OpenStack Heat AutoScaling
一、背景
Openstack的Heat是在H版之后加入的組件，旨在創(chuàng)建一套業(yè)務(wù)流程，更輕松的管理一個集群。集群內(nèi)的虛擬機可以作為一個整體，統(tǒng)一的為客戶提供服務(wù)。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。
AutoScaling的概念最早出現(xiàn)在AWS，AutoScaling是一項Web服務(wù)，目的是根據(jù)用戶定義的策略，時間表的運行狀態(tài)檢查啟動或終止虛擬機，達(dá)到自動伸縮。
Openstack里的Auto Scale是由Heat和Ceilometer模塊一起配合完成的。Ceilometer負(fù)責(zé)收集處理性能數(shù)據(jù)，一旦達(dá)到Heat模版里定義的閥值，就發(fā)告警信息給heat-engine，由heat-engine調(diào)動Heat模版里定義的其它的OpenStack資源實現(xiàn)auto scale。
二、Heat AutoScaling Resources
實現(xiàn)AutoScaling功能涉及到的資源如下：
1.AWS::AutoScaling::AutoScalingGroup
伸縮組是具有相同應(yīng)用場景的實例的集合，定義了組內(nèi)實例數(shù)的最大值和最小值，冷卻時間等等。
注：冷卻時間是指一個伸縮活動后的一段鎖定時間，在這個時間內(nèi)不能進(jìn)行其他的伸縮活動。
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(nèi)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(shù)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, ... ] }} 此外，Heat中AutoScaling還需配合OS::Ceilometer::Alarm使用，由Alarm監(jiān)控實例的運行狀況，一旦超過閾值，則會產(chǎn)生告警。
三、 Heat AutoScaling Template
下面是一個簡單的例子:
heat_template_version: 2013-05-23description: Heat template for autoscalingparameters:#定義一些變量 flavor: type: string default: m1.small image: type: string default: 1a2b3c4f-1a2b-3c4f-5d6e-4130ff5203de availability_zone: type: string default: nova alarm_scaleout_threshold:#閾值 type: number default: 80 alarm_scalein_threshold:#閾值 type: number default: 20resources: neutron_network: type: OS::Neutron::Net properties: name: {get_param: "OS::stack_name"} neutron_subnet: type: OS::Neutron::Subnet properties: name: {get_param: "OS::stack_name"} network_id: { get_resource: neutron_network } cidr: '192.168.111.0/24' gateway_ip: '192.168.111.1' allocation_pools: - start: '192.168.111.2' end: '192.168.111.254' neutron_router: type: OS::Neutron::Router properties: name: {get_param: "OS::stack_name"} add_router_interface: type: OS::Neutron::RouterInterface properties: router_id: { get_resource: neutron_router } subnet_id: { get_resource: neutron_subnet } nova_server_security_group: type: OS::Neutron::SecurityGroup properties: description: 'security group for VM' name: {get_param: "OS::stack_name"} rules: [ {direction: 'ingress', remote_ip_prefix: '0.0.0.0/0', port_range_min: 0, port_range_max: 30000, ethertype: IPv4, protocol: 'tcp'}, {direction: 'egress', remote_ip_prefix: '0.0.0.0/0', port_range_min: 0, port_range_max: 65535, ethertype: 'IPv4', protocol: 'tcp'}, {direction: 'egress', remote_ip_prefix: '0.0.0.0/0', port_range_min: 0, port_range_max: 65535, ethertype: 'IPv4', protocol: 'udp'}, {direction: 'ingress', remote_ip_prefix: '0.0.0.0/0', port_range_min: null, port_range_max: null, ethertype: 'IPv4', protocol: 'icmp'}, {direction: egress, remote_ip_prefix: '0.0.0.0/0', port_range_min: null, port_range_max: null, ethertype: 'IPv4', protocol: 'icmp'} ] launch_config:#Scale group中的實例的配置 type: AWS::AutoScaling::LaunchConfiguration properties: ImageId: { get_param: image }#實例使用的image InstanceType: { get_param: flavor }#實例使用的flavor SecurityGroups: [ get_resource: nova_server_security_group ] UserData: |#實例啟動時運行的腳本 #!/bin/bash passwd root << EOD 123456 123456 EOD server_group:#伸縮組 type: AWS::AutoScaling::AutoScalingGroup properties: AvailabilityZones: [] Cooldown: '60'#冷卻時間 LaunchConfigurationName: { get_resource: launch_config }#組中實例的配置 MinSize: '1'#最小實例數(shù) MaxSize: '4'#最大實例數(shù) VPCZoneIdentifier: [ get_resource: neutron_subnet ] scaleout_policy:#向上擴展的策略 type: AWS::AutoScaling::ScalingPolicy properties: AdjustmentType: ChangeInCapacity#heat 支持三種調(diào)整方式：change_in_capacity (new = current + adjustment), #exact_capacity (new = adjustment), percent_change_in_capacity (在current 的基#礎(chǔ)上上按照 adjustment 的 百分比調(diào)整) AutoScalingGroupName: { get_resource: server_group } ScalingAdjustment: '1'#每次的調(diào)整量，即增加一個實例 scalein_policy:#向下收縮的策略 type: AWS::AutoScaling::ScalingPolicy properties: AdjustmentType: ChangeInCapacity AutoScalingGroupName: { get_resource: server_group } ScalingAdjustment: '-1'#每次的調(diào)整量，即減少一個實例 neutron_port: type: OS::Neutron::Port properties: network_id: { get_resource: neutron_network } fixed_ips: - subnet_id: { get_resource: neutron_subnet } security_groups: [ { get_resource: nova_server_security_group } ] alarm_scaleout: #定義一個 ceilometer alarm type: OS::Ceilometer::Alarm properties: description: Scale-up if the average CPU > 80% for 10 minute meter_name: cpu_util #監(jiān)控虛擬機的 cpu_util statistic: avg #statistic 的計算方法為 avg 即平均值法 period: 600 #統(tǒng)計周期 evaluation_periods: 1 #連續(xù)幾個周期才算有效 repeat_actions: true threshold: { get_param: alarm_scaleout_threshold }# cpu_util 的閾值 alarm_actions: #該告警在alarm 狀態(tài)時的 action。 - {get_attr: [scaleout_policy, AlarmUrl]} matching_metadata: {'metadata.user_metadata.groupname': {get_resource: 'server_group'}} comparison_operator: gt #檢測值和閾值的比較方式為 gt 即大于 alarm_scalein: type: OS::Ceilometer::Alarm properties: description: Scale-down if the average CPU < 20% for 10 minutes meter_name: cpu_util statistic: avg period: 600 evaluation_periods: 1 repeat_actions: true threshold: { get_param: alarm_scalein_threshold } alarm_actions: - {get_attr: [scalein_policy, AlarmUrl]} matching_metadata: {'metadata.user_metadata.groupname': {get_resource: 'server_group'}} comparison_operator: lt#檢測值和閾值的比較方式為 lt 即小于outputs: scale_in_url: value: { get_attr: [ scalein_policy, AlarmUrl ] } scale_out_url: value: { get_attr: [ scaleout_policy, AlarmUrl ] }這個stack的功能是監(jiān)控實例的CPU使用率,當(dāng)CPU使用率大于80%時,將會啟動一個新的實例,當(dāng)CPU使用率小于20%,將會減少一個實例。
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