fix(provider): forward proxy variables to core24 build environments

Forward `http_proxy`, `https_proxy`, and `no_proxy` to core24 build
environments.

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

snapcraft/const.py

@@ -47,3 +47,13 @@ def __str__(self) -> str:
 
 CURRENT_BASES = frozenset(BASES - ESM_BASES - LEGACY_BASES)
 """Bases handled by the current snapcraft codebase."""
+
+
+SNAPCRAFT_ENVIRONMENT_VARIABLES = frozenset(
+    {
+        "SNAPCRAFT_BUILD_INFO",
+        "SNAPCRAFT_IMAGE_INFO",
+        "SNAPCRAFT_ENABLE_EXPERIMENTAL_EXTENSIONS",
+    }
+)
+"""Snapcraft-specific environment variables."""

snapcraft/services/provider.py

@@ -20,19 +20,16 @@
 from craft_application import ProviderService
 from overrides import overrides
 
+from snapcraft.const import SNAPCRAFT_ENVIRONMENT_VARIABLES
+
 
 class Provider(ProviderService):
     """Snapcraft specialization of the Lifecycle Service."""
 
     @overrides
     def setup(self) -> None:
-        if build_info := os.getenv("SNAPCRAFT_BUILD_INFO"):
-            self.environment["SNAPCRAFT_BUILD_INFO"] = build_info
-        if image_info := os.getenv("SNAPCRAFT_IMAGE_INFO"):
-            self.environment["SNAPCRAFT_IMAGE_INFO"] = image_info
-        if experimental_extensions := os.getenv(
-            "SNAPCRAFT_ENABLE_EXPERIMENTAL_EXTENSIONS"
-        ):
-            self.environment["SNAPCRAFT_ENABLE_EXPERIMENTAL_EXTENSIONS"] = (
-                experimental_extensions
-            )
+        """Add snapcraft environment variables to the build environment."""
+        super().setup()
+        for variable in SNAPCRAFT_ENVIRONMENT_VARIABLES:
+            if variable in os.environ:
+                self.environment[variable] = os.environ[variable]

tests/unit/services/test_provider.py

@@ -16,15 +16,19 @@
 
 """Tests for the Snapcraft provider service."""
 
+from craft_application.services.provider import DEFAULT_FORWARD_ENVIRONMENT_VARIABLES
+
+from snapcraft.const import SNAPCRAFT_ENVIRONMENT_VARIABLES
+
 
 def test_provider(provider_service, monkeypatch):
-    monkeypatch.setenv("SNAPCRAFT_BUILD_INFO", "foo")
-    monkeypatch.setenv("SNAPCRAFT_IMAGE_INFO", "bar")
-    monkeypatch.setenv("SNAPCRAFT_ENABLE_EXPERIMENTAL_EXTENSIONS", "baz")
-    provider_service.setup()
-    assert provider_service.environment["SNAPCRAFT_BUILD_INFO"] == "foo"
-    assert provider_service.environment["SNAPCRAFT_IMAGE_INFO"] == "bar"
-    assert (
-        provider_service.environment["SNAPCRAFT_ENABLE_EXPERIMENTAL_EXTENSIONS"]
-        == "baz"
+    variables = SNAPCRAFT_ENVIRONMENT_VARIABLES | set(
+        DEFAULT_FORWARD_ENVIRONMENT_VARIABLES
     )
+    for variable in variables:
+        monkeypatch.setenv(variable, f"{variable}-test-value")
+
+    provider_service.setup()
+
+    for variable in variables:
+        assert provider_service.environment[variable] == f"{variable}-test-value"