PRcomments

Author: pschoenfelder

SingularityService/src/main/java/com/hubspot/singularity/config/SingularityConfiguration.java

@@ -237,6 +237,8 @@ public class SingularityConfiguration extends Configuration {
 
   private int maxUserIdSize = 100;
 
+  private int maxScaleDownWithoutAcknowledgement = 10;
+
   private boolean storeAllMesosTaskInfoForDebugging = false;
 
   @JsonProperty("historyPurging")
@@ -832,6 +834,10 @@ public int getMaxUserIdSize() {
     return maxUserIdSize;
   }
 
+  public int getMaxScaleDownWithoutAcknowledgement() {
+    return maxScaleDownWithoutAcknowledgement;
+  }
+
   public int getMaxTasksPerOffer() {
     return maxTasksPerOffer;
   }
@@ -1245,6 +1251,12 @@ public void setMaxTasksPerOfferPerRequest(int maxTasksPerOfferPerRequest) {
     this.maxTasksPerOfferPerRequest = maxTasksPerOfferPerRequest;
   }
 
+  public void setMaxScaleDownWithoutAcknowledgement(
+    int maxScaleDownWithoutAcknowledgement
+  ) {
+    this.maxScaleDownWithoutAcknowledgement = maxScaleDownWithoutAcknowledgement;
+  }
+
   public void setMesosConfiguration(MesosConfiguration mesosConfiguration) {
     this.mesosConfiguration = mesosConfiguration;
   }

SingularityService/src/main/java/com/hubspot/singularity/data/SingularityValidator.java

@@ -1241,18 +1241,21 @@ public void checkScale(SingularityRequest request, Optional<Integer> previousSca
     }
 
     if (previousScale.isPresent() && !request.getLargeScaleDownAcknowledged()) {
+      int absMaxScaleDown = singularityConfiguration.getMaxScaleDownWithoutAcknowledgement();
       boolean scaleDownExceedsAbsoluteMax =
-        previousScale.get() - request.getInstancesSafe() > 10;
+        previousScale.get() - request.getInstancesSafe() > absMaxScaleDown;
       boolean scaleDownExceedsRelativeMax =
         request.getInstancesSafe() < (previousScale.get() / 2);
       checkBadRequest(
         !scaleDownExceedsAbsoluteMax,
-        "Cannot scale down by more than %s instances at a time",
-        10
+        "Cannot scale down by more than %s instances at a time without explicit " +
+        "acknowledgement (set the largeScaleDownAcknowledged field in the request)",
+        absMaxScaleDown
       );
       checkBadRequest(
-        !(previousScale.get() > 10 && scaleDownExceedsRelativeMax),
-        "Cannot scale down by more than half of current instances."
+        !(previousScale.get() > absMaxScaleDown && scaleDownExceedsRelativeMax),
+        "Cannot scale down by more than half of current instances without explicit " +
+        "acknowledgement (set the largeScaleDownAcknowledged field in the request)"
       );
     }
   }