Helm: add deployment strategy to chart (#27048)

## Summary & Motivation

Closes: #26445

## How I Tested These Changes

Added test

helm/dagster/charts/dagster-user-deployments/templates/deployment-user.yaml

@@ -14,6 +14,10 @@ metadata:
   annotations: {{ $deployment.annotations | toYaml | nindent 4 }}
 spec:
   replicas: 1
+  {{- if $deployment.deploymentStrategy }}
+  strategy:
+    {{- toYaml $deployment.deploymentStrategy | nindent 4 }}
+  {{- end }}
   selector:
     matchLabels:
       {{- include "dagster.selectorLabels" $ | nindent 6 }}

helm/dagster/charts/dagster-user-deployments/values.yaml

@@ -152,6 +152,10 @@ deployments:
     startupProbe:
       enabled: false
 
+    # Strategy to follow when replacing old pods with new pods. See:
+    # https://kubernetes.io/docs/concepts/workloads/controllers/deployment/#strategy
+    deploymentStrategy: {}
+
     service:
       annotations: {}
 

helm/dagster/schema/schema/charts/dagster_user_deployments/subschema/user_deployments.py

@@ -41,6 +41,7 @@ class UserDeployment(BaseModel):
     schedulerName: Optional[str] = None
     initContainers: Optional[list[kubernetes.Container]] = None
     sidecarContainers: Optional[list[kubernetes.Container]] = None
+    deploymentStrategy: Optional[kubernetes.DeploymentStrategy] = None
 
 
 class UserDeployments(BaseModel):

helm/dagster/schema/schema/charts/utils/kubernetes.py

@@ -194,3 +194,12 @@ class Container(BaseModel):
         "extra": "allow",
         "json_schema_extra": {"$ref": create_definition_ref("io.k8s.api.core.v1.Container")},
     }
+
+
+class DeploymentStrategy(BaseModel):
+    model_config = {
+        "extra": "allow",
+        "json_schema_extra": {
+            "$ref": create_definition_ref("io.k8s.api.apps.v1.DeploymentStrategy")
+        },
+    }

helm/dagster/schema/schema_tests/test_user_deployments.py

@@ -1,6 +1,6 @@
 import json
 import subprocess
-from typing import Union
+from typing import Any, Optional, Union
 
 import pytest
 from dagster_k8s.models import k8s_model_from_dict, k8s_snake_case_dict
@@ -1392,3 +1392,41 @@ def test_old_env(template: HelmTemplate, user_deployment_configmap_template):
 
     [cm] = user_deployment_configmap_template.render(helm_values)
     assert cm.data["test_env"] == "test_value"
+
+
+@pytest.mark.parametrize(
+    "strategy,expected",
+    [
+        (None, None),
+        ({}, None),
+        (
+            {
+                "type": "RollingUpdate",
+                "rollingUpdate": {"maxSurge": 10, "maxUnavailable": 1},
+            },
+            {
+                "type": "RollingUpdate",
+                "rolling_update": {"max_surge": 10, "max_unavailable": 1},
+            },
+        ),
+        (
+            {"type": "Recreate"},
+            {"type": "Recreate", "rolling_update": None},
+        ),
+    ],
+)
+def test_deployment_strategy(
+    template: HelmTemplate,
+    strategy: Optional[dict[str, Any]],
+    expected: Optional[dict[str, Any]],
+):
+    deployment = create_simple_user_deployment("foo")
+    if strategy:
+        deployment.deploymentStrategy = kubernetes.DeploymentStrategy.model_construct(**strategy)
+    helm_values = DagsterHelmValues.construct(
+        dagsterUserDeployments=UserDeployments.model_construct(deployments=[deployment])
+    )
+
+    dagster_user_deployment = template.render(helm_values)
+    assert len(dagster_user_deployment) == 1
+    assert dagster_user_deployment[0].to_dict()["spec"]["strategy"] == expected

helm/dagster/values.yaml

@@ -457,6 +457,10 @@ dagster-user-deployments:
       startupProbe:
         enabled: false
 
+      # Strategy to follow when replacing old pods with new pods. See:
+      # https://kubernetes.io/docs/concepts/workloads/controllers/deployment/#strategy
+      deploymentStrategy: {}
+
       service:
         annotations: {}