Add support for dry run (ansible-collections#245)

Add support for dry run

SUMMARY

Kubernetes server-side dry run will be used when the kubernetes client
version is >=18.20.0. For older versions of the client, the existing
client side speculative change implementation will be used.
The effect of this change should be mostly transparent to the end user
and is reflected in the fact the tests have not changed but should still
pass. With this change, there are a few edge cases that will be
improved. One example of these edge cases is to use check mode on an
existing Service resource. With dry run this will correctly report no
changes, while the older client side implementation will erroneously
report changes to the port spec.

ISSUE TYPE


Feature Pull Request

COMPONENT NAME

ADDITIONAL INFORMATION

Reviewed-by: Gonéri Le Bouder <goneri@lebouder.net>
Reviewed-by: Mike Graves <mgraves@redhat.com>
Reviewed-by: Alina Buzachis <None>
Reviewed-by: None <None>
Reviewed-by: None <None>

changelogs/fragments/245-add-dry-run.yaml

@@ -0,0 +1,3 @@
+---
+minor_changes:
+  - add support for dry run with kubernetes client version >=18.20 (https://github.com/ansible-collections/kubernetes.core/pull/245).

molecule/default/tasks/full.yml

@@ -60,11 +60,16 @@
           environment:
             K8S_AUTH_KUBECONFIG: ~/.kube/customconfig
 
+        - name: Get currently installed version of kubernetes
+          ansible.builtin.command: python -c "import kubernetes; print(kubernetes.__version__)"
+          register: kubernetes_version
+
         - name: Using in-memory kubeconfig should succeed
           kubernetes.core.k8s:
             name: testing
             kind: Namespace
             kubeconfig: "{{ lookup('file', '~/.kube/customconfig') | from_yaml }}"
+          when: kubernetes_version.stdout is version("17.17.0", ">=")
 
       always:
         - name: Return kubeconfig

plugins/module_utils/apply.py

@@ -110,16 +110,17 @@ def apply_object(resource, definition):
     return apply_patch(actual.to_dict(), definition)
 
 
-def k8s_apply(resource, definition):
+def k8s_apply(resource, definition, **kwargs):
     existing, desired = apply_object(resource, definition)
     if not existing:
-        return resource.create(body=desired, namespace=definition['metadata'].get('namespace'))
+        return resource.create(body=desired, namespace=definition['metadata'].get('namespace'), **kwargs)
     if existing == desired:
         return resource.get(name=definition['metadata']['name'], namespace=definition['metadata'].get('namespace'))
     return resource.patch(body=desired,
                           name=definition['metadata']['name'],
                           namespace=definition['metadata'].get('namespace'),
-                          content_type='application/merge-patch+json')
+                          content_type='application/merge-patch+json',
+                          **kwargs)
 
 
 # The patch is the difference from actual to desired without deletions, plus deletions

plugins/module_utils/common.py

@@ -229,6 +229,7 @@ def __init__(self, module, pyyaml_required=True, *args, **kwargs):
             module.fail_json(msg=missing_required_lib('kubernetes'), exception=K8S_IMP_ERR,
                              error=to_native(k8s_import_exception))
         self.kubernetes_version = kubernetes.__version__
+        self.supports_dry_run = LooseVersion(self.kubernetes_version) >= LooseVersion("18.20.0")
 
         if pyyaml_required and not HAS_YAML:
             module.fail_json(msg=missing_required_lib("PyYAML"), exception=YAML_IMP_ERR)
@@ -686,14 +687,18 @@ def _empty_resource_list():
             else:
                 # Delete the object
                 result['changed'] = True
-                if not self.check_mode:
+                if self.check_mode and not self.supports_dry_run:
+                    return result
+                else:
                     if delete_options:
                         body = {
                             'apiVersion': 'v1',
                             'kind': 'DeleteOptions',
                         }
                         body.update(delete_options)
                         params['body'] = body
+                    if self.check_mode:
+                        params['dry_run'] = "All"
                     try:
                         k8s_obj = resource.delete(**params)
                         result['result'] = k8s_obj.to_dict()
@@ -705,7 +710,7 @@ def _empty_resource_list():
                             return result
                         else:
                             self.fail_json(msg=build_error_msg(definition['kind'], origin_name, msg), error=exc.status, status=exc.status, reason=exc.reason)
-                    if wait:
+                    if wait and not self.check_mode:
                         success, resource, duration = self.wait(resource, definition, wait_sleep, wait_timeout, 'absent', label_selectors=label_selectors)
                         result['duration'] = duration
                         if not success:
@@ -726,15 +731,18 @@ def _empty_resource_list():
                                     kind=definition['kind'], name=origin_name, namespace=namespace)
                     return result
             if apply:
-                if self.check_mode:
+                if self.check_mode and not self.supports_dry_run:
                     ignored, patch = apply_object(resource, _encode_stringdata(definition))
                     if existing:
                         k8s_obj = dict_merge(existing.to_dict(), patch)
                     else:
                         k8s_obj = patch
                 else:
                     try:
-                        k8s_obj = resource.apply(definition, namespace=namespace).to_dict()
+                        params = {}
+                        if self.check_mode:
+                            params['dry_run'] = 'All'
+                        k8s_obj = resource.apply(definition, namespace=namespace, **params).to_dict()
                     except DynamicApiError as exc:
                         msg = "Failed to apply object: {0}".format(exc.body)
                         if self.warnings:
@@ -775,11 +783,14 @@ def _empty_resource_list():
                                         parameter has been set to '{state}'".format(
                                         kind=definition['kind'], name=origin_name, state=state)
                     return result
-                elif self.check_mode:
+                elif self.check_mode and not self.supports_dry_run:
                     k8s_obj = _encode_stringdata(definition)
                 else:
+                    params = {}
+                    if self.check_mode:
+                        params['dry_run'] = "All"
                     try:
-                        k8s_obj = resource.create(definition, namespace=namespace).to_dict()
+                        k8s_obj = resource.create(definition, namespace=namespace, **params).to_dict()
                     except ConflictError:
                         # Some resources, like ProjectRequests, can't be created multiple times,
                         # because the resources that they create don't match their kind
@@ -826,11 +837,14 @@ def _empty_resource_list():
             diffs = []
 
             if state == 'present' and existing and force:
-                if self.check_mode:
+                if self.check_mode and not self.supports_dry_run:
                     k8s_obj = _encode_stringdata(definition)
                 else:
+                    params = {}
+                    if self.check_mode:
+                        params['dry_run'] = "All"
                     try:
-                        k8s_obj = resource.replace(definition, name=name, namespace=namespace, append_hash=append_hash).to_dict()
+                        k8s_obj = resource.replace(definition, name=name, namespace=namespace, append_hash=append_hash, **params).to_dict()
                     except DynamicApiError as exc:
                         msg = "Failed to replace object: {0}".format(exc.body)
                         if self.warnings:
@@ -861,7 +875,7 @@ def _empty_resource_list():
                 return result
 
             # Differences exist between the existing obj and requested params
-            if self.check_mode:
+            if self.check_mode and not self.supports_dry_run:
                 k8s_obj = dict_merge(existing.to_dict(), _encode_stringdata(definition))
             else:
                 for merge_type in self.params['merge_type'] or ['strategic-merge', 'merge']:
@@ -903,6 +917,8 @@ def patch_resource(self, resource, definition, existing, name, namespace, merge_
                 version="3.0.0", collection_name="kubernetes.core")
         try:
             params = dict(name=name, namespace=namespace)
+            if self.check_mode:
+                params['dry_run'] = 'All'
             if merge_type:
                 params['content_type'] = 'application/{0}-patch+json'.format(merge_type)
             k8s_obj = resource.patch(definition, **params).to_dict()

plugins/module_utils/k8sdynamicclient.py

@@ -24,7 +24,7 @@
 
 
 class K8SDynamicClient(DynamicClient):
-    def apply(self, resource, body=None, name=None, namespace=None):
+    def apply(self, resource, body=None, name=None, namespace=None, **kwargs):
         body = super().serialize_body(body)
         body['metadata'] = body.get('metadata', dict())
         name = name or body['metadata'].get('name')
@@ -33,7 +33,7 @@ def apply(self, resource, body=None, name=None, namespace=None):
         if resource.namespaced:
             body['metadata']['namespace'] = super().ensure_namespace(resource, namespace, body)
         try:
-            return k8s_apply(resource, body)
+            return k8s_apply(resource, body, **kwargs)
         except ApplyException as e:
             raise ValueError("Could not apply strategic merge to %s/%s: %s" %
                              (body['kind'], body['metadata']['name'], e))

plugins/modules/k8s_json_patch.py

@@ -234,13 +234,16 @@ def build_error_msg(kind, name, msg):
         msg = 'Failed to retrieve requested object: {0}'.format(to_native(exc))
         module.fail_json(msg=build_error_msg(kind, name, msg), error='', status='', reason='')
 
-    if module.check_mode:
+    if module.check_mode and not k8s_module.supports_dry_run:
         obj, error = json_patch(existing.to_dict(), patch)
         if error:
             module.fail_json(**error)
     else:
+        params = {}
+        if module.check_mode:
+            params["dry_run"] = "All"
         try:
-            obj = resource.patch(patch, name=name, namespace=namespace, content_type="application/json-patch+json").to_dict()
+            obj = resource.patch(patch, name=name, namespace=namespace, content_type="application/json-patch+json", **params).to_dict()
         except DynamicApiError as exc:
             msg = "Failed to patch existing object: {0}".format(exc.body)
             module.fail_json(msg=msg, error=exc.status, status=exc.status, reason=exc.reason)