Multinode Cleanup (#1360)

* nodecount cleanup

* adds node count to dict marshalling

* updates tests

* updates test

* remove unnecessary things

* pr review

Author: rcano-baseten

truss/base/truss_config.py

@@ -19,6 +19,7 @@
 from truss.base.validation import (
     validate_cpu_spec,
     validate_memory_spec,
+    validate_node_count,
     validate_python_executable_path,
     validate_secret_name,
     validate_secret_to_path_mapping,
@@ -43,7 +44,6 @@
 DEFAULT_CPU = "1"
 DEFAULT_MEMORY = "2Gi"
 DEFAULT_USE_GPU = False
-DEFAULT_NODE_COUNT = 1
 
 DEFAULT_BLOB_BACKEND = HTTP_PUBLIC_BLOB_BACKEND
 
@@ -261,7 +261,7 @@ class Resources:
     memory: str = DEFAULT_MEMORY
     use_gpu: bool = DEFAULT_USE_GPU
     accelerator: AcceleratorSpec = field(default_factory=AcceleratorSpec)
-    node_count: int = DEFAULT_NODE_COUNT
+    node_count: Optional[int] = None
 
     @staticmethod
     def from_dict(d):
@@ -273,24 +273,27 @@ def from_dict(d):
         use_gpu = d.get("use_gpu", DEFAULT_USE_GPU)
         if accelerator.accelerator is not None:
             use_gpu = True
-        # TODO[rcano]: add validation for node count
-        node_count = d.get("node_count", DEFAULT_NODE_COUNT)
-
-        return Resources(
-            cpu=cpu,
-            memory=memory,
-            use_gpu=use_gpu,
-            accelerator=accelerator,
-            node_count=node_count,
-        )
+
+        r = Resources(cpu=cpu, memory=memory, use_gpu=use_gpu, accelerator=accelerator)
+
+        # only add node_count if not None. This helps keep
+        # config generated by truss init concise.
+        node_count = d.get("node_count")
+        validate_node_count(node_count)
+        r.node_count = node_count
+
+        return r
 
     def to_dict(self):
-        return {
+        d = {
             "cpu": self.cpu,
             "memory": self.memory,
             "use_gpu": self.use_gpu,
             "accelerator": self.accelerator.to_str(),
         }
+        if self.node_count is not None:
+            d["node_count"] = self.node_count
+        return d
 
 
 @dataclass
@@ -775,7 +778,7 @@ def _handle_env_vars(env_vars: Dict[str, Any]) -> Dict[str, str]:
 
 
 DATACLASS_TO_REQ_KEYS_MAP = {
-    Resources: {"accelerator", "cpu", "memory", "use_gpu", "node_count"},
+    Resources: {"accelerator", "cpu", "memory", "use_gpu"},
     Runtime: {"predict_concurrency"},
     Build: {"model_server"},
     TrussConfig: {

truss/base/validation.py

@@ -1,7 +1,7 @@
 import math
 import re
 from pathlib import PurePosixPath
-from typing import Dict, Pattern
+from typing import Any, Dict, Pattern
 
 from truss.base.constants import REGISTRY_BUILD_SECRET_PREFIX
 from truss.base.errors import ValidationError
@@ -122,3 +122,17 @@ def validate_python_executable_path(path: str) -> None:
         raise ValidationError(
             f"Invalid relative python executable path {path}. Provide an absolute path"
         )
+
+
+def validate_node_count(node_count: Any) -> None:
+    fieldpath = "resources.node_count"
+    if node_count is None:
+        return None
+    if not isinstance(node_count, int):
+        raise ValidationError(
+            f"{fieldpath} must be a postiive integer. Got {node_count} of type '{type(node_count)}'"
+        )
+    if node_count < 1:
+        raise ValidationError(
+            f"{fieldpath} must be a positive integer. Got {node_count}."
+        )

truss/tests/conftest.py

@@ -731,7 +731,6 @@ def default_config() -> Dict[str, Any]:
             "cpu": "1",
             "memory": "2Gi",
             "use_gpu": False,
-            "node_count": 1,
         },
         "secrets": {},
         "system_packages": [],

truss/tests/test_config.py

@@ -78,6 +78,17 @@
                 "accelerator": "A10G:4",
             },
         ),
+        (
+            {"node_count": 2},
+            Resources(node_count=2),
+            {
+                "cpu": DEFAULT_CPU,
+                "memory": DEFAULT_MEMORY,
+                "use_gpu": False,
+                "accelerator": None,
+                "node_count": 2,
+            },
+        ),
     ],
 )
 def test_parse_resources(input_dict, expect_resources, output_dict):
@@ -170,7 +181,6 @@ def test_default_config_not_crowded_end_to_end():
   accelerator: null
   cpu: '1'
   memory: 2Gi
-  node_count: 1
   use_gpu: false
 secrets: {}
 system_packages: []

truss/tests/test_truss_handle.py

@@ -806,7 +806,6 @@ def generate_default_config():
             "cpu": "1",
             "memory": "2Gi",
             "use_gpu": False,
-            "node_count": 1,
         },
         "secrets": {},
         "system_packages": [],