OpenStack Heat AutoScaling详解及实例代码

2024-09-01 13:49:29

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OpenStack Heat AutoScaling

一、背景

Openstack的Heat是在H版之后加入的组件，旨在创建一套业务流程，更轻松的管理一个集群。集群内的虚拟机可以作为一个整体，统一的为客户提供服务。Heat中把功能定义成资源，在Heat中会用到Nova，Neutron，Ceilometer等组件，这些都可以看成是资源，通过模板文件来描述，模板文件可以是yaml格式，也可以是json格式，一般是yaml格式。
AutoScaling的概念最早出现在AWS，AutoScaling是一项Web服务，目的是根据用户定义的策略，时间表的运行状态检查启动或终止虚拟机，达到自动伸缩。

Openstack里的Auto Scale是由Heat和Ceilometer模块一起配合完成的。Ceilometer负责收集处理性能数据，一旦达到Heat模版里定义的阀值，就发告警信息给heat-engine，由heat-engine调动Heat模版里定义的其它的OpenStack资源实现auto scale。

二、Heat AutoScaling Resources

实现AutoScaling功能涉及到的资源如下：

1.AWS::AutoScaling::AutoScalingGroup

伸缩组是具有相同应用场景的实例的集合，定义了组内实例数的最大值和最小值，冷却时间等等。
注：冷却时间是指一个伸缩活动后的一段锁定时间，在这个时间内不能进行其他的伸缩活动。

语法如下：

{ "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

伸缩配置定义了用于弹性伸缩的实例的配置。由AutoScalingGroup用于配置组内的实例。

语法如下：

{  "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

为auto scale group添加伸缩的策略，定义了具体的扩展或者收缩的操作，以及伸缩的数量。

语法如下：

{  "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还需配合OS::Ceilometer::Alarm使用，由Alarm监控实例的运行状况，一旦超过阈值，则会产生告警。

三、 Heat AutoScaling Template

下面是一个简单的例子:

heat_template_version: 2013-05-23description: Heat template for autoscalingparameters:#定义一些变量 flavor:  type: string  default: m1.small image:  type: string  default: 1a2b3c4f-1a2b-3c4f-5d6e-4130ff5203de availability_zone:  type: string  default: nova alarm_scaleout_threshold:#阈值  type: number  default: 80 alarm_scalein_threshold:#阈值  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中的实例的配置  type: AWS::AutoScaling::LaunchConfiguration  properties:   ImageId: { get_param: image }#实例使用的image   InstanceType: { get_param: flavor }#实例使用的flavor   SecurityGroups: [ get_resource: nova_server_security_group ]   UserData: |#实例启动时运行的脚本     #!/bin/bash     passwd root << EOD     123456     123456     EOD server_group:#伸缩组  type: AWS::AutoScaling::AutoScalingGroup  properties:   AvailabilityZones: []   Cooldown: '60'#冷却时间   LaunchConfigurationName: { get_resource: launch_config }#组中实例的配置   MinSize: '1'#最小实例数   MaxSize: '4'#最大实例数   VPCZoneIdentifier: [ get_resource: neutron_subnet ] scaleout_policy:#向上扩展的策略  type: AWS::AutoScaling::ScalingPolicy  properties:   AdjustmentType: ChangeInCapacity#heat 支持三种调整方式：change_in_capacity (new = current + adjustment), #exact_capacity (new = adjustment), percent_change_in_capacity (在current 的基#础上上按照 adjustment 的 百分比调整)   AutoScalingGroupName: { get_resource: server_group }   ScalingAdjustment: '1'#每次的调整量，即增加一个实例 scalein_policy:#向下收缩的策略  type: AWS::AutoScaling::ScalingPolicy  properties:   AdjustmentType: ChangeInCapacity   AutoScalingGroupName: { get_resource: server_group }   ScalingAdjustment: '-1'#每次的调整量，即减少一个实例 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: #定义一个 ceilometer alarm  type: OS::Ceilometer::Alarm  properties:   description: Scale-up if the average CPU > 80% for 10 minute   meter_name: cpu_util #监控虚拟机的 cpu_util   statistic: avg #statistic 的计算方法为 avg 即平均值法   period: 600 #统计周期   evaluation_periods: 1 #连续几个周期才算有效   repeat_actions: true   threshold: { get_param: alarm_scaleout_threshold }# cpu_util 的阈值   alarm_actions: #该告警在alarm 状态时的 action。    - {get_attr: [scaleout_policy, AlarmUrl]}   matching_metadata: {'metadata.user_metadata.groupname': {get_resource: 'server_group'}}   comparison_operator: gt #检测值和阈值的比较方式为 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#检测值和阈值的比较方式为 lt 即小于outputs: scale_in_url:  value: { get_attr: [ scalein_policy, AlarmUrl ] } scale_out_url:  value: { get_attr: [ scaleout_policy, AlarmUrl ] }

这个stack的功能是监控实例的CPU使用率,当CPU使用率大于80%时,将会启动一个新的实例,当CPU使用率小于20%,将会减少一个实例。

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