Add LaunchTemplateOverrides support for compute resources

cli/src/pcluster/aws/ec2.py

@@ -162,6 +162,22 @@ def describe_image(self, ami_id):
             return ImageInfo(images[0])
         raise AWSClientError(function_name="describe_images", message=f"Image {ami_id} not found")
 
+    @AWSExceptionHandler.handle_client_exception
+    @Cache.cached
+    def describe_launch_template_version(self, launch_template_id, version):
+        """Describe a specific launch template version and return its LaunchTemplateData."""
+        response = self._client.describe_launch_template_versions(
+            LaunchTemplateId=launch_template_id,
+            Versions=[str(version)],
+        )
+        versions = response.get("LaunchTemplateVersions", [])
+        if not versions:
+            raise AWSClientError(
+                function_name="describe_launch_template_versions",
+                message=f"Launch template {launch_template_id} version {version} not found",
+            )
+        return versions[0].get("LaunchTemplateData", {})
+
     @AWSExceptionHandler.handle_client_exception
     @Cache.cached
     def describe_images(self, ami_ids, filters, owners):

cli/src/pcluster/config/cluster_config.py

@@ -158,6 +158,7 @@
     InstanceTypePlacementGroupValidator,
     InstanceTypeValidator,
     KeyPairValidator,
+    LaunchTemplateOverridesValidator,
     PlacementGroupCapacityReservationValidator,
     PlacementGroupCapacityTypeValidator,
     PlacementGroupNamingValidator,
@@ -1631,6 +1632,7 @@ def __init__(
         self.managed_head_node_security_group = None
         self.managed_compute_security_group = None
         self.instance_types_data_version = ""
+        self.run_instances_overrides_version = ""
 
     def _register_validators(self, context: ValidatorContext = None):  # noqa: D102 #pylint: disable=unused-argument
         self._register_validator(RegionValidator, region=self.region)
@@ -2222,6 +2224,15 @@ def scheduler_resources(self):
         return str(files(__package__).parent / "resources" / "batch")
 
 
+class LaunchTemplateOverrides(Resource):
+    """Represent the LaunchTemplateOverrides configuration for a compute resource."""
+
+    def __init__(self, launch_template_id: str = None, version: int = None, **kwargs):
+        super().__init__(**kwargs)
+        self.launch_template_id = Resource.init_param(launch_template_id)
+        self.version = Resource.init_param(version)
+
+
 class _BaseSlurmComputeResource(BaseComputeResource):
     """Represent the Slurm Compute Resource."""
 
@@ -2240,6 +2251,7 @@ def __init__(
         tags: List[Tag] = None,
         static_node_priority: int = None,
         dynamic_node_priority: int = None,
+        launch_specification_overrides=None,
         **kwargs,
     ):
         super().__init__(**kwargs)
@@ -2260,6 +2272,7 @@ def __init__(
         self.tags = tags
         self.static_node_priority = Resource.init_param(static_node_priority, default=1)
         self.dynamic_node_priority = Resource.init_param(dynamic_node_priority, default=1000)
+        self.launch_specification_overrides = launch_specification_overrides
 
     @abstractmethod
     def is_flexible(self) -> bool:
@@ -2362,6 +2375,15 @@ def _register_validators(self, context: ValidatorContext = None):
             ec2memory=min_memory,
             instance_type=smallest_type,
         )
+        if self.launch_specification_overrides:
+            self._register_validator(
+                LaunchTemplateOverridesValidator,
+                launch_template_id=self.launch_specification_overrides.launch_template_id,
+                version=self.launch_specification_overrides.version,
+                instance_types=self.instance_types,
+                max_network_cards=self.max_network_cards,
+                is_flexible=self.is_flexible(),
+            )
 
     def is_flexible(self):
         """Return True because the ComputeResource can contain multiple instance types."""
@@ -2449,6 +2471,15 @@ def _register_validators(self, context: ValidatorContext = None):
             ec2memory=self._instance_type_info.ec2memory_size_in_mib(),
             instance_type=self.instance_type,
         )
+        if self.launch_specification_overrides:
+            self._register_validator(
+                LaunchTemplateOverridesValidator,
+                launch_template_id=self.launch_specification_overrides.launch_template_id,
+                version=self.launch_specification_overrides.version,
+                instance_types=self.instance_types,
+                max_network_cards=self.max_network_cards,
+                is_flexible=self.is_flexible(),
+            )
 
     @property
     def architecture(self) -> str:
@@ -2975,6 +3006,40 @@ def get_instance_types_data(self):
                     result[instance_type] = instance_type_info.instance_type_data
         return result
 
+    def get_run_instances_overrides(self):
+        """
+        Build run_instances_overrides data from LaunchTemplateOverrides config.
+
+        Iterates all queues and compute resources. For each compute resource that has
+        launch_specification_overrides configured, fetches the launch template data.
+
+        Returns a dict keyed by {queue_name} -> {compute_resource_name} -> {launch_template_data}.
+        Returns empty dict if no overrides are configured.
+        """
+        overrides = {}
+        for queue in self.scheduling.queues:
+            for compute_resource in queue.compute_resources:
+                if not compute_resource.launch_specification_overrides:
+                    continue
+
+                lt_overrides = compute_resource.launch_specification_overrides
+                lt_id = lt_overrides.launch_template_id
+                lt_version = lt_overrides.version
+
+                LOGGER.info(
+                    "Fetching launch template %s version %s for queue %s, compute resource %s",
+                    lt_id,
+                    lt_version,
+                    queue.name,
+                    compute_resource.name,
+                )
+                lt_data = AWSApi.instance().ec2.describe_launch_template_version(lt_id, lt_version)
+
+                if lt_data:
+                    overrides.setdefault(queue.name, {})[compute_resource.name] = lt_data
+
+        return overrides
+
     @property
     def login_nodes_ami(self):
         """Get the image id of the LoginNodes."""

cli/src/pcluster/constants.py

@@ -232,6 +232,7 @@
     "custom_artifacts_name": "artifacts.zip",
     "scheduler_resources_name": "scheduler_resources.zip",
     "change_set_name": "change-set.json",
+    "run_instances_overrides_name": "run_instances_overrides.json",
 }
 
 PCLUSTER_TAG_VALUE_REGEX = r"^([\w\+\-\=\.\_\:\@/]{0,256})$"

cli/src/pcluster/models/cluster.py

@@ -374,6 +374,7 @@ def create(
             artifact_dir_generated = True
             self._upload_config()
             self._upload_instance_types_data()
+            self._upload_run_instances_overrides()
             LOGGER.info("Generation and upload completed successfully")
 
             # Create template if not provided by the user
@@ -558,6 +559,25 @@ def _upload_instance_types_data(self):
                 e, f"Unable to upload instance types data to the S3 bucket {self.bucket.name} due to exception: {e}"
             )
 
+    def _upload_run_instances_overrides(self):
+        """Upload run_instances_overrides.json to the cluster S3 bucket."""
+        try:
+            overrides = self.config.get_run_instances_overrides()
+            LOGGER.info("Uploading run_instances_overrides.json to S3...")
+            result = self.bucket.upload_config(
+                config=overrides,
+                config_name=PCLUSTER_S3_ARTIFACTS_DICT.get("run_instances_overrides_name"),
+                format=S3FileFormat.JSON,
+            )
+            self.config.run_instances_overrides_version = result.get("VersionId")
+            LOGGER.info("run_instances_overrides.json uploaded successfully.")
+        except Exception as e:
+            raise _cluster_error_mapper(
+                e,
+                f"Unable to upload run_instances_overrides.json to the S3 bucket {self.bucket.name} "
+                f"due to exception: {e}",
+            )
+
     def _upload_change_set(self, changes=None):
         """Upload change set."""
         if changes:
@@ -924,6 +944,7 @@ def update(
             self._add_tags()
             self._upload_config()
             self._upload_instance_types_data()
+            self._upload_run_instances_overrides()
             self._upload_change_set(changes)
 
             # Create template if not provided by the user

cli/src/pcluster/schemas/cluster_schema.py

@@ -64,6 +64,7 @@
     Image,
     Imds,
     IntelSoftware,
+    LaunchTemplateOverrides,
     LocalStorage,
     LoginNodes,
     LoginNodesIam,
@@ -1536,6 +1537,25 @@ def make_resource(self, data, **kwargs):
         return BaseTag(**data)
 
 
+class LaunchTemplateOverridesSchema(BaseSchema):
+    """Represent the schema of the LaunchTemplateOverrides section."""
+
+    launch_template_id = fields.Str(
+        required=True,
+        validate=validate.Regexp(r"^lt-[a-zA-Z0-9]+$"),
+        metadata={"update_policy": UpdatePolicy.QUEUE_UPDATE_STRATEGY},
+    )
+    version = fields.Int(
+        required=True,
+        metadata={"update_policy": UpdatePolicy.QUEUE_UPDATE_STRATEGY},
+    )
+
+    @post_load
+    def make_resource(self, data, **kwargs):
+        """Generate resource."""
+        return LaunchTemplateOverrides(**data)
+
+
 class SlurmComputeResourceSchema(_ComputeResourceSchema):
     """Represent the schema of the Slurm ComputeResource."""
 
@@ -1576,6 +1596,9 @@ class SlurmComputeResourceSchema(_ComputeResourceSchema):
         validate=validate.Range(min=MIN_SLURM_NODE_PRIORITY, max=MAX_SLURM_NODE_PRIORITY),
         metadata={"update_policy": UpdatePolicy.SUPPORTED},
     )
+    launch_specification_overrides = fields.Nested(
+        LaunchTemplateOverridesSchema, metadata={"update_policy": UpdatePolicy.QUEUE_UPDATE_STRATEGY}
+    )
 
     @validates_schema
     def no_coexist_instance_type_flexibility(self, data, **kwargs):

cli/src/pcluster/templates/cluster_stack.py

@@ -1419,10 +1419,13 @@ def _add_head_node(self):
                     ),
                     "cluster_config_version": self.config.config_version,
                     "instance_types_data_version": self.config.instance_types_data_version,
+                    "run_instances_overrides_version": self.config.run_instances_overrides_version,
                     "change_set_s3_key": f"{self.bucket.artifact_directory}/configs/"
                     f"{PCLUSTER_S3_ARTIFACTS_DICT.get('change_set_name')}",
                     "instance_types_data_s3_key": f"{self.bucket.artifact_directory}/configs/"
                     f"{PCLUSTER_S3_ARTIFACTS_DICT.get('instance_types_data_name')}",
+                    "run_instances_overrides_s3_key": f"{self.bucket.artifact_directory}/configs/"
+                    f"{PCLUSTER_S3_ARTIFACTS_DICT.get('run_instances_overrides_name')}",
                     "custom_node_package": self.config.custom_node_package or "",
                     "custom_awsbatchcli_package": self.config.custom_aws_batch_cli_package or "",
                     "head_node_imds_secured": str(self.config.head_node.imds.secured).lower(),

cli/src/pcluster/validators/ec2_validators.py

@@ -870,3 +870,53 @@ def _validate(self, cluster_ultraserver_capacity_block_dict):
                 f"The following capacity blocks have invalid block sizes: {'; '.join(invalid_capacity_blocks)}.",
                 FailureLevel.ERROR,
             )
+
+
+class LaunchTemplateOverridesValidator(Validator):
+    """Validate the launch template overrides configuration."""
+
+    def _validate(self, launch_template_id, version, instance_types, max_network_cards, is_flexible):
+        try:
+            lt_data = AWSApi.instance().ec2.describe_launch_template_version(launch_template_id, str(version))
+        except AWSClientError as e:
+            self._add_failure(
+                f"Unable to retrieve launch template {launch_template_id} version {version}. {str(e)}",
+                FailureLevel.ERROR,
+            )
+            return
+
+        # Check for properties not in allow list
+        allow_list = {"InstanceType", "NetworkInterfaces"}
+        denied_found = [prop for prop in lt_data if prop not in allow_list]
+        if denied_found:
+            self._add_failure(
+                f"Launch template {launch_template_id} contains unsupported properties: "
+                f"{', '.join(sorted(denied_found))}. Only NetworkInterfaces, InstanceType "
+                f"are supported in the override launch template.",
+                FailureLevel.ERROR,
+            )
+
+        # Validate network interface count does not exceed max supported
+        network_interfaces = lt_data.get("NetworkInterfaces", [])
+        if network_interfaces and len(network_interfaces) > max_network_cards:
+            self._add_failure(
+                f"Launch template {launch_template_id} configures {len(network_interfaces)} network interfaces, "
+                f"but the instance type supports a maximum of {max_network_cards}.",
+                FailureLevel.ERROR,
+            )
+
+        # Validate instance type in LT matches the compute resource if specified
+        lt_instance_type = lt_data.get("InstanceType")
+        if lt_instance_type and lt_instance_type not in instance_types:
+            self._add_failure(
+                f"Instance type '{lt_instance_type}' in launch template {launch_template_id} does not match "
+                f"the compute resource instance type(s): {', '.join(instance_types)}.",
+                FailureLevel.ERROR,
+            )
+
+        # Warn if used with flexible instance types
+        if is_flexible:
+            self._add_failure(
+                "LaunchTemplateOverrides cannot be used with flexible instance types.",
+                FailureLevel.ERROR,
+            )

cli/tests/pcluster/example_configs/slurm.full.yaml

@@ -180,6 +180,9 @@ Scheduling:
           HttpProxyAddress: https://proxy-address:port
       ComputeResources:
         - Name: compute-resource-1
+          LaunchTemplateOverrides:
+            LaunchTemplateId: lt-0ab6123b7f1111111
+            Version: "2"
           InstanceType: c4.2xlarge
         - Name: compute-resource-2
           InstanceType: c5.2xlarge