enable using ephemeral disks by default (#461)

docs/webhook_events.md

@@ -800,6 +800,11 @@ Each event will be submitted via HTTP POST to the user provided URL.
         },
         "AutoScaleConfig": {
             "properties": {
+                "ephemeral_os_disks": {
+                    "default": false,
+                    "title": "Ephemeral Os Disks",
+                    "type": "boolean"
+                },
                 "image": {
                     "title": "Image",
                     "type": "string"
@@ -3764,6 +3769,11 @@ Each event will be submitted via HTTP POST to the user provided URL.
         },
         "AutoScaleConfig": {
             "properties": {
+                "ephemeral_os_disks": {
+                    "default": false,
+                    "title": "Ephemeral Os Disks",
+                    "type": "boolean"
+                },
                 "image": {
                     "title": "Image",
                     "type": "string"

src/api-service/__app__/onefuzzlib/autoscale.py

@@ -75,6 +75,7 @@ def scale_up(pool: Pool, scalesets: List[Scaleset], nodes_needed: int) -> None:
             region=autoscale_config.region,
             size=max_nodes_scaleset,
             spot_instances=autoscale_config.spot_instances,
+            ephemeral_os_disks=autoscale_config.ephemeral_os_disks,
             tags={"pool": pool.name},
         )
         nodes_needed -= max_nodes_scaleset

src/api-service/__app__/onefuzzlib/azure/vmss.py

@@ -208,6 +208,7 @@ def create_vmss(
     image: str,
     network_id: str,
     spot_instances: bool,
+    ephemeral_os_disks: bool,
     extensions: List[Any],
     password: str,
     ssh_public_key: str,
@@ -259,7 +260,9 @@ def create_vmss(
         },
         "virtual_machine_profile": {
             "priority": "Regular",
-            "storage_profile": {"image_reference": image_ref},
+            "storage_profile": {
+                "image_reference": image_ref,
+            },
             "os_profile": {
                 "computer_name_prefix": "node",
                 "admin_username": "onefuzz",
@@ -300,6 +303,13 @@ def create_vmss(
             },
         }
 
+    if ephemeral_os_disks:
+        params["virtual_machine_profile"]["storage_profile"]["os_disk"] = {
+            "diffDiskSettings": {"option": "Local"},
+            "caching": "ReadOnly",
+            "createOption": "FromImage",
+        }
+
     if spot_instances:
         # Setting max price to -1 means it won't be evicted because of
         # price.

src/api-service/__app__/onefuzzlib/workers/scalesets.py

@@ -82,6 +82,7 @@ class Scaleset(BASE_SCALESET, ORMMixin):
         region: Region,
         size: int,
         spot_instances: bool,
+        ephemeral_os_disks: bool,
         tags: Dict[str, str],
         client_id: Optional[UUID] = None,
         client_object_id: Optional[UUID] = None,
@@ -93,6 +94,7 @@ class Scaleset(BASE_SCALESET, ORMMixin):
             region=region,
             size=size,
             spot_instances=spot_instances,
+            ephemeral_os_disks=ephemeral_os_disks,
             auth=build_auth(),
             client_id=client_id,
             client_object_id=client_object_id,
@@ -237,6 +239,7 @@ class Scaleset(BASE_SCALESET, ORMMixin):
                 self.image,
                 network_id,
                 self.spot_instances,
+                self.ephemeral_os_disks,
                 extensions,
                 self.auth.password,
                 self.auth.public_key,

src/api-service/__app__/scaleset/__init__.py

@@ -92,6 +92,7 @@ def post(req: func.HttpRequest) -> func.HttpResponse:
         region=region,
         size=request.size,
         spot_instances=request.spot_instances,
+        ephemeral_os_disks=request.ephemeral_os_disks,
         tags=request.tags,
     )
     # don't return auths during create, only 'get' with include_auth

src/cli/onefuzz/api.py

@@ -1279,6 +1279,7 @@ class Scaleset(Endpoint):
         vm_sku: Optional[str] = "Standard_D2s_v3",
         region: Optional[primitives.Region] = None,
         spot_instances: bool = False,
+        ephemeral_os_disks: bool = True,
         tags: Optional[Dict[str, str]] = None,
     ) -> models.Scaleset:
         self.logger.debug("create scaleset")
@@ -1305,6 +1306,7 @@ class Scaleset(Endpoint):
                 region=region,
                 size=size,
                 spot_instances=spot_instances,
+                ephemeral_os_disks=ephemeral_os_disks,
                 tags=tags,
             ),
         )

src/pytypes/onefuzztypes/models.py

@@ -586,6 +586,7 @@ class AutoScaleConfig(BaseModel):
     region: Optional[Region]
     scaleset_size: int  # Individual scaleset size
     spot_instances: bool = Field(default=False)
+    ephemeral_os_disks: bool = Field(default=False)
     vm_sku: str
 
     @validator("scaleset_size", allow_reuse=True)
@@ -654,6 +655,7 @@ class Scaleset(BaseModel):
     region: Region
     size: int
     spot_instances: bool
+    ephemeral_os_disks: bool = Field(default=False)
     needs_config_update: bool = Field(default=False)
     error: Optional[Error]
     nodes: Optional[List[ScalesetNodeState]]

src/pytypes/onefuzztypes/requests.py

@@ -176,6 +176,7 @@ class ScalesetCreate(BaseRequest):
     region: Optional[Region]
     size: int
     spot_instances: bool
+    ephemeral_os_disks: bool
     tags: Dict[str, str]
 
     @validator("size", allow_reuse=True)