fix: use correct parallel build count

.github/workflows/security-scan.yaml

@@ -0,0 +1,15 @@
+name: Security scan
+on:
+  pull_request:
+  push:
+    branches:
+      - main
+      - hotfix/*
+      - work/secscan  # For development
+
+jobs:
+  python-scans:
+    name: Scan Python project
+    uses: canonical/starflow/.github/workflows/scan-python.yaml@main
+    with:
+      packages: python-apt-dev

.github/workflows/tests.yaml

@@ -60,10 +60,6 @@ jobs:
             3.10
             3.12
           cache: 'pip'
-      - name: Setup LXD
-        uses: canonical/setup-lxd@v0.1.1
-        with:
-          channel: latest/stable
       - name: Configure environment
         run: |
           echo "::group::apt-get"
@@ -111,10 +107,12 @@ jobs:
           cache: 'pip'
       - name: Setup LXD
         uses: canonical/setup-lxd@v0.1.1
-        with:
-          channel: latest/stable
       - name: Configure environment
         run: |
+          echo "::group::Begin snap install"
+          echo "Installing snaps in the background while running apt and pip..."
+          sudo snap install --no-wait --channel=beta fetch-service
+          echo "::endgroup::"
           echo "::group::apt-get"
           sudo apt update
           sudo apt-get install -y libapt-pkg-dev
@@ -123,6 +121,9 @@ jobs:
           python -m pip install tox
           echo "::endgroup::"
           mkdir -p results
+          echo "::group::Wait for snap to complete"
+          snap watch --last=install
+          echo "::endgroup::"
       - name: Setup Tox environments
         run: tox run -e integration-${{ matrix.python }} --notest
       - name: Integration tests

craft_application/application.py

@@ -156,6 +156,11 @@ def __init__(
         else:
             self._work_dir = pathlib.Path.cwd()
 
+        # Whether the command execution should use the fetch-service
+        self._use_fetch_service = False
+        # The kind of sessions that the fetch-service service should create
+        self._fetch_service_policy = "strict"
+
     @property
     def app_config(self) -> dict[str, Any]:
         """Get the configuration passed to dispatcher.load_command().
@@ -238,6 +243,11 @@ def _configure_services(self, provider_name: str | None) -> None:
             build_plan=self._build_plan,
             provider_name=provider_name,
         )
+        self.services.update_kwargs(
+            "fetch",
+            build_plan=self._build_plan,
+            session_policy=self._fetch_service_policy,
+        )
 
     def _resolve_project_path(self, project_dir: pathlib.Path | None) -> pathlib.Path:
         """Find the project file for the current project.
@@ -368,8 +378,14 @@ def run_managed(self, platform: str | None, build_for: str | None) -> None:
             instance_path = pathlib.PosixPath("/root/project")
 
             with self.services.provider.instance(
-                build_info, work_dir=self._work_dir
+                build_info,
+                work_dir=self._work_dir,
+                clean_existing=self._use_fetch_service,
             ) as instance:
+                if self._use_fetch_service:
+                    session_env = self.services.fetch.create_session(instance)
+                    env.update(session_env)
+
                 cmd = [self.app.name, *sys.argv[1:]]
                 craft_cli.emit.debug(
                     f"Executing {cmd} in instance location {instance_path} with {extra_args}."
@@ -387,6 +403,12 @@ def run_managed(self, platform: str | None, build_for: str | None) -> None:
                     raise craft_providers.ProviderError(
                         f"Failed to execute {self.app.name} in instance."
                     ) from exc
+                finally:
+                    if self._use_fetch_service:
+                        self.services.fetch.teardown_session()
+
+        if self._use_fetch_service:
+            self.services.fetch.shutdown(force=True)
 
     def configure(self, global_args: dict[str, Any]) -> None:
         """Configure the application using any global arguments."""
@@ -482,12 +504,14 @@ def _pre_run(self, dispatcher: craft_cli.Dispatcher) -> None:
         At the time this is run, the command is loaded in the dispatcher, but
         the project has not yet been loaded.
         """
+        args = dispatcher.parsed_args()
+
         # Some commands might have a project_dir parameter. Those commands and
         # only those commands should get a project directory, but only when
         # not managed.
         if self.is_managed():
             self.project_dir = pathlib.Path("/root/project")
-        elif project_dir := getattr(dispatcher.parsed_args(), "project_dir", None):
+        elif project_dir := getattr(args, "project_dir", None):
             self.project_dir = pathlib.Path(project_dir).expanduser().resolve()
             if self.project_dir.exists() and not self.project_dir.is_dir():
                 raise errors.ProjectFileMissingError(
@@ -496,6 +520,11 @@ def _pre_run(self, dispatcher: craft_cli.Dispatcher) -> None:
                     resolution="Ensure the path entered is correct.",
                 )
 
+        fetch_service_policy: str | None = getattr(args, "fetch_service_policy", None)
+        if fetch_service_policy:
+            self._use_fetch_service = True
+            self._fetch_service_policy = fetch_service_policy
+
     def get_arg_or_config(
         self, parsed_args: argparse.Namespace, item: str
     ) -> Any:  # noqa: ANN401
@@ -682,6 +711,7 @@ def _expand_environment(self, yaml_data: dict[str, Any], build_for: str) -> None
             application_name=self.app.name,  # not used in environment expansion
             cache_dir=pathlib.Path(),  # not used in environment expansion
             arch=build_for_arch,
+            parallel_build_count=util.get_parallel_build_count(self.app.name),
             project_name=yaml_data.get("name", ""),
             project_dirs=project_dirs,
             project_vars=environment_vars,

craft_application/commands/lifecycle.py

@@ -14,21 +14,19 @@
 """Basic lifecycle commands for a Craft Application."""
 from __future__ import annotations
 
+import argparse
 import os
 import pathlib
 import subprocess
 import textwrap
-from typing import TYPE_CHECKING, Any
+from typing import Any
 
 from craft_cli import CommandGroup, emit
 from craft_parts.features import Features
 from typing_extensions import override
 
 from craft_application.commands import base
 
-if TYPE_CHECKING:  # pragma: no cover
-    import argparse
-
 
 def get_lifecycle_command_group() -> CommandGroup:
     """Return the lifecycle related command group."""
@@ -355,6 +353,14 @@ def _fill_parser(self, parser: argparse.ArgumentParser) -> None:
             help="Output directory for created packages.",
         )
 
+        parser.add_argument(
+            "--use-fetch-service",
+            help=argparse.SUPPRESS,
+            choices=("strict", "permissive"),
+            metavar="policy",
+            dest="fetch_service_policy",
+        )
+
     @override
     def _run(
         self,
@@ -392,6 +398,9 @@ def _run(
                 _launch_shell()
             raise
 
+        if parsed_args.fetch_service_policy and packages:
+            self._services.fetch.create_project_manifest(packages)
+
         if not packages:
             emit.progress("No packages created.", permanent=True)
         elif len(packages) == 1:
@@ -427,6 +436,12 @@ def _fill_parser(self, parser: argparse.ArgumentParser) -> None:
             nargs="*",
             help="Optional list of parts to process",
         )
+        parser.add_argument(
+            "--platform",
+            type=str,
+            metavar="name",
+            help="Platform to clean",
+        )
 
     @override
     def _run(

craft_application/errors.py

@@ -242,3 +242,7 @@ def __init__(  # (too many arguments)
             reportable=reportable,
             retcode=retcode,
         )
+
+
+class FetchServiceError(CraftError):
+    """Errors related to the fetch-service."""