Merge pull request timfeirg#39 from agavemindlab/dev-38-builds-schema-defaults

- Apply BuildSchema defaults (workdir, script) for builds: (plural) config
- Derive defaults dynamically from BuildSchema.model_fields to prevent drift
- 1 new regression test

Reviews: APPROVED by gl-swe (2 rounds)
Fixes: timfeirg#38

Author: hongqn

lain_cli/utils.py

@@ -1142,7 +1142,26 @@ def tell_builds():
     if has_build and has_builds:
         error("cannot define both 'build' and 'builds' in values.yaml", exit=1)
     if has_builds:
-        return dict(getattr(values, "builds"))
+        from pydantic.fields import PydanticUndefined
+
+        from lain_cli.schemas import BuildSchema
+
+        result = {}
+        for name, bc in getattr(values, "builds").items():
+            bc = dict(bc)
+            # Apply BuildSchema defaults for fields that have defaults
+            for field_name, field_info in BuildSchema.model_fields.items():
+                if field_name in bc:
+                    continue
+                if field_info.default_factory is not None:
+                    bc[field_name] = field_info.default_factory()
+                elif (
+                    field_info.default is not PydanticUndefined
+                    and field_info.default is not None
+                ):
+                    bc[field_name] = field_info.default
+            result[name] = bc
+        return result
     if has_build:
         build_clause = values.build.model_dump(
             mode="python", by_alias=True, exclude_none=True

tests/test_multi_build.py

@@ -6,6 +6,7 @@
 
 from lain_cli.utils import (
     DEFAULT_BUILD_NAME,
+    DEFAULT_WORKDIR,
     context,
     make_image_str,
     tell_build_deps,
@@ -716,3 +717,26 @@ def test_image_repos_no_build():
     yadu(values, DUMMY_VALUES_PATH)
     res = run(lain, args=["image-repos"])
     assert DUMMY_APPNAME in res.output.strip()
+
+
+@pytest.mark.usefixtures("dummy_helm_chart")
+def test_builds_plural_applies_schema_defaults():
+    """builds: (plural) should apply BuildSchema defaults like workdir."""
+    values = load_dummy_values()
+    del values["build"]
+    # Omit workdir — BuildSchema should default it to /lain/app
+    values["builds"] = {
+        "default": {"base": "python:3.12", "script": ["echo ok"]},
+        "gpu": {"base": "nvidia/cuda:12.6", "script": ["echo gpu"]},
+    }
+    yadu(values, DUMMY_VALUES_PATH)
+
+    def check_defaults():
+        builds = tell_builds()
+        for name, bc in builds.items():
+            assert bc.get("workdir") == DEFAULT_WORKDIR, (
+                f"build '{name}' missing workdir default"
+            )
+            assert bc.get("script") is not None
+
+    run_under_click_context(check_defaults)