OpenStack Heat AutoScaling

一、背景

Openstack的Heat是在H版之后加入的組件，旨在創建一套業務流程，更輕松的管理一個集群。集群內的虛擬機可以作為一個整體，統一的為客戶提供服務。Heat中把功能定義成資源，在Heat中會用到Nova，Neutron，Ceilometer等組件，這些都可以看成是資源，通過模板文件來描述，模板文件可以是yaml格式，也可以是json格式，一般是yaml格式。

Openstack里的Auto Scale是由Heat和Ceilometer模塊一起配合完成的。Ceilometer負責收集處理性能數據，一旦達到Heat模版里定義的閥值，就發告警信息給heat-engine，由heat-engine調動Heat模版里定義的其它的OpenStack資源實現auto scale。

二、Heat AutoScaling Resources

實現AutoScaling功能涉及到的資源如下：

1.AWS::AutoScaling::AutoScalingGroup

伸縮組是具有相同應用場景的實例的集合，定義了組內實例數的最大值和最小值，冷卻時間等等。

語法如下：

{ "Type" : "AWS::AutoScaling::AutoScalingGroup", "Properties" : {  "AvailabilityZones" : [ String, ... ],  "Cooldown" : String,  "DesiredCapacity" : String,  "HealthCheckGracePeriod" : Integer,  "HealthCheckType" : String,  "InstanceId" : String,  "LaunchConfigurationName" : String,  "LoadBalancerNames" : [ String, ... ],  "MaxSize" : String,  "MetricsCollection" : [ MetricsCollection, ... ]  "MinSize" : String,  "NotificationConfigurations" : [ NotificationConfigurations, ... ],  "PlacementGroup" : String,  "Tags" : [ Auto Scaling Tag, ..., ],  "TargetGroupARNs" : [ String, ... ],  "TerminationPolicies" : [ String, ..., ],  "VPCZoneIdentifier" : [ String, ... ] }}

2.AWS::AutoScaling::LaunchConfiguration

伸縮配置定義了用于彈性伸縮的實例的配置。由AutoScalingGroup用于配置組內的實例。

語法如下：

{  "Type" : "AWS::AutoScaling::LaunchConfiguration",  "Properties" : {   "AssociatePublicIpAddress" : Boolean,   "BlockDeviceMappings" : [ BlockDeviceMapping, ... ],   "ClassicLinkVPCId" : String,   "ClassicLinkVPCSecurityGroups" : [ String, ... ],   "EbsOptimized" : Boolean,   "IamInstanceProfile" : String,   "ImageId" : String,   "InstanceId" : String,   "InstanceMonitoring" : Boolean,   "InstanceType" : String,   "KernelId" : String,   "KeyName" : String,   "PlacementTenancy" : String,   "RamDiskId" : String,   "SecurityGroups" : [ SecurityGroup, ... ],   "SpotPrice" : String,   "UserData" : String  }}

3.AWS::AutoScaling::ScalingPolicy

為auto scale group添加伸縮的策略，定義了具體的擴展或者收縮的操作，以及伸縮的數量。

語法如下：

{  "Type" : "AWS::AutoScaling::ScalingPolicy",  "Properties" : {   "AdjustmentType" : String,   "AutoScalingGroupName" : String,   "Cooldown" : String,   "EstimatedInstanceWarmup" : Integer,   "MetricAggregationType" : String,   "MinAdjustmentMagnitude" : Integer,   "PolicyType" : String,   "ScalingAdjustment" : Integer,   "StepAdjustments" : [ StepAdjustments, ... ]  }}