feat(remote-build): add --project-dir argument to support build paths

docs/release-notes/snapcraft-9-0.rst

@@ -93,6 +93,11 @@ sources.
 Minor features
 --------------
 
+Custom build paths for remote build
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+The remote-build command now supports a ``--project-dir`` option to specify custom build paths for monorepo setups (`#6287`).
+
 Snapcraft 9.0 brings the following minor changes.
 
 Promote edge channels with ``--yes``

pyproject.toml

@@ -5,7 +5,7 @@ dynamic = ["version"]
 dependencies = [
     "catkin-pkg==1.1.0; sys_platform == 'linux'",
     "click>=8.3.3",
-    "craft-application[remote]>=7.1.0",
+    "craft-application[remote] @ git+https://github.com/canonical/craft-application.git@main",
     "craft-archives>=2.2.0",
     "craft-cli>=3.4.0",
     "craft-grammar>=2.3.0",

snapcraft/commands/remote.py

@@ -81,6 +81,14 @@ def _fill_parser(self, parser: argparse.ArgumentParser) -> None:
             dest="remote_build_build_fors",
         )
 
+        parser.add_argument(
+            "--project-dir",
+            type=str,
+            metavar="path",
+            help="Directory containing the snap project to build",
+            dest="project_dir",
+        )
+
     @override
     def _pre_build(self, parsed_args: argparse.Namespace):
         """Perform pre-build validation.
@@ -179,4 +187,9 @@ def _get_build_args(self, parsed_args: argparse.Namespace) -> dict[str, Any]:
             )
 
         emit.debug(f"Architectures to build for: {humanize_list(archs, 'and')}")
-        return {"architectures": archs}
+        build_args: dict[str, Any] = {"architectures": archs}
+
+        if getattr(parsed_args, "project_dir", None):
+            build_args["build_path"] = parsed_args.project_dir
+
+        return build_args

tests/spread/core24/remote-build/snaps/project-dir/arguments.txt

@@ -0,0 +1 @@
+--project-dir my-subdir

tests/spread/core24/remote-build/snaps/project-dir/expected-snaps.txt

@@ -0,0 +1 @@
+my-remote-snap_0.1_amd64.snap

tests/spread/core24/remote-build/snaps/project-dir/my-subdir/snapcraft.yaml

@@ -0,0 +1,11 @@
+name: my-remote-snap
+base: core24
+version: '0.1'
+summary: Test snap for project-dir remote build
+description: A minimal project to test remote builds using project-dir.
+grade: devel
+confinement: devmode
+
+parts:
+  my-part:
+    plugin: nil

tests/spread/core24/remote-build/task.yaml

@@ -14,6 +14,7 @@ environment:
   SNAP/build_for: build-for
   SNAP/build_for_with_platforms: build-for-with-platforms
   SNAP/build_for_with_shorthand_platforms: build-for-with-shorthand-platforms
+  SNAP/project_dir: project-dir
   CREDENTIALS_FILE: "$HOME/.local/share/snapcraft/launchpad-credentials"
 
 prepare: |
@@ -24,18 +25,20 @@ prepare: |
     exit 1
   fi
 
-  # commit the project
   git config --global --add safe.directory "$PWD"
   git init
-  git add snapcraft.yaml
+
+  if [[ -d "my-subdir" ]]; then
+    git add my-subdir/snapcraft.yaml
+  else
+    git add snapcraft.yaml
+  fi
+
   git commit -m "Initial Commit"
 
-  # set up launchpad token
   mkdir -p "$(dirname "$CREDENTIALS_FILE")"
   echo -e "$LAUNCHPAD_TOKEN" > "$CREDENTIALS_FILE"
 
-  # build ids are based on the project contents
-  # adding a date ensures each test has a unique build id
   date > date.txt
 
 restore: |
@@ -81,3 +84,4 @@ execute: |
       exit 1
     fi
   fi
+1

tests/unit/commands/test_remote.py

@@ -536,7 +536,7 @@ def test_unknown_build_for_error(
     ],
 )
 @pytest.mark.usefixtures("emitter", "mock_argv", "mock_remote_start_builds")
-def test_multiple_artifacts_per_build_on(
+def test_multiple_artifacts_per_build_on( # noqa: PLR0917
     default_project,
     fake_services,
     setup_project,
@@ -567,3 +567,37 @@ def test_multiple_artifacts_per_build_on(
     )
     for message in error_messages:
         check.is_in(message, err)
+
+
+@pytest.mark.usefixtures("emitter")
+def test_project_dir_argument(
+    default_project,
+    fake_services,
+    setup_project,
+    mock_remote_start_builds,
+    fake_app,
+    mocker,
+):
+    """Test that `--project-dir` passes the build_path argument."""
+    mocker.patch.object(
+        sys,
+        "argv",
+        [
+            "snapcraft",
+            "remote-build",
+            "--launchpad-accept-public-upload",
+            "--project-dir",
+            "my-subdir",
+        ],
+    )
+    setup_project(
+        fake_services,
+        {**default_project.marshal(), "base": "core24"},
+        write_project=True,
+    )
+
+    fake_app.run()
+
+    mock_remote_start_builds.assert_called_once_with(
+        ANY, architectures=[str(DebianArchitecture.from_host())], build_path="my-subdir"
+    )