Protect users from configuring an ambiguous sensor mode

Author: cognifloyd

templates/deployments.yaml

@@ -1166,7 +1166,10 @@ spec:
 
 {{- $sensor_deployments_count := max 1 ($.Values.st2sensorcontainer.deployments|int) | int }}
 {{- $one_sensor_per_pod := not ($.Values.st2.packs.sensors | empty) }}
-{{- $some_sensors_per_pod := and (not $one_sensor_per_pod) (gt $sensor_deployments_count 1) }}
+{{- $some_sensors_per_pod := gt $sensor_deployments_count 1 }}
+{{- if and $one_sensor_per_pod $some_sensors_per_pod }}
+  {{- fail "The sensor values are ambiguous. To use one-sensor-per-pod, use `st2.packs.sensors`. To use multiple-sensors-per-pod, use `st2sensorcontainer.deployments > 1`. Do not use both!" }}
+{{- end }}
 {{- range ($one_sensor_per_pod | ternary ($.Values.st2.packs.sensors) (until $sensor_deployments_count)) }}
   {{- $sensor := omit $.Values.st2sensorcontainer "name" "ref" "deployments" "postStartScript" }}
   {{- if $one_sensor_per_pod }}

tests/unit/st2sensors_test.yaml

@@ -383,3 +383,18 @@ tests:
       - equal: *multiSensorSecurityContext
         documentIndex: *third_sensor_doc
 
+  - it: ambiguous stackstorm/sensor-mode fails
+    template: deployments.yaml
+    release:
+      name: missing-sensor-ref-release
+    set:
+      st2:
+        packs:
+          sensors:
+            - name: foo
+              ref: some_pack.foo_sensor
+      st2sensorcontainer:
+        deployments: 2
+    asserts:
+      - failedTemplate:
+          errorMessage: "The sensor values are ambiguous. To use one-sensor-per-pod, use `st2.packs.sensors`. To use multiple-sensors-per-pod, use `st2sensorcontainer.deployments > 1`. Do not use both!"

values.yaml

@@ -662,7 +662,7 @@ st2actionrunner:
 # For one-sensor-per-pod, define defaults here and add config for each sensor to st2.packs.sensors (above).
 st2sensorcontainer:
   # "deployments" is analogous to "replicas" for other services. Each deployment has 1 replica.
-  # The deployments count is only used if st2.packs.sensors is empty.
+  # The deployments count cannot be greater than 1 unless st2.packs.sensors is empty.
   # If deployments is 1 (the default), then StackStorm puts all sensors in one pod.
   # If deployments is 2+, StackStorm is configured to use sensor hash ranges to ensure that
   # each sensor runs on only one pod. Each hash range is assigned to a separate