feat: report fetch-service rejections

When creating the Craft manifest the FetchService will now also print a report
of those dependencies that were rejected by the fetch-service. This includes
the dependencies' urls and the list of rejection reasons.

Fixes #3539

craft_application/services/fetch.py

@@ -20,12 +20,13 @@
 import pathlib
 import subprocess
 import typing
+from functools import partial
 
 import craft_providers
 from craft_cli import emit
 from typing_extensions import override
 
-from craft_application import fetch, models, services
+from craft_application import fetch, models, services, util
 from craft_application.models.manifest import CraftManifest, ProjectManifest
 
 if typing.TYPE_CHECKING:
@@ -173,3 +174,21 @@ def _create_craft_manifest(
 
         with manifest_path.open("w") as f:
             json.dump(data, f, ensure_ascii=False, indent=2)
+
+        deps = craft_manifest.dependencies
+        rejections = [dep for dep in deps if dep.rejected]
+
+        if rejections:
+            display = partial(emit.progress, permanent=True)
+            items: list[dict[str, typing.Any]] = []
+            for rejection in rejections:
+                url = rejection.url[0] if len(rejection.url) == 1 else rejection.url
+                items.append({"url": url, "reasons": rejection.rejection_reasons})
+            text = util.dump_yaml(items)
+
+            display(
+                "The following artifacts were marked as rejected by the fetch-service:"
+            )
+            for line in text.splitlines():
+                display(line)
+            display("This build will fail on 'strict' fetch-service sessions.")

tests/unit/services/test_fetch.py

@@ -25,6 +25,7 @@
 import contextlib
 import json
 import re
+import textwrap
 from datetime import datetime
 from unittest import mock
 from unittest.mock import MagicMock, call
@@ -108,7 +109,13 @@ def test_create_project_manifest_not_managed(fetch_service, tmp_path, monkeypatc
 
 
 def test_teardown_session_create_manifest(
-    fetch_service, tmp_path, mocker, manifest_data_dir, monkeypatch, fake_project
+    fetch_service,
+    tmp_path,
+    mocker,
+    manifest_data_dir,
+    monkeypatch,
+    fake_project,
+    emitter,
 ):
     monkeypatch.chdir(tmp_path)
 
@@ -142,6 +149,27 @@ def temporarily_pull_file(*, source, missing_ok):
 
     assert obtained_file.read_text() + "\n" == expected_file.read_text()
 
+    expected_output = textwrap.dedent(
+        """\
+        The following artifacts were marked as rejected by the fetch-service:
+        - url: https://github.com:443/canonical/sphinx-docs-starter-pack.git/git-upload-pack
+          reasons:
+          - fetch is allowed only on a single ref
+          - fetch is only allowed with depth 1
+          - git repository does not contain a go.mod file
+        - url: https://proxy.golang.org:443/github.com/go-mmap/mmap/@v/v0.7.0.mod
+          reasons:
+          - the artefact format is unknown
+          - the request was not recognized by any format inspector
+        This build will fail on 'strict' fetch-service sessions.
+        """
+    )
+    for line in expected_output.splitlines():
+        emitter.assert_progress(
+            line,
+            permanent=True,
+        )
+
 
 @pytest.mark.parametrize("run_on_host", [True, False])
 def test_warning_experimental(mocker, fetch_service, run_on_host, emitter):