feat: set crane as default resolver

README.md

@@ -6,8 +6,7 @@ Tooling that enables software release pipelines for operator manifests.
 
 ### Binaries
 
-Binaries are available for Linux (amd64, s390x, ppc64le, and arm64) and Darwin (amd64). This tool doesn't require skopeo to function
-but to not use skopeo is definitely the harder path. If you require the library on an unsupported OS we recommend you use the docker images.
+Binaries are available for Linux (amd64, s390x, ppc64le, and arm64) and Darwin (amd64). This tool bundles the [crane resolver](https://github.com/google/go-containerregistry/blob/main/cmd/crane/doc/crane.md)and uses it by default. Use of alternate or even custom image resolvers is available; please see the sections below.
 
 ### Docker
 
@@ -62,7 +61,10 @@ operator-manifest-tools pinning pin $MANIFEST_DIR
 # equalivent to pin; doesn't generate temporary files for the cmd though
 operator-manifest-tools pinning extract $MANIFEST_DIR - | operator-manifest-tools pinning resolve - | operator-manifest-tools pinning replace $MANIFEST_DIR
 ```
+#### Using alternate resolvers
+
+If the built in `crane` resolver is causing issues, there is a built in alternate skopeo resolver. It requires the [skopeo](https://github.com/containers/skopeo) binary to be on the host machine. Just run the commands with the option `--resolver skopeo`
 
 #### Custom Resolve Scripts
 
-It's possible to replace skopeo with other resolve mechanisms (i.e. docker). The resolve and pin command can take parameters that will override the skopeo default with a script. Please see [hack/resolvers/skopeo.sh](hack/resolvers/skopeo.sh) for an example using skopeo.
+It's possible to replace skopeo with other resolve mechanisms (i.e. docker). The resolve and pin command can take parameters that will override the crane default with a script. Please see [hack/resolvers/skopeo.sh](hack/resolvers/skopeo.sh) for an example using skopeo.

cmd/pinning/resolve.go

@@ -120,7 +120,7 @@ func mountResolverOpts(
 	}
 
 	cmd.Flags().StringVarP(resolverVar,
-		"resolver", "r", "skopeo",
+		"resolver", "r", "crane",
 		fmt.Sprintf("The resolver to use; valid values are [%s]", imageresolver.GetResolverOptions()))
 
 	cmd.Flags().StringToStringVar(resolverArgs,

internal/tests/integration/test.py

@@ -60,7 +60,7 @@ def assert_output_files_have_expected_content(testing_pullspecs):
         else:
             assert pullspec['original'] in references_content
 
-
+ 
 class TestPinCommand():
 
     # def test_version(self, teardown, tmp_path):
@@ -70,7 +70,7 @@ class TestPinCommand():
 
     def test_manifest_dir_empty(self, teardown, tmp_path):
         cmd = subprocess.run(['operator-manifest-tools', 'pinning', 'pin', tmp_path], capture_output=True)
-        print({"err": cmd.stderr, "output":cmd.stderr})
+        print({"err": cmd.stderr, "output": cmd.stderr})
         assert 'Missing ClusterServiceVersion in operator manifests' in str(cmd.stderr)
         assert_output_files_are_empty()
 
@@ -264,7 +264,8 @@ def test_nonexistent_image(self, csv_filename, teardown, tmp_path):
         cmd = subprocess.run(['operator-manifest-tools', 'pinning', 'pin', tmp_path], capture_output=True)
         err_msg = "Failed to inspect docker://quay.io/containerbuildsystem/operator-manifest-test-image:nonexistenttag." \
                   " Make sure it exists and is accessible."
-        assert err_msg in str(cmd.stderr)
+        err_msg_alt = "manifest unknown"
+        assert err_msg in str(cmd.stderr) or err_msg_alt in str(cmd.stderr)
 
     @pytest.mark.parametrize('csv_filename', ['related_images_defined_on_both_places_csv.yaml'])
     def test_manifests_having_related_images_defined_on_both_places(self, csv_filename, teardown, tmp_path):