[Terraform] 06 - Autoscaling and ELB

Ref: https://www.udemy.com/course/terraform-cn/learn/lecture/21107132#overview

先创建一个ce2，然后cpu 拉高，触发报警，并创建另一个，分担压力。

 

 

EC2模式

一、关键代码解析

[ autoscaling.tf ]

# 对新增实例的定义
resource "aws_launch_configuration" "example-launchconfig" {
  name_prefix     = "example-launchconfig"
  image_id        = var.AMIS[var.AWS_REGION]
  instance_type   = "t2.micro"
  key_name        = aws_key_pair.mykeypair.key_name
  security_groups = [aws_security_group.allow-ssh.id]
}


resource "aws_autoscaling_group" "example-autoscaling" {
  name                      = "example-autoscaling"
  vpc_zone_identifier       = [aws_subnet.main-public-1.id, aws_subnet.main-public-2.id]
  launch_configuration      = aws_launch_configuration.example-launchconfig.name
  min_size                  = 1
  max_size                  = 2
  health_check_grace_period = 300　　　　# <---- 单位是sec
  health_check_type         = "EC2"
  force_delete              = true

  tag {
    key                 = "Name"
    value               = "ec2 instance"
    propagate_at_launch = true
  }
}

  

[ autoscalingpolicy.tf ]

增容。

# scale up alarm
resource "aws_autoscaling_policy" "example-cpu-policy" {
  name                   = "example-cpu-policy"
  autoscaling_group_name = aws_autoscaling_group.example-autoscaling.name
  adjustment_type        = "ChangeInCapacity"
  scaling_adjustment     = "1"
  cooldown               = "300"
  policy_type            = "SimpleScaling"
}

# 触发警报配置
resource "aws_cloudwatch_metric_alarm" "example-cpu-alarm" {
  alarm_name          = "example-cpu-alarm"
  alarm_description   = "example-cpu-alarm"
  comparison_operator = "GreaterThanOrEqualToThreshold"
  evaluation_periods  = "2"
  metric_name         = "CPUUtilization"
  namespace           = "AWS/EC2"
  period              = "120"
  statistic           = "Average"
  threshold           = "30"

  dimensions = {
    "AutoScalingGroupName" = aws_autoscaling_group.example-autoscaling.name
  }

  actions_enabled = true
  alarm_actions   = [aws_autoscaling_policy.example-cpu-policy.arn]
}

减容。

# scale down alarm
resource "aws_autoscaling_policy" "example-cpu-policy-scaledown" {
  name                   = "example-cpu-policy-scaledown"
  autoscaling_group_name = aws_autoscaling_group.example-autoscaling.name
  adjustment_type        = "ChangeInCapacity"
  scaling_adjustment     = "-1"
  cooldown               = "300"
  policy_type            = "SimpleScaling"
}

# 触发报警配置
resource "aws_cloudwatch_metric_alarm" "example-cpu-alarm-scaledown" {
  alarm_name          = "example-cpu-alarm-scaledown"
  alarm_description   = "example-cpu-alarm-scaledown"
  comparison_operator = "LessThanOrEqualToThreshold"
  evaluation_periods  = "2"
  metric_name         = "CPUUtilization"
  namespace           = "AWS/EC2"
  period              = "120"
  statistic           = "Average"
  threshold           = "5"

  dimensions = {
    "AutoScalingGroupName" = aws_autoscaling_group.example-autoscaling.name
  }

  actions_enabled = true
  alarm_actions   = [aws_autoscaling_policy.example-cpu-policy-scaledown.arn]
}

 

 

二、架构检查

• AUTO SCALING

 

• CloudWatch

Conditions

CPUUtilization >= 30 for 2 datapoints within 4 minutes

CPUUtilization <= 5 for 2 datapoints within 4 minutes

一个scaling up, 一个scaling down。

 

 

三、提高cpu使用率

通过安装stress命令，进行压力测试。

ssh -i mykey ubuntu@<ip address>

(1) Scaling up

自动新创建了一个 instance。

 

(2) 然后自动 scaling down

触发了警报。

自动随机地 terminate 了其中一个 instance。

 

 

 

ELB模式

一、Load Balancer 配置

resource "aws_autoscaling_group" "example-autoscaling" {
  name                      = "example-autoscaling"
  vpc_zone_identifier       = [aws_subnet.main-public-1.id, aws_subnet.main-public-2.id]
  launch_configuration      = aws_launch_configuration.example-launchconfig.name
  min_size                  = 2
  max_size                  = 2
  health_check_grace_period = 300
  health_check_type         = "ELB"
  load_balancers            = [aws_elb.my-elb.name]
  force_delete              = true

  tag {
    key                 = "Name"
    value               = "ec2 instance"
    propagate_at_launch = true
  }
}

• • 生成新实例

resource "aws_launch_configuration" "example-launchconfig" {
  name_prefix     = "example-launchconfig"
  image_id        = var.AMIS[var.AWS_REGION]
  instance_type   = "t2.micro"
  key_name        = aws_key_pair.mykeypair.key_name
  security_groups = [aws_security_group.myinstance.id]

  user_data       = "#!/bin/bash\napt-get update\napt-get -y install net-tools nginx\nMYIP=`ifconfig | grep -E '(inet 10)|(addr:10)' | awk '{ print $2 }' | cut -d ':' -f2`\necho 'this is: '$MYIP > /var/www/html/index.html"
  lifecycle {
    create_before_destroy = true
  }
}

 

• • elb.tf 配置

nginx默认端口80，作为新实例生成的 health检查标准。

resource "aws_elb" "my-elb" {
  name            = "my-elb"
  subnets         = [aws_subnet.main-public-1.id, aws_subnet.main-public-2.id]
  security_groups = [aws_security_group.elb-securitygroup.id]
  listener {
    instance_port     = 80
    instance_protocol = "http"
    lb_port           = 80
    lb_protocol       = "http"
  }
  health_check {
    healthy_threshold   = 2　　　　# 检查的次数，两次都health，才是真health
    unhealthy_threshold = 2
    timeout             = 3
    target              = "HTTP:80/"
    interval            = 30
  }

  cross_zone_load_balancing   = true
  connection_draining         = true
  connection_draining_timeout = 400
  tags = {
    Name = "my-elb"
  }
}

 

 

二、配置结果

耐心等待两个instance的初始化脚本都安装结束。

  

Load Balancer未激活状态？

但结果就是，返回两个vpc子网的其中一个。

 

End.