Add shortname ambiguity warning in shortcut expander (#117668)

* Add warning handler callback function in shortcut expander

Currently, errors in client-go are propagated back to the callers via
function returns. However, there is no elegant way for just warning users.
For example, when user wants to get a resource with it's short name format
and if there are multiple resources belonging to this short name, we need to
warn user about this ambugity which one is picked and which ones are discarded.

Not only to overcome this particular case mentioned above, but also propose a
way for the possible warnings in the future, this commit adds a warningHandler
callback function in shortcutExpander.

* Add warningPrinter functionality in ConfigFlags

ConfigFlags has neither warning user in a standardized
format functionality nor passing warning callback functions to other upper level
libraries such as client-go.

This commit adds an ability that user can set warningPrinters
according to their IOStreams and this warningPrinters will be used
to raise possible warnings happening not only in cli-runtime but
also in client-go.

* Pass warning callback function in ConfigFlags to shortcutExpander

This commit passes warning callback function to print possible
warnings happened in shortcut expander to warn user in a
standardized format.

* Add integration test for CRDs having ambiguous short names

This commit adds integration test to assure that warning message
related to this ambiguity is printed when resources are being retrieved via their short name
representations in cases where multiple resources have same
short names.

This integration test also ensures that the logic behind which resource
will be selected hasn't been changed which may cause disperancies in
clusters.

* Remove defaultConfigFlag global variable

* Move default config flags initialization into function

* Skip warning for versions of same group/resource

* Run update-vendor

* Warn only once when there are multiple versions registered for ambiguous resource

* Apply gocritic review

* Add multi-resource multi-version ambiguity unit test

test/cmd/discovery.sh

@@ -303,3 +303,107 @@ run_swagger_tests() {
   set +o nounset
   set +o errexit
 }
+
+run_ambiguous_shortname_tests() {
+  set -o nounset
+  set -o errexit
+
+  create_and_use_new_namespace
+  kube::log::status "Testing ambiguous short name"
+
+  kubectl create -f - << __EOF__
+apiVersion: apiextensions.k8s.io/v1
+kind: CustomResourceDefinition
+metadata:
+  name: foos.bar.com
+spec:
+  group: bar.com
+  scope: Namespaced
+  versions:
+    - name: v1
+      served: true
+      storage: true
+      schema:
+        openAPIV3Schema:
+          type: object
+          properties:
+            spec:
+              type: object
+              properties:
+                test:
+                  type: string
+  names:
+    plural: foos
+    singular: foo
+    shortNames:
+      - exmp
+    kind: Foo
+    categories:
+      - all
+__EOF__
+
+  # Test that we can list this new custom resource
+  kube::test::wait_object_assert customresourcedefinitions "{{range.items}}{{if eq ${id_field:?} \"foos.bar.com\"}}{{$id_field}}:{{end}}{{end}}" 'foos.bar.com:'
+
+  kubectl create -f - << __EOF__
+apiVersion: bar.com/v1
+kind: Foo
+metadata:
+  name: test-crd-foo
+spec:
+  test: test
+__EOF__
+
+  # Test that we can list this new custom resource
+  kube::test::wait_object_assert foos "{{range.items}}{{$id_field}}:{{end}}" 'test-crd-foo:'
+
+  output_message=$(kubectl get exmp)
+  kube::test::if_has_string "${output_message}" "test-crd-foo"
+
+  kubectl create -f - << __EOF__
+apiVersion: apiextensions.k8s.io/v1
+kind: CustomResourceDefinition
+metadata:
+  name: examples.test.com
+spec:
+  group: test.com
+  scope: Namespaced
+  versions:
+    - name: v1
+      served: true
+      storage: true
+      schema:
+        openAPIV3Schema:
+          type: object
+          properties:
+            spec:
+              type: object
+              properties:
+                test:
+                  type: string
+  names:
+    plural: examples
+    singular: example
+    shortNames:
+      - exmp
+    kind: Example
+__EOF__
+
+  # Test that we can list this new custom resource
+  kube::test::wait_object_assert customresourcedefinitions "{{range.items}}{{if eq ${id_field:?} \"examples.test.com\"}}{{$id_field}}:{{end}}{{end}}" 'examples.test.com:'
+
+  output_message=$(kubectl  get examples 2>&1 "${kube_flags[@]}")
+  kube::test::if_has_string "${output_message}" 'No resources found'
+
+  output_message=$(kubectl get exmp 2>&1)
+  kube::test::if_has_string "${output_message}" "test-crd-foo"
+  kube::test::if_has_string "${output_message}" "short name \"exmp\" could also match lower priority resource examples.test.com"
+
+  # Cleanup
+  kubectl delete foos/test-crd-foo
+  kubectl delete customresourcedefinition foos.bar.com
+  kubectl delete customresourcedefinition examples.test.com
+
+  set +o nounset
+  set +o errexit
+}

test/cmd/legacy-script.sh

@@ -518,6 +518,14 @@ runTests() {
     record_command run_assert_singular_name_tests
   fi
 
+  #########################
+  # Ambiguous short name  #
+  #########################
+
+  if kube::test::if_supports_resource "${customresourcedefinitions}" ; then
+    record_command run_ambiguous_shortname_tests
+  fi
+
   #########################
   # Assert categories     #
   #########################