fix(helm): honor database Pod scheduling constraints

k8s-cluster/ha-cluster/helm_charts/templates/statefulset.yaml

@@ -147,6 +147,18 @@ spec:
         - name: secret
           secret:
             secretName: {{ .Values.clusterName }}
+      {{- with .Values.nodeSelector }}
+      nodeSelector:
+        {{- toYaml . | nindent 8 }}
+      {{- end }}
+      {{- with .Values.affinity }}
+      affinity:
+        {{- toYaml . | nindent 8 }}
+      {{- end }}
+      {{- with .Values.tolerations }}
+      tolerations:
+        {{- toYaml . | nindent 8 }}
+      {{- end }}
       terminationGracePeriodSeconds: 0
   volumeClaimTemplates:
   - metadata:

tests/test_helm_scheduling.py

@@ -0,0 +1,41 @@
+"""Render regression tests. Requires Helm 3 and PyYAML (pip install pyyaml)."""
+import json
+import os
+from pathlib import Path
+import subprocess
+import unittest
+
+CHART = Path(__file__).resolve().parents[1] / 'k8s-cluster/ha-cluster/helm_charts'
+
+def render(overrides=None):
+    command = [os.environ.get('HELM', 'helm'), 'template', 'test', str(CHART)]
+    if overrides:
+        command += ['--values', '-']
+    result = subprocess.run(command, input=json.dumps(overrides or {}),
+                            text=True, encoding='utf-8', capture_output=True, check=True)
+    import yaml
+    return list(yaml.safe_load_all(result.stdout))
+
+def statefulset(documents):
+    return next(doc for doc in documents if doc and doc['kind'] == 'StatefulSet')
+
+class SchedulingTest(unittest.TestCase):
+    def test_defaults_omit_constraints(self):
+        pod = statefulset(render())['spec']['template']['spec']
+        for key in ('nodeSelector', 'affinity', 'tolerations'):
+            self.assertNotIn(key, pod)
+
+    def test_scheduling_constraints(self):
+        settings = {
+            'nodeSelector': {'disktype': 'ssd'},
+            'tolerations': [{'key': 'database', 'operator': 'Equal', 'value': 'ivorysql', 'effect': 'NoSchedule'}],
+            'affinity': {'podAntiAffinity': {'requiredDuringSchedulingIgnoredDuringExecution': [
+                {'labelSelector': {'matchLabels': {'application': 'ivyhac'}},
+                 'topologyKey': 'kubernetes.io/hostname'}]}},
+        }
+        pod = statefulset(render(settings))['spec']['template']['spec']
+        for key, value in settings.items():
+            self.assertEqual(pod.get(key), value, key)
+
+if __name__ == '__main__':
+    unittest.main()