com.netflix.fenzo.AutoScaleRule Maven / Gradle / Ivy

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/*
 * Copyright 2015 Netflix, Inc.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *    http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package com.netflix.fenzo;

/**
 * A rule to define the behavior for auto scaling the number of hosts of a certain type. Rules are defined
 * per unique value of host attribute that is used for matching.
 */
public interface AutoScaleRule {
    /**
     * Value of the host attribute to match to apply this rule.
     * @return Value of matching host attribute.
     */
    public String getRuleName();

    public int getMinIdleHostsToKeep();

    public int getMaxIdleHostsToKeep();

    public long getCoolDownSecs();

    /**
     * Predicate to check if an idle host has too few resources to be considered idle. This is used to filter out hosts
     * with too few resources before considering them as excess resources. If not filtered out, they could prevent a
     * much needed scale up action.
     * @param lease
     * @return
     */
    public boolean idleMachineTooSmall(VirtualMachineLease lease);
}