack in the Cargo workspace, instead of only the buildpack of the current crate. **Note: The testing of composite buildpacks requires `pack` CLI version `>=0.30`.** ([#666](https://github.com/heroku/libcnb.rs/pull/666))
 
 ### Changed
 
 - Renamed `libcnb-data`'s `Buildpackage` to `PackageDescriptor`. This required changes in many other names across multiple libcnb.rs crates for consistency. See the PR diff for details, but renames should be straightforward and unsurprising. ([#656](https://github.com/heroku/libcnb.rs/pull/656))
+- `libcnb-data`:
+  - Renamed multiple types to match the new composite vs component buildpack [upstream terminology](https://github.com/buildpacks/spec/blob/main/buildpack.md#cnb-terminology). Renamed `SingleBuildpackDescriptor` to `ComponentBuildpackDescriptor`, `MetaBuildpackDescriptor` to `CompositeBuildpackDescriptor` and `BuildpackDescriptor::{Single,Meta}` to `BuildpackDescriptor::{Component,Composite}`. ([#682](https://github.com/heroku/libcnb.rs/pull/682))
 - `libcnb-cargo`:
   - No longer outputs paths for non-libcnb.rs and non-meta buildpacks. ([#657](https://github.com/heroku/libcnb.rs/pull/657))
   - Build output for humans changed slightly, output intended for machines/scripting didn't change. ([#657](https://github.com/heroku/libcnb.rs/pull/657))

libcnb-cargo/tests/fixtures/multiple_buildpacks/meta-buildpacks/meta-one/buildpack.toml → libcnb-cargo/tests/fixtures/multiple_buildpacks/composite-buildpacks/composite-one/buildpack.toml

@@ -1,8 +1,8 @@
 api = "0.8"
 
 [buildpack]
-id = "multiple-buildpacks/meta-one"
-name = "Meta-buildpack Test"
+id = "multiple-buildpacks/composite-one"
+name = "Composite Buildpack Test"
 version = "0.0.0"
 homepage = "https://example.com"
 description = "Official test example"

libcnb-cargo/tests/integration_test.rs

@@ -42,12 +42,17 @@ fn package_buildpack_in_single_buildpack_project() {
 
 #[test]
 #[ignore = "integration test"]
-fn package_single_meta_buildpack_in_monorepo_buildpack_project() {
+fn package_single_composite_buildpack_in_monorepo_buildpack_project() {
     let fixture_dir = copy_fixture_to_temp_dir("multiple_buildpacks").unwrap();
 
     let output = Command::new(CARGO_LIBCNB_BINARY_UNDER_TEST)
         .args(["libcnb", "package", "--release"])
-        .current_dir(fixture_dir.path().join("meta-buildpacks").join("meta-one"))
+        .current_dir(
+            fixture_dir
+                .path()
+                .join("composite-buildpacks")
+                .join("composite-one"),
+        )
         .output()
         .unwrap();
 
@@ -61,14 +66,14 @@ fn package_single_meta_buildpack_in_monorepo_buildpack_project() {
         String::from_utf8_lossy(&output.stdout),
         format!(
             "{}\n",
-            packaged_buildpack_dir_resolver(&buildpack_id!("multiple-buildpacks/meta-one"))
+            packaged_buildpack_dir_resolver(&buildpack_id!("multiple-buildpacks/composite-one"))
                 .to_string_lossy()
         )
     );
 
-    validate_packaged_meta_buildpack(
-        &packaged_buildpack_dir_resolver(&buildpack_id!("multiple-buildpacks/meta-one")),
-        &buildpack_id!("multiple-buildpacks/meta-one"),
+    validate_packaged_composite_buildpack(
+        &packaged_buildpack_dir_resolver(&buildpack_id!("multiple-buildpacks/composite-one")),
+        &buildpack_id!("multiple-buildpacks/composite-one"),
         &[
             PackageDescriptorDependency::try_from(packaged_buildpack_dir_resolver(&buildpack_id!(
                 "multiple-buildpacks/one"
@@ -148,7 +153,9 @@ fn package_all_buildpacks_in_monorepo_buildpack_project() {
         format!(
             "{}\n",
             [
-                packaged_buildpack_dir_resolver(&buildpack_id!("multiple-buildpacks/meta-one")),
+                packaged_buildpack_dir_resolver(&buildpack_id!(
+                    "multiple-buildpacks/composite-one"
+                )),
                 packaged_buildpack_dir_resolver(&buildpack_id!("multiple-buildpacks/one")),
                 packaged_buildpack_dir_resolver(&buildpack_id!("multiple-buildpacks/two")),
             ]
@@ -157,9 +164,9 @@ fn package_all_buildpacks_in_monorepo_buildpack_project() {
         )
     );
 
-    validate_packaged_meta_buildpack(
-        &packaged_buildpack_dir_resolver(&buildpack_id!("multiple-buildpacks/meta-one")),
-        &buildpack_id!("multiple-buildpacks/meta-one"),
+    validate_packaged_composite_buildpack(
+        &packaged_buildpack_dir_resolver(&buildpack_id!("multiple-buildpacks/composite-one")),
+        &buildpack_id!("multiple-buildpacks/composite-one"),
         &[
             PackageDescriptorDependency::try_from(packaged_buildpack_dir_resolver(&buildpack_id!(
                 "multiple-buildpacks/one"
@@ -185,7 +192,7 @@ fn package_all_buildpacks_in_monorepo_buildpack_project() {
 
 #[test]
 #[ignore = "integration test"]
-fn package_non_libcnb_buildpack_in_meta_buildpack_project() {
+fn package_non_libcnb_buildpack_in_composite_buildpack_project() {
     let fixture_dir = copy_fixture_to_temp_dir("multiple_buildpacks").unwrap();
 
     let output = Command::new(CARGO_LIBCNB_BINARY_UNDER_TEST)
@@ -227,7 +234,7 @@ fn package_command_respects_ignore_files() {
     // The `ignore` crate supports `.ignore` files. So this first `cargo libcnb package` execution
     // just sanity checks that our ignore rules will be respected.
     let ignore_file = fixture_dir.path().join(".ignore");
-    fs::write(&ignore_file, "meta-buildpacks\nbuildpacks\n").unwrap();
+    fs::write(&ignore_file, "composite-buildpacks\nbuildpacks\n").unwrap();
 
     let output = Command::new(CARGO_LIBCNB_BINARY_UNDER_TEST)
         .args(["libcnb", "package", "--release"])
@@ -251,7 +258,7 @@ fn package_command_respects_ignore_files() {
     // in a git repository will be respected.
     fs::create_dir(fixture_dir.path().join(".git")).unwrap();
     let ignore_file = fixture_dir.path().join(".gitignore");
-    fs::write(ignore_file, "meta-buildpacks\nbuildpacks\n").unwrap();
+    fs::write(ignore_file, "composite-buildpacks\nbuildpacks\n").unwrap();
 
     let output = Command::new(CARGO_LIBCNB_BINARY_UNDER_TEST)
         .args(["libcnb", "package", "--release"])
@@ -281,7 +288,7 @@ fn validate_packaged_buildpack(packaged_buildpack_dir: &Path, buildpack_id: &Bui
     );
 }
 
-fn validate_packaged_meta_buildpack(
+fn validate_packaged_composite_buildpack(
     packaged_buildpack_dir: &Path,
     buildpack_id: &BuildpackId,
     expected_package_descriptor_dependencies: &[PackageDescriptorDependency],

libcnb-data/src/buildpack/mod.rs

@@ -19,8 +19,9 @@ pub use version::*;
 /// For parsing of [buildpack.toml](https://github.com/buildpacks/spec/blob/main/buildpack.md#buildpacktoml-toml)
 /// files when support for multiple types of buildpack is required.
 ///
-/// When a specific buildpack type is expected, use [`SingleBuildpackDescriptor`] or [`MetaBuildpackDescriptor`] directly instead,
-/// since it allows for more detailed error messages if parsing fails.
+/// When a specific buildpack type is expected, use [`ComponentBuildpackDescriptor`] or
+/// [`CompositeBuildpackDescriptor`] directly instead, since they allow for more detailed
+/// error messages if parsing fails.
 ///
 /// # Example:
 /// ```
@@ -49,40 +50,41 @@ pub use version::*;
 ///     toml::from_str::<BuildpackDescriptor>(toml_str)
 ///         .expect("buildpack.toml did not match a known type!");
 /// match buildpack_descriptor {
-///     BuildpackDescriptor::Single(buildpack) => {
-///         println!("Found buildpack: {}", buildpack.buildpack.id);
+///     BuildpackDescriptor::Component(buildpack) => {
+///         println!("Found component buildpack: {}", buildpack.buildpack.id);
 ///     }
-///     BuildpackDescriptor::Meta(buildpack) => {
-///         println!("Found meta-buildpack: {}", buildpack.buildpack.id);
+///     BuildpackDescriptor::Composite(buildpack) => {
+///         println!("Found composite buildpack: {}", buildpack.buildpack.id);
 ///     }
 /// };
 /// ```
 #[derive(Deserialize, Debug)]
 #[serde(untagged)]
 pub enum BuildpackDescriptor<BM = GenericMetadata> {
-    Single(SingleBuildpackDescriptor<BM>),
-    Meta(MetaBuildpackDescriptor<BM>),
+    Component(ComponentBuildpackDescriptor<BM>),
+    Composite(CompositeBuildpackDescriptor<BM>),
 }
 
 impl<BM> BuildpackDescriptor<BM> {
     pub fn buildpack(&self) -> &Buildpack {
         match self {
-            BuildpackDescriptor::Single(descriptor) => &descriptor.buildpack,
-            BuildpackDescriptor::Meta(descriptor) => &descriptor.buildpack,
+            BuildpackDescriptor::Component(descriptor) => &descriptor.buildpack,
+            BuildpackDescriptor::Composite(descriptor) => &descriptor.buildpack,
         }
     }
 }
 
-/// Data structure for the Buildpack descriptor (buildpack.toml) of a single buildpack.
+/// Data structure for the Buildpack descriptor (buildpack.toml) of a component buildpack.
 ///
 /// Representation of [buildpack.toml](https://github.com/buildpacks/spec/blob/main/buildpack.md#buildpacktoml-toml)
-/// when the buildpack is a single buildpack that implements the Buildpack Interface (ie: not a meta-buildpack).
+/// when the buildpack is a component buildpack - one that implements the Buildpack Interface
+/// (ie: contains `/bin/detect` and `/bin/build` executables).
 ///
 /// If support for multiple buildpack types is required, use [`BuildpackDescriptor`] instead.
 ///
 /// # Example:
 /// ```
-/// use libcnb_data::buildpack::{SingleBuildpackDescriptor, Stack};
+/// use libcnb_data::buildpack::{ComponentBuildpackDescriptor, Stack};
 /// use libcnb_data::buildpack_id;
 ///
 /// let toml_str = r#"
@@ -105,29 +107,31 @@ impl<BM> BuildpackDescriptor<BM> {
 /// "#;
 ///
 /// let buildpack_descriptor =
-///     toml::from_str::<SingleBuildpackDescriptor>(toml_str).unwrap();
+///     toml::from_str::<ComponentBuildpackDescriptor>(toml_str).unwrap();
 /// assert_eq!(buildpack_descriptor.buildpack.id, buildpack_id!("foo/bar"));
 /// assert_eq!(buildpack_descriptor.stacks, [Stack::Any]);
 /// ```
 #[derive(Deserialize, Debug)]
 #[serde(deny_unknown_fields)]
-pub struct SingleBuildpackDescriptor<BM = GenericMetadata> {
+pub struct ComponentBuildpackDescriptor<BM = GenericMetadata> {
     pub api: BuildpackApi,
     pub buildpack: Buildpack,
     pub stacks: Vec<Stack>,
     pub metadata: BM,
 }
 
-/// Data structure for the Buildpack descriptor (buildpack.toml) of a meta-buildpack.
+/// Data structure for the Buildpack descriptor (buildpack.toml) of a composite buildpack.
 ///
 /// Representation of [buildpack.toml](https://github.com/buildpacks/spec/blob/main/buildpack.md#buildpacktoml-toml)
-/// when the buildpack is a meta-buildpack.
+/// when the buildpack is a composite buildpack - one that does not implement the Buildpack Interface
+/// itself (ie: does not contain `/bin/detect` and `/bin/build` executables) but instead references
+/// other buildpacks via an order definition.
 ///
 /// If support for multiple buildpack types is required, use [`BuildpackDescriptor`] instead.
 ///
 /// # Example:
 /// ```
-/// use libcnb_data::buildpack::MetaBuildpackDescriptor;
+/// use libcnb_data::buildpack::CompositeBuildpackDescriptor;
 /// use libcnb_data::buildpack_id;
 ///
 /// let toml_str = r#"
@@ -153,12 +157,12 @@ pub struct SingleBuildpackDescriptor<BM = GenericMetadata> {
 /// "#;
 ///
 /// let buildpack_descriptor =
-///     toml::from_str::<MetaBuildpackDescriptor>(toml_str).unwrap();
+///     toml::from_str::<CompositeBuildpackDescriptor>(toml_str).unwrap();
 /// assert_eq!(buildpack_descriptor.buildpack.id, buildpack_id!("foo/bar"));
 /// ```
 #[derive(Deserialize, Debug)]
 #[serde(deny_unknown_fields)]
-pub struct MetaBuildpackDescriptor<BM = GenericMetadata> {
+pub struct CompositeBuildpackDescriptor<BM = GenericMetadata> {
     pub api: BuildpackApi,
     pub buildpack: Buildpack,
     pub order: Vec<Order>,
@@ -216,7 +220,7 @@ mod tests {
 
     #[test]
     #[allow(clippy::too_many_lines)]
-    fn deserialize_singlebuildpack() {
+    fn deserialize_component_buildpack() {
         let toml_str = r#"
 api = "0.9"
 
@@ -261,7 +265,8 @@ id = "*"
 checksum = "abc123"
         "#;
 
-        let buildpack_descriptor = toml::from_str::<SingleBuildpackDescriptor>(toml_str).unwrap();
+        let buildpack_descriptor =
+            toml::from_str::<ComponentBuildpackDescriptor>(toml_str).unwrap();
 
         assert_eq!(
             buildpack_descriptor.api,
@@ -343,7 +348,7 @@ checksum = "abc123"
     }
 
     #[test]
-    fn deserialize_metabuildpack() {
+    fn deserialize_composite_buildpack() {
         let toml_str = r#"
 api = "0.9"
 
@@ -381,7 +386,8 @@ optional = true
 checksum = "abc123"
         "#;
 
-        let buildpack_descriptor = toml::from_str::<MetaBuildpackDescriptor>(toml_str).unwrap();
+        let buildpack_descriptor =
+            toml::from_str::<CompositeBuildpackDescriptor>(toml_str).unwrap();
 
         assert_eq!(
             buildpack_descriptor.api,
@@ -453,7 +459,7 @@ checksum = "abc123"
     }
 
     #[test]
-    fn deserialize_minimal_singlebuildpack() {
+    fn deserialize_minimal_component_buildpack() {
         let toml_str = r#"
 api = "0.9"
 
@@ -465,7 +471,8 @@ version = "0.0.1"
 id = "*"
         "#;
 
-        let buildpack_descriptor = toml::from_str::<SingleBuildpackDescriptor>(toml_str).unwrap();
+        let buildpack_descriptor =
+            toml::from_str::<ComponentBuildpackDescriptor>(toml_str).unwrap();
 
         assert_eq!(
             buildpack_descriptor.api,
@@ -494,7 +501,7 @@ id = "*"
     }
 
     #[test]
-    fn deserialize_minimal_metabuildpack() {
+    fn deserialize_minimal_composite_buildpack() {
         let toml_str = r#"
 api = "0.9"
 
@@ -509,7 +516,8 @@ id = "foo/bar"
 version = "0.0.1"
 "#;
 
-        let buildpack_descriptor = toml::from_str::<MetaBuildpackDescriptor>(toml_str).unwrap();
+        let buildpack_descriptor =
+            toml::from_str::<CompositeBuildpackDescriptor>(toml_str).unwrap();
 
         assert_eq!(
             buildpack_descriptor.api,
@@ -546,7 +554,7 @@ version = "0.0.1"
     }
 
     #[test]
-    fn deserialize_buildpackdescriptor_single() {
+    fn deserialize_buildpackdescriptor_component() {
         let toml_str = r#"
 api = "0.9"
 
@@ -561,12 +569,12 @@ id = "*"
         let buildpack_descriptor = toml::from_str::<BuildpackDescriptor>(toml_str).unwrap();
         assert!(matches!(
             buildpack_descriptor,
-            BuildpackDescriptor::Single(_)
+            BuildpackDescriptor::Component(_)
         ));
     }
 
     #[test]
-    fn deserialize_buildpackdescriptor_meta() {
+    fn deserialize_buildpackdescriptor_composite() {
         let toml_str = r#"
 api = "0.9"
 
@@ -582,7 +590,10 @@ version = "0.0.1"
         "#;
 
         let buildpack_descriptor = toml::from_str::<BuildpackDescriptor>(toml_str).unwrap();
-        assert!(matches!(buildpack_descriptor, BuildpackDescriptor::Meta(_)));
+        assert!(matches!(
+            buildpack_descriptor,
+            BuildpackDescriptor::Composite(_)
+        ));
     }
 
     #[test]
@@ -610,10 +621,10 @@ version = "0.0.1"
             "data did not match any variant of untagged enum BuildpackDescriptor\n"
         );
 
-        let err = toml::from_str::<SingleBuildpackDescriptor>(toml_str).unwrap_err();
+        let err = toml::from_str::<ComponentBuildpackDescriptor>(toml_str).unwrap_err();
         assert!(err.to_string().contains("unknown field `order`"));
 
-        let err = toml::from_str::<MetaBuildpackDescriptor>(toml_str).unwrap_err();
+        let err = toml::from_str::<CompositeBuildpackDescriptor>(toml_str).unwrap_err();
         assert!(err.to_string().contains("unknown field `stacks`"));
     }
 }

libcnb-data/src/package_descriptor.rs

@@ -37,7 +37,9 @@ pub struct PackageDescriptor {
     /// The buildpack to package.
     pub buildpack: PackageDescriptorBuildpackReference,
 
-    /// A set of dependent buildpack locations, for packaging a meta-buildpack. Each dependent buildpack location must correspond to an order group within the meta-buildpack being packaged.
+    /// A set of dependent buildpack locations, for packaging a composite buildpack.
+    ///
+    /// Each dependent buildpack location must correspond to an order group within the composite buildpack being packaged.
     #[serde(default)]
     pub dependencies: Vec<PackageDescriptorDependency>,
 
@@ -62,6 +64,7 @@ impl Default for PackageDescriptor {
 #[serde(deny_unknown_fields)]
 pub struct PackageDescriptorBuildpackReference {
     /// A URL or path to an archive, or a path to a directory.
+    ///
     /// If the `uri` field is a relative path it will be relative to the `package.toml` file.
     #[serde(deserialize_with = "deserialize_uri_reference")]
     #[serde(serialize_with = "serialize_uri_reference")]
@@ -83,7 +86,7 @@ impl TryFrom<&str> for PackageDescriptorBuildpackReference {
     }
 }
 
-/// A dependent buildpack location for packaging a meta-buildpack.
+/// A dependent buildpack location for packaging a composite buildpack.
 #[derive(Debug, Deserialize, Serialize, Eq, PartialEq, Clone)]
 #[serde(deny_unknown_fields)]
 pub struct PackageDescriptorDependency {