feat: allow for multi-base builds (#598)

Signed-off-by: Callahan Kovacs <callahan.kovacs@canonical.com>

Author: mr-cal

craft_application/models/project.py

@@ -43,7 +43,6 @@
     UniqueStrList,
     VersionStr,
 )
-from craft_application.util import is_valid_architecture
 
 
 @dataclasses.dataclass
@@ -131,13 +130,14 @@ def _vectorise_architectures(cls, values: str | list[str]) -> list[str]:
     @pydantic.field_validator("build_on", "build_for", mode="after")
     @classmethod
     def _validate_architectures(cls, values: list[str]) -> list[str]:
-        """Validate the architecture entries."""
-        for architecture in values:
-            if architecture != "all" and not is_valid_architecture(architecture):
-                raise errors.CraftValidationError(
-                    f"Invalid architecture: {architecture!r} "
-                    "must be a valid debian architecture."
-                )
+        """Validate the architecture entries.
+
+        Entries must be a valid debian architecture or 'all'. Architectures may
+        be preceded by an optional base prefix formatted as '[<base>:]<arch>'.
+
+        :raises ValueError: If any of the bases or architectures are not valid.
+        """
+        [craft_platforms.parse_base_and_architecture(arch) for arch in values]
 
         return values
 
@@ -167,8 +167,10 @@ def from_platforms(cls, platforms: craft_platforms.Platforms) -> dict[str, Self]
         return result
 
 
-def _populate_platforms(platforms: dict[str, Any]) -> dict[str, Any]:
-    """Populate empty platform entries.
+def _expand_shorthand_platforms(platforms: dict[str, Any]) -> dict[str, Any]:
+    """Expand shorthand platform entries into standard form.
+
+    Assumes the platform label is a valid as a build-on and build-for entry.
 
     :param platforms: The platform data.
 
@@ -211,8 +213,8 @@ def _warn_deprecation(self) -> Self:
     @pydantic.field_validator("platforms", mode="before")
     @classmethod
     def _populate_platforms(cls, platforms: dict[str, Any]) -> dict[str, Any]:
-        """Populate empty platform entries."""
-        return _populate_platforms(platforms)
+        """Expand shorthand platform entries into standard form."""
+        return _expand_shorthand_platforms(platforms)
 
     @pydantic.field_validator("platforms", mode="after")
     @classmethod
@@ -233,9 +235,9 @@ def _validate_platforms_all_keyword(
 
         # validate `all` inside each platform:
         for platform in platforms.values():
-            if platform.build_on and "all" in platform.build_on:
+            if platform and platform.build_on and "all" in platform.build_on:
                 raise ValueError("'all' cannot be used for 'build-on'")
-            if platform.build_for and "all" in platform.build_for:
+            if platform and platform.build_for and "all" in platform.build_for:
                 is_all_used = True
 
         # validate `all` across all platforms:
@@ -337,8 +339,8 @@ class Project(base.CraftBaseModel):
     @pydantic.field_validator("platforms", mode="before")
     @classmethod
     def _populate_platforms(cls, platforms: dict[str, Platform]) -> dict[str, Platform]:
-        """Populate empty platform entries."""
-        return _populate_platforms(platforms)
+        """Expand shorthand platform entries into standard form."""
+        return _expand_shorthand_platforms(platforms)
 
     @property
     def effective_base(self) -> Any:  # noqa: ANN401 app specific classes can improve

docs/reference/changelog.rst

@@ -4,6 +4,14 @@
 Changelog
 *********
 
+4.7.0 (2024-Dec-19)
+-------------------
+
+Application
+===========
+
+- Allow applications to implement multi-base build plans.
+
 4.6.0 (2024-Dec-13)
 -------------------
 

pyproject.toml

@@ -8,7 +8,7 @@ dependencies = [
     "craft-cli>=2.12.0",
     "craft-grammar>=2.0.0",
     "craft-parts>=2.1.1",
-    "craft-platforms>=0.3.1",
+    "craft-platforms>=0.5.0",
     "craft-providers>=2.0.4",
     "Jinja2~=3.1",
     "snap-helpers>=0.4.2",

tests/unit/models/test_project.py

@@ -35,7 +35,6 @@
     Project,
     constraints,
 )
-from craft_application.util import platforms
 
 PROJECTS_DIR = pathlib.Path(__file__).parent / "project_models"
 PARTS_DICT = {"my-part": {"plugin": "nil"}}
@@ -170,15 +169,15 @@ def test_build_info_from_platforms(incoming, expected):
                 Platform(build_on=[arch], build_for=[arch]),
                 id=arch,
             )
-            for arch in platforms._ARCH_TRANSLATIONS_DEB_TO_PLATFORM
+            for arch in craft_platforms.DebianArchitecture
         ),
         *(
             pytest.param(
                 {"build-on": arch},
                 Platform(build_on=[arch]),
                 id=f"build-on-only-{arch}",
             )
-            for arch in platforms._ARCH_TRANSLATIONS_DEB_TO_PLATFORM
+            for arch in craft_platforms.DebianArchitecture
         ),
         pytest.param(
             {"build-on": "amd64", "build-for": "riscv64"},
@@ -562,30 +561,39 @@ def test_unmarshal_invalid_repositories(
 
 
 @pytest.mark.parametrize("model", [Project, BuildPlanner])
-def test_platform_invalid_arch(model, basic_project_dict):
-    basic_project_dict["platforms"] = {"unknown": None}
+@pytest.mark.parametrize("platform_label", ["unknown", "ubuntu@24.04:unknown"])
+def test_platform_invalid_arch(model, platform_label, basic_project_dict):
+    basic_project_dict["platforms"] = {platform_label: None}
     project_path = pathlib.Path("myproject.yaml")
 
     with pytest.raises(CraftValidationError) as error:
         model.from_yaml_data(basic_project_dict, project_path)
 
     assert error.value.args[0] == (
-        "Invalid architecture: 'unknown' must be a valid debian architecture."
+        "Bad myproject.yaml content:\n"
+        f"- 'unknown' is not a valid DebianArchitecture (in field 'platforms.{platform_label}.build-on')\n"
+        f"- 'unknown' is not a valid DebianArchitecture (in field 'platforms.{platform_label}.build-for')"
     )
 
 
 @pytest.mark.parametrize("model", [Project, BuildPlanner])
+@pytest.mark.parametrize("arch", ["unknown", "ubuntu@24.04:unknown"])
 @pytest.mark.parametrize("field_name", ["build-on", "build-for"])
-def test_platform_invalid_build_arch(model, field_name, basic_project_dict):
-    basic_project_dict["platforms"] = {"amd64": {field_name: ["unknown"]}}
+def test_platform_invalid_build_arch(model, arch, field_name, basic_project_dict):
+    basic_project_dict["platforms"] = {"amd64": {field_name: [arch]}}
     project_path = pathlib.Path("myproject.yaml")
 
     with pytest.raises(CraftValidationError) as error:
         model.from_yaml_data(basic_project_dict, project_path)
 
-    assert error.value.args[0] == (
-        "Invalid architecture: 'unknown' must be a valid debian architecture."
-    )
+    error_lines = [
+        "Bad myproject.yaml content:",
+        "- field 'build-on' required in 'platforms.amd64' configuration",
+        f"- 'unknown' is not a valid DebianArchitecture (in field 'platforms.amd64.{field_name}')",
+    ]
+    if field_name == "build-on":
+        error_lines.pop(1)
+    assert error.value.args[0] == "\n".join(error_lines)
 
 
 @pytest.mark.parametrize(