feat(dask): make daskautoscaler optional (reanahub#600)

reana_workflow_controller/config.py

@@ -260,6 +260,9 @@ def _parse_interactive_sessions_environments(env_var):
 DASK_ENABLED = strtobool(os.getenv("DASK_ENABLED", "true"))
 """Whether dask is enabled in the cluster or not"""
 
+DASK_AUTOSCALER_ENABLED = strtobool(os.getenv("DASK_AUTOSCALER_ENABLED", "true"))
+"""Whether dask autoscaler is enabled in the cluster or not"""
+
 REANA_DASK_CLUSTER_DEFAULT_CORES_LIMIT = float(
     os.getenv("REANA_DASK_CLUSTER_DEFAULT_CORES_LIMIT", 4)
 )

reana_workflow_controller/dask.py

@@ -29,6 +29,7 @@
 )
 from reana_commons.job_utils import kubernetes_memory_to_bytes
 
+from reana_workflow_controller.config import DASK_AUTOSCALER_ENABLED
 from reana_workflow_controller.k8s import create_dask_dashboard_ingress
 
 
@@ -62,14 +63,13 @@ def __init__(
         self.memory = memory
         self.single_worker_cores = single_worker_cores
         self.single_worker_memory = single_worker_memory
-        self.autoscaler_name = f"dask-autoscaler-{cluster_name}"
         self.workflow_spec = workflow_spec
         self.workflow_workspace = workflow_workspace
         self.workflow_id = workflow_workspace.split("/")[-1]
         self.user_id = user_id
 
         self.cluster_spec = workflow_spec.get("resources", {}).get("dask", [])
-        self.cluster_body, self.autoscaler_body = self._load_dask_templates()
+        self.cluster_body = self._load_dask_cluster_template()
         self.cluster_image = self.cluster_spec["image"]
         self.dask_scheduler_uri = (
             f"{self.cluster_name}-scheduler.default.svc.cluster.local:8786"
@@ -82,29 +82,43 @@ def __init__(
         )
         self.kubernetes_uid = WORKFLOW_RUNTIME_USER_UID
 
-    def _load_dask_templates(self):
-        """Load Dask templates from YAML files."""
+        if DASK_AUTOSCALER_ENABLED:
+            self.autoscaler_name = f"dask-autoscaler-{cluster_name}"
+            self.autoscaler_body = self._load_dask_autoscaler_template()
+
+    def _load_dask_cluster_template(self):
+        """Load Dask cluster template from YAML file."""
         with open(
             "reana_workflow_controller/templates/dask_cluster.yaml", "r"
-        ) as dask_cluster_yaml, open(
-            "reana_workflow_controller/templates/dask_autoscaler.yaml", "r"
-        ) as dask_autoscaler_yaml:
+        ) as dask_cluster_yaml:
             dask_cluster_body = yaml.safe_load(dask_cluster_yaml)
-            dask_autoscaler_body = yaml.safe_load(dask_autoscaler_yaml)
             dask_cluster_body["spec"]["worker"]["spec"]["initContainers"] = []
             dask_cluster_body["spec"]["worker"]["spec"]["containers"][0]["env"] = []
             dask_cluster_body["spec"]["worker"]["spec"]["containers"][0][
                 "volumeMounts"
             ] = []
             dask_cluster_body["spec"]["worker"]["spec"]["volumes"] = []
 
-            return dask_cluster_body, dask_autoscaler_body
+            return dask_cluster_body
+
+    def _load_dask_autoscaler_template(self):
+        """Load Dask autoscaler template from YAML file."""
+        with open(
+            "reana_workflow_controller/templates/dask_autoscaler.yaml", "r"
+        ) as dask_autoscaler_yaml:
+            dask_autoscaler_body = yaml.safe_load(dask_autoscaler_yaml)
+
+            return dask_autoscaler_body
 
     def create_dask_resources(self):
         """Create necessary dask resources for the workflow."""
         self._prepare_cluster()
         self._create_dask_cluster()
-        self._create_dask_autoscaler()
+
+        if DASK_AUTOSCALER_ENABLED:
+            self._prepare_autoscaler()
+            self._create_dask_autoscaler()
+
         create_dask_dashboard_ingress(self.cluster_name, self.workflow_id)
 
     def _prepare_cluster(self):
@@ -118,16 +132,10 @@ def _prepare_cluster(self):
         # Add the name of the cluster, used in scheduler service name
         self.cluster_body["metadata"] = {"name": self.cluster_name}
 
-        # Add the name of the dask autoscaler
-        self.autoscaler_body["metadata"] = {"name": self.autoscaler_name}
-
         self.cluster_body["spec"]["scheduler"]["service"]["selector"][
             "dask.org/cluster-name"
         ] = self.cluster_name
 
-        # Connect autoscaler to the cluster
-        self.autoscaler_body["spec"]["cluster"] = self.cluster_name
-
         # Add image to worker and scheduler
         self.cluster_body["spec"]["worker"]["spec"]["containers"][0][
             "image"
@@ -149,8 +157,10 @@ def _prepare_cluster(self):
             }
         }
 
-        # Set max limit on autoscaler
-        self.autoscaler_body["spec"]["maximum"] = self.calculate_max_allowed_workers()
+        # Set number of workers in the cluster
+        self.cluster_body["spec"]["worker"]["replicas"] = (
+            0 if DASK_AUTOSCALER_ENABLED else self.calculate_max_allowed_workers()
+        )
 
         # Add DASK SCHEDULER URI env variable
         self.cluster_body["spec"]["worker"]["spec"]["containers"][0]["env"].append(
@@ -182,6 +192,17 @@ def _prepare_cluster(self):
         if rucio:
             self._add_rucio_init_container()
 
+    def _prepare_autoscaler(self):
+        """Prepare Dask autoscaler body."""
+        # Add the name of the dask autoscaler
+        self.autoscaler_body["metadata"] = {"name": self.autoscaler_name}
+
+        # Connect autoscaler to the cluster
+        self.autoscaler_body["spec"]["cluster"] = self.cluster_name
+
+        # Set max limit on autoscaler
+        self.autoscaler_body["spec"]["maximum"] = self.calculate_max_allowed_workers()
+
     def _add_image_pull_secrets(self):
         """Attach the configured image pull secrets to scheduler and worker containers."""
         image_pull_secrets = []

tests/test_dask.py

@@ -441,10 +441,6 @@ def test_prepare_cluster(dask_resource_manager):
             dask_resource_manager.cluster_body["metadata"]["name"]
             == dask_resource_manager.cluster_name
         )
-        assert (
-            dask_resource_manager.autoscaler_body["metadata"]["name"]
-            == dask_resource_manager.autoscaler_name
-        )
 
         assert {
             "name": "DASK_SCHEDULER_URI",
@@ -488,11 +484,6 @@ def test_prepare_cluster(dask_resource_manager):
             "worker"
         ]["spec"]["volumes"]
 
-        assert (
-            dask_resource_manager.autoscaler_body["spec"]["cluster"]
-            == dask_resource_manager.cluster_name
-        )
-
         assert (
             dask_resource_manager.cluster_body["spec"]["scheduler"]["service"][
                 "selector"