add osdisk full cache feature

src/aks-preview/HISTORY.rst

@@ -11,6 +11,7 @@ To release a new version, please select a new version number (usually plus 1 to
 
 Pending
 +++++++
+* `az aks create` and `az aks nodepool add`: Add `--enable-osdisk-full-caching` (preview) to enable the full-cache ephemeral OS disk feature for a node pool. Requires AFEC registration `Microsoft.ContainerService/FullCachePreview`. Property is immutable after node pool creation.
 
 20.0.0b8
 +++++++

src/aks-preview/azext_aks_preview/_help.py

@@ -55,6 +55,14 @@
         - name: --node-osdisk-type
           type: string
           short-summary: OS disk type to be used for machines in a given agent pool. Defaults to 'Ephemeral' when possible in conjunction with VM size and OS disk size. May not be changed for this pool after creation. ('Ephemeral' or 'Managed')
+        - name: --enable-osdisk-fc --enable-osdisk-full-caching
+          type: bool
+          short-summary: Enable the full-cache ephemeral OS disk feature for the default node pool.
+          long-summary: |-
+            When enabled, the entire operating system is cached on the local
+            ephemeral OS disk to mitigate E17 events caused by network failures.
+            Requires Ephemeral OS disk and a VM size with sufficient cache.
+            This property is immutable after the node pool is created.
         - name: --node-osdisk-diskencryptionset-id -d
           type: string
           short-summary: ResourceId of the disk encryption set to use for enabling encryption at rest on agent node os disk.
@@ -2106,6 +2114,14 @@
         - name: --node-osdisk-type
           type: string
           short-summary: OS disk type to be used for machines in a given agent pool. Defaults to 'Ephemeral' when possible in conjunction with VM size and OS disk size. May not be changed for this pool after creation. ('Ephemeral' or 'Managed')
+        - name: --enable-osdisk-fc --enable-osdisk-full-caching
+          type: bool
+          short-summary: Enable the full-cache ephemeral OS disk feature for the node pool.
+          long-summary: |-
+            When enabled, the entire operating system is cached on the local
+            ephemeral OS disk to mitigate E17 events caused by network failures.
+            Requires Ephemeral OS disk and a VM size with sufficient cache.
+            This property is immutable after the node pool is created.
         - name: --max-pods -m
           type: int
           short-summary: The maximum number of pods deployable to a node.

src/aks-preview/azext_aks_preview/_params.py

@@ -240,6 +240,7 @@
     validate_force_upgrade_disable_and_enable_parameters,
     validate_azure_service_mesh_revision,
     validate_artifact_streaming,
+    validate_os_disk_full_caching,
     validate_custom_endpoints,
     validate_bootstrap_container_registry_resource_id,
     validate_gateway_prefix_size,
@@ -899,6 +900,13 @@ def load_arguments(self, _):
         )
         c.argument("node_osdisk_type", arg_type=get_enum_type(node_os_disk_types))
         c.argument("node_osdisk_size", type=int)
+        c.argument(
+            "enable_os_disk_full_caching",
+            options_list=["--enable-osdisk-full-caching", "--enable-osdisk-fc"],
+            action="store_true",
+            validator=validate_os_disk_full_caching,
+            is_preview=True,
+        )
         c.argument("max_pods", type=int, options_list=["--max-pods", "-m"])
         c.argument("vm_set_type", validator=validate_vm_set_type)
         c.argument(
@@ -2067,6 +2075,13 @@ def load_arguments(self, _):
         c.argument("node_taints", validator=validate_nodepool_taints)
         c.argument("node_osdisk_type", arg_type=get_enum_type(node_os_disk_types))
         c.argument("node_osdisk_size", type=int)
+        c.argument(
+            "enable_os_disk_full_caching",
+            options_list=["--enable-osdisk-full-caching", "--enable-osdisk-fc"],
+            action="store_true",
+            validator=validate_os_disk_full_caching,
+            is_preview=True,
+        )
         # upgrade strategy
         c.argument("upgrade_strategy", arg_type=get_enum_type(upgrade_strategies))
         # rolling upgrade params

src/aks-preview/azext_aks_preview/_validators.py

@@ -21,7 +21,8 @@
     CONST_MANAGED_CLUSTER_SKU_TIER_STANDARD,
     CONST_NETWORK_POD_IP_ALLOCATION_MODE_DYNAMIC_INDIVIDUAL,
     CONST_NETWORK_POD_IP_ALLOCATION_MODE_STATIC_BLOCK,
-    CONST_NODEPOOL_MODE_GATEWAY, CONST_OS_SKU_AZURELINUX,
+    CONST_NODEPOOL_MODE_GATEWAY, CONST_OS_DISK_TYPE_MANAGED,
+    CONST_OS_SKU_AZURELINUX,
     CONST_OS_SKU_CBLMARINER, CONST_OS_SKU_MARINER)
 from azext_aks_preview._helpers import _fuzzy_match
 from azure.cli.core import keys
@@ -953,6 +954,22 @@ def validate_asm_egress_name(namespace):
         )
 
 
+def validate_os_disk_full_caching(namespace):
+    """Reject --enable-osdisk-full-caching when OS disk type is explicitly Managed.
+
+    Full-cache OS disk requires Ephemeral storage; failing fast at the CLI gives
+    a clearer error than waiting for an ARM round-trip.
+    """
+    if not getattr(namespace, "enable_os_disk_full_caching", False):
+        return
+    node_osdisk_type = getattr(namespace, "node_osdisk_type", None)
+    if node_osdisk_type == CONST_OS_DISK_TYPE_MANAGED:
+        raise ArgumentUsageError(
+            "--enable-osdisk-full-caching requires Ephemeral OS disk; "
+            "it cannot be used with --node-osdisk-type Managed."
+        )
+
+
 def validate_artifact_streaming(namespace):
     """Validates artifact streaming flags for mutual exclusivity and OS support."""
     enable_artifact_streaming = getattr(namespace, "enable_artifact_streaming", False)

src/aks-preview/azext_aks_preview/agentpool_decorator.py

@@ -606,6 +606,19 @@ def get_enable_artifact_streaming(self) -> bool:
             )
         return enable_artifact_streaming
 
+    def get_enable_os_disk_full_caching(self) -> bool:
+        """Obtain the value of enable_os_disk_full_caching.
+        :return: bool
+        """
+        enable_os_disk_full_caching = self.raw_param.get("enable_os_disk_full_caching")
+        if self.decorator_mode == DecoratorMode.CREATE:
+            if (
+                self.agentpool and
+                self.agentpool.enable_os_disk_full_caching is not None
+            ):
+                enable_os_disk_full_caching = self.agentpool.enable_os_disk_full_caching
+        return enable_os_disk_full_caching
+
     def get_enable_managed_gpu(self) -> Union[bool, None]:
         """Obtain the value of enable_managed_gpu.
         :return: bool
@@ -1327,6 +1340,14 @@ def set_up_artifact_streaming(self, agentpool: AgentPool) -> AgentPool:
             agentpool.artifact_streaming_profile.enabled = True
         return agentpool
 
+    def set_up_os_disk_full_caching(self, agentpool: AgentPool) -> AgentPool:
+        """Set up enable_os_disk_full_caching property for the AgentPool object."""
+        self._ensure_agentpool(agentpool)
+
+        if self.context.get_enable_os_disk_full_caching():
+            agentpool.enable_os_disk_full_caching = True
+        return agentpool
+
     def set_up_managed_gpu(self, agentpool: AgentPool) -> AgentPool:
         """Set up managed GPU property for the AgentPool object."""
         self._ensure_agentpool(agentpool)
@@ -1606,6 +1627,8 @@ def construct_agentpool_profile_preview(self) -> AgentPool:
         agentpool = self.set_up_init_taints(agentpool)
         # set up artifact streaming
         agentpool = self.set_up_artifact_streaming(agentpool)
+        # set up os disk full caching
+        agentpool = self.set_up_os_disk_full_caching(agentpool)
         # set up managed gpu
         agentpool = self.set_up_managed_gpu(agentpool)
         # set up skip_gpu_driver_install

src/aks-preview/azext_aks_preview/custom.py

@@ -1066,6 +1066,7 @@ def aks_create(
     nodepool_initialization_taints=None,
     node_osdisk_type=None,
     node_osdisk_size=0,
+    enable_os_disk_full_caching=False,
     vm_set_type=None,
     zones=None,
     ppg=None,
@@ -1936,6 +1937,7 @@ def aks_agentpool_add(
     node_taints=None,
     node_osdisk_type=None,
     node_osdisk_size=0,
+    enable_os_disk_full_caching=False,
     max_surge=None,
     drain_timeout=None,
     node_soak_duration=None,

src/aks-preview/azext_aks_preview/tests/latest/test_agentpool_decorator.py

@@ -258,6 +258,61 @@ def common_get_enable_artifact_streaming(self):
         ctx_2.attach_agentpool(agentpool_2)
         self.assertEqual(ctx_2.get_enable_artifact_streaming(), None)
 
+    def common_get_enable_os_disk_full_caching(self):
+        # default: store_true flag not provided -> raw is False
+        ctx_1 = AKSPreviewAgentPoolContext(
+            self.cmd,
+            AKSAgentPoolParamDict({"enable_os_disk_full_caching": False}),
+            self.models,
+            DecoratorMode.CREATE,
+            self.agentpool_decorator_mode,
+        )
+        self.assertEqual(ctx_1.get_enable_os_disk_full_caching(), False)
+        # CREATE: value on attached agentpool overrides default False
+        agentpool_1 = self.create_initialized_agentpool_instance(
+            enable_os_disk_full_caching=True
+        )
+        ctx_1.attach_agentpool(agentpool_1)
+        self.assertEqual(ctx_1.get_enable_os_disk_full_caching(), True)
+
+        # explicit True from raw param, no attached agentpool
+        ctx_2 = AKSPreviewAgentPoolContext(
+            self.cmd,
+            AKSAgentPoolParamDict({"enable_os_disk_full_caching": True}),
+            self.models,
+            DecoratorMode.CREATE,
+            self.agentpool_decorator_mode,
+        )
+        self.assertEqual(ctx_2.get_enable_os_disk_full_caching(), True)
+
+        # priority: raw True is overridden by attached agentpool False in CREATE mode
+        ctx_3 = AKSPreviewAgentPoolContext(
+            self.cmd,
+            AKSAgentPoolParamDict({"enable_os_disk_full_caching": True}),
+            self.models,
+            DecoratorMode.CREATE,
+            self.agentpool_decorator_mode,
+        )
+        agentpool_3 = self.create_initialized_agentpool_instance(
+            enable_os_disk_full_caching=False
+        )
+        ctx_3.attach_agentpool(agentpool_3)
+        self.assertEqual(ctx_3.get_enable_os_disk_full_caching(), False)
+
+        # UPDATE mode gate: attached agentpool MUST NOT override raw_param
+        ctx_4 = AKSPreviewAgentPoolContext(
+            self.cmd,
+            AKSAgentPoolParamDict({"enable_os_disk_full_caching": False}),
+            self.models,
+            DecoratorMode.UPDATE,
+            self.agentpool_decorator_mode,
+        )
+        agentpool_4 = self.create_initialized_agentpool_instance(
+            enable_os_disk_full_caching=True
+        )
+        ctx_4.attach_agentpool(agentpool_4)
+        self.assertEqual(ctx_4.get_enable_os_disk_full_caching(), False)
+
     def common_get_disable_artifact_streaming(self):
         # default
         ctx_1 = AKSPreviewAgentPoolContext(
@@ -1155,6 +1210,9 @@ def test_get_workload_runtime(self):
     def test_get_enable_artifact_streaming(self):
         self.common_get_enable_artifact_streaming()
 
+    def test_get_enable_os_disk_full_caching(self):
+        self.common_get_enable_os_disk_full_caching()
+
     def test_get_disable_artifact_streaming(self):
         self.common_get_disable_artifact_streaming()
 
@@ -1257,7 +1315,10 @@ def test_get_workload_runtime(self):
 
     def test_get_enable_artifact_streaming(self):
         self.common_get_enable_artifact_streaming()
-
+
+    def test_get_enable_os_disk_full_caching(self):
+        self.common_get_enable_os_disk_full_caching()
+
     def test_get_enable_managed_gpu(self):
         self.common_get_enable_managed_gpu()
 
@@ -1583,6 +1644,41 @@ def common_set_up_artifact_streaming(self):
         )
         self.assertEqual(dec_agentpool_1, ground_truth_agentpool_1)
 
+    def common_set_up_os_disk_full_caching(self):
+        # default: store_true flag not provided -> raw is False -> field stays unset
+        dec_default = AKSPreviewAgentPoolAddDecorator(
+            self.cmd,
+            self.client,
+            {"enable_os_disk_full_caching": False},
+            self.resource_type,
+            self.agentpool_decorator_mode,
+        )
+        with self.assertRaises(CLIInternalError):
+            dec_default.set_up_os_disk_full_caching(None)
+        agentpool_default = self.create_initialized_agentpool_instance(restore_defaults=False)
+        dec_default.context.attach_agentpool(agentpool_default)
+        dec_agentpool_default = dec_default.set_up_os_disk_full_caching(agentpool_default)
+        dec_agentpool_default = self._restore_defaults_in_agentpool(dec_agentpool_default)
+        ground_truth_default = self.create_initialized_agentpool_instance()
+        self.assertEqual(dec_agentpool_default, ground_truth_default)
+
+        # explicit True -> field set to True
+        dec_true = AKSPreviewAgentPoolAddDecorator(
+            self.cmd,
+            self.client,
+            {"enable_os_disk_full_caching": True},
+            self.resource_type,
+            self.agentpool_decorator_mode,
+        )
+        agentpool_true = self.create_initialized_agentpool_instance(restore_defaults=False)
+        dec_true.context.attach_agentpool(agentpool_true)
+        dec_agentpool_true = dec_true.set_up_os_disk_full_caching(agentpool_true)
+        dec_agentpool_true = self._restore_defaults_in_agentpool(dec_agentpool_true)
+        ground_truth_true = self.create_initialized_agentpool_instance(
+            enable_os_disk_full_caching=True
+        )
+        self.assertEqual(dec_agentpool_true, ground_truth_true)
+
     def common_set_up_managed_gpu(self):
         dec_1 = AKSPreviewAgentPoolAddDecorator(
             self.cmd,
@@ -2157,6 +2253,9 @@ def test_set_up_gpu_propertes(self):
     def test_set_up_artifact_streaming(self):
         self.common_set_up_artifact_streaming()
 
+    def test_set_up_os_disk_full_caching(self):
+        self.common_set_up_os_disk_full_caching()
+
     def test_set_up_managed_gpu(self):
         self.common_set_up_managed_gpu()
 
@@ -2305,7 +2404,10 @@ def test_set_up_gpu_propertes(self):
 
     def test_set_up_artifact_streaming(self):
         self.common_set_up_artifact_streaming()
-
+
+    def test_set_up_os_disk_full_caching(self):
+        self.common_set_up_os_disk_full_caching()
+
     def test_set_up_managed_gpu(self):
         self.common_set_up_managed_gpu()