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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