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如何在AWS上建立可水平擴展的EC2群集, 使用AWS CLI



       Auto Scaling on AWS via AWS CLI




前言

以下的文章將帶著大家一步一步的在AWS雲上建立Auto Scaling Group做為可以自動水平擴展的EC2群集, 若文章有有什麼不清楚的地方, 歡迎各位在下方留言, 希望這篇教學能幫助到正在學習AWS的朋友們


大致上需要部屬在雲上的資源有

  • Security Group
  • Launch Configuration
  • Load Balancer
  • Auto Scaling Group


Security Group

Security Group可以決定要開那些Port或是限制那些IP才可以訪問

因為建立Security Group時需要明確指定要建在哪個VPC上, 所以在開始建立Security Group前, 先執行以下的指令把目前可用的VPC Id輸出
vpcId=$(aws ec2 describe-vpcs | jq -r ".Vpcs[0].VpcId")
有了VPC Id後, 接下來才能開始建立Security Group
__sgName='CliGroup123'

sgGroupId=$(aws ec2 create-security-group \
--group-name $__sgName \
--description "My security group" \
--vpc-id  $vpcId | jq -r ".GroupId")
最後做ingress來宣告網路的開口
aws ec2 authorize-security-group-ingress \
    --group-id ${sgGroupId} \
    --protocol tcp \
    --port 5000 \
    --cidr "0.0.0.0/0"

Launch Configuration

Launch Configuration是用來定義VM instance的種類, OS Image的種類以及套哪個Security Group, 使用哪支金鑰對, 網路要不要對外等等的配置資訊
__imgId='ami-0986c2ac728528ac2' 
__lcfgName='my-launch-config10'
__keyName='app123'
__vmType='t2.micro'
#required public ip
aws autoscaling create-launch-configuration \
   --launch-configuration-name ${lcfgName} \
   --key-name $__keyName \
   --security-groups $sgGroupId \
   --instance-type $__vmType \
   --image-id $__imgId \
   --instance-monitoring Enabled=true \
   --no-ebs-optimized \
   --associate-public-ip-address \
   --user-data  "#include https://raw.githubusercontent.com/andy51002000/cloud-formation-example/master/init.sh"

Load Balancer

Load Balancer需要明確定義使用哪個subnet, 為了簡化說明, 這邊拿query到的第一組subnet來用
#https://docs.aws.amazon.com/cli/latest/reference/ec2/describe-subnets.html

subnnetsString = [system.String]::Join(",", $( aws ec2 describe-subnets | jq -r ".Subnets[].SubnetId"))
subnnetsStringList = $( aws ec2 describe-subnets | jq -r ".Subnets[].SubnetId")

建立Load Balancer
#https://docs.aws.amazon.com/zh_tw/elasticloadbalancing/latest/classic/elb-create-internal-load-balancer.html

__lbname="my-internal-loadbalancer4"
aws elb create-load-balancer `
--load-balancer-name $__lbname `
--listeners Protocol=HTTP,LoadBalancerPort=80,InstanceProtocol=HTTP,InstancePort=80 `
--subnets $subnnetsStringList[0] $subnnetsStringList[1] $subnnetsStringList[2]`
--scheme internet-facing `
--security-groups ${sgGroupId}

Load Balancer建立完成後, 還需要新增Listener去監聽指定的port, 以及設定Health Check的規則
aws elb create-load-balancer-listeners \
--load-balancer-name $__lbname \
--listeners Protocol=HTTP,LoadBalancerPort=5000,InstanceProtocol=HTTP,InstancePort=5000
aws elb configure-health-check \
--load-balancer-name $__lbname \
--health-check Target=HTTP:5000/,Interval=30,UnhealthyThreshold=2,HealthyThreshold=2,Timeout=3

Auto Scaling Group

最後建立Auto Scaling Group來部屬以及管理Instance, 我們可以在這邊配置初始的VM數量
__asgname='asg123new222'

aws autoscaling create-auto-scaling-group `
  --auto-scaling-group-name  $__asgname `
  --launch-configuration-name $__lcfgName `
  --min-size 1 `
  --max-size 5 `
  --desired-capacity 1 `
  --vpc-zone-identifier "$subnnetsString"
上面的範例只有配置一個Instance, 若想要增加數量, 可以去調整desired-capacity的參數大小



Ref: https://docs.aws.amazon.com/cli/latest/reference/autoscaling/create-launch-configuration.html https://docs.aws.amazon.com/cli/latest/reference/ec2/create-security-group.html https://docs.aws.amazon.com/cli/latest/userguide/cli-services-ec2-sg.html https://docs.aws.amazon.com/cli/latest/reference/autoscaling/create-auto-scaling-group.html https://docs.aws.amazon.com/zh_tw/elasticloadbalancing/latest/classic/elb-create-internal-load-balancer.html
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