AWS 的解决方案：
- 弹性负载均衡器（ELB），用于同步解耦。
- Application Load Balancer；
- 网络负载均衡器；
- Classic Load Balancer；
- 消息队列服务（SQS），用于异步解耦。
一、利用负载均衡器实现同步解耦
实现将流量与 Web 服务器解耦。
负载均衡器同步解耦服务器
- 负载均衡器将传入的请求路由到两个后端的Web服务器之一；
- 负载均衡器可以通过 DNS 从互联网访问；
- Web 服务器只能通过负载均衡器访问；
CloudFormation 示例模版代码：
{
"AWSTemplateFormatVersion": "2010-09-09",
"Description": "AWS in Action: chapter 12 (Load Balancer)",
"Parameters": {
"KeyName": {
"Description": "Key Pair name",
"Type": "AWS::EC2::KeyPair::KeyName",
"Default": "mykey"
},
"NumberOfServers": {
"Description": "Number of servers",
"Type": "Number",
"Default": "2",
"MinValue": "2",
"MaxValue": "4"
}
},
"Mappings": {
"EC2RegionMap": {
"ap-northeast-1": {"AmazonLinuxAMIHVMEBSBacked64bit": "ami-cbf90ecb"},
"ap-southeast-1": {"AmazonLinuxAMIHVMEBSBacked64bit": "ami-68d8e93a"},
"ap-southeast-2": {"AmazonLinuxAMIHVMEBSBacked64bit": "ami-fd9cecc7"},
"eu-central-1": {"AmazonLinuxAMIHVMEBSBacked64bit": "ami-a8221fb5"},
"eu-west-1": {"AmazonLinuxAMIHVMEBSBacked64bit": "ami-a10897d6"},
"sa-east-1": {"AmazonLinuxAMIHVMEBSBacked64bit": "ami-b52890a8"},
"us-east-1": {"AmazonLinuxAMIHVMEBSBacked64bit": "ami-1ecae776"},
"us-west-1": {"AmazonLinuxAMIHVMEBSBacked64bit": "ami-d114f295"},
"us-west-2": {"AmazonLinuxAMIHVMEBSBacked64bit": "ami-e7527ed7"}
}
},
"Resources": {
"VPC": {
"Type": "AWS::EC2::VPC",
"Properties": {
"CidrBlock": "172.31.0.0/16",
"EnableDnsHostnames": "true"
}
},
"InternetGateway": {
"Type": "AWS::EC2::InternetGateway",
"Properties": {
}
},
"VPCGatewayAttachment": {
"Type": "AWS::EC2::VPCGatewayAttachment",
"Properties": {
"VpcId": {"Ref": "VPC"},
"InternetGatewayId": {"Ref": "InternetGateway"}
}
},
"Subnet": {
"Type": "AWS::EC2::Subnet",
"Properties": {
"AvailabilityZone": {"Fn::Select": ["0", {"Fn::GetAZs": ""}]},
"CidrBlock": "172.31.38.0/24",
"VpcId": {"Ref": "VPC"}
}
},
"RouteTable": {
"Type": "AWS::EC2::RouteTable",
"Properties": {
"VpcId": {"Ref": "VPC"}
}
},
"RouteTableAssociation": {
"Type": "AWS::EC2::SubnetRouteTableAssociation",
"Properties": {
"SubnetId": {"Ref": "Subnet"},
"RouteTableId": {"Ref": "RouteTable"}
}
},
"RoutePublicNATToInternet": {
"Type": "AWS::EC2::Route",
"Properties": {
"RouteTableId": {"Ref": "RouteTable"},
"DestinationCidrBlock": "0.0.0.0/0",
"GatewayId": {"Ref": "InternetGateway"}
},
"DependsOn": "VPCGatewayAttachment"
},
"NetworkAcl": {
"Type": "AWS::EC2::NetworkAcl",
"Properties": {
"VpcId": {"Ref": "VPC"}
}
},
"SubnetNetworkAclAssociation": {
"Type": "AWS::EC2::SubnetNetworkAclAssociation",
"Properties": {
"SubnetId": {"Ref": "Subnet"},
"NetworkAclId": {"Ref": "NetworkAcl"}
}
},
"NetworkAclEntryIngress": {
"Type": "AWS::EC2::NetworkAclEntry",
"Properties": {
"NetworkAclId": {"Ref": "NetworkAcl"},
"RuleNumber": "100",
"Protocol": "-1",
"RuleAction": "allow",
"Egress": "false",
"CidrBlock": "0.0.0.0/0"
}
},
"NetworkAclEntryEgress": {
"Type": "AWS::EC2::NetworkAclEntry",
"Properties": {
"NetworkAclId": {"Ref": "NetworkAcl"},
"RuleNumber": "100",
"Protocol": "-1",
"RuleAction": "allow",
"Egress": "true",
"CidrBlock": "0.0.0.0/0"
}
},
"LoadBalancerSecurityGroup": { # 负载均衡器安全组设置
"Type": "AWS::EC2::SecurityGroup",
"Properties": {
"GroupDescription": "elb-sg",
"VpcId": {"Ref": "VPC"},
"SecurityGroupIngress": [{
"CidrIp": "0.0.0.0/0",
"FromPort": 80, # 负载均衡器只接受 80 端口的流量
"IpProtocol": "tcp",
"ToPort": 80
}]
}
},
"LoadBalancer": {
"Type": "AWS::ElasticLoadBalancing::LoadBalancer",
"Properties": {
"Subnets": [{"Ref": "Subnet"}], # 将 ELB 附加到子网上
"LoadBalancerName": "elb",
"Listeners": [{ # 映射负载均衡器的端口到其后端的服务器端口
"InstancePort": "80",
"InstanceProtocol": "HTTP",
"LoadBalancerPort": "80",
"Protocol": "HTTP"
}],
"HealthCheck": { # ELB 健康状态检查
"Target": "HTTP:80/index.html", # 检查对/index.html 返回的状态码是否为 200
"Interval": "10", # 每 10s 进行一次检查
"Timeout": "5", # 超时时间为 5s
"UnhealthyThreshold": "2", # 检查连续失败2次，则认为是运行状况不好的
"HealthyThreshold": "3", # 检查连续通过 3 次才能认为是运行状况良好的
},
"SecurityGroups": [{"Ref": "LoadBalancerSecurityGroup"}], # 关联安全组
"Scheme": "internet-facing" # 设置为公开可访问
},
"DependsOn": "VPCGatewayAttachment"
},
"WebServerSecurityGroup": {
"Type": "AWS::EC2::SecurityGroup",
"Properties": {
"GroupDescription": "awsinaction-sg",
"VpcId": {"Ref": "VPC"},
"SecurityGroupIngress": [{
"CidrIp": "0.0.0.0/0",
"FromPort": 22,
"IpProtocol": "tcp",
"ToPort": 22
}, {
"FromPort": 80,
"IpProtocol": "tcp",
"SourceSecurityGroupId": {"Ref": "LoadBalancerSecurityGroup"},
"ToPort": 80
}]
}
},
"LaunchConfiguration": {
"Type": "AWS::AutoScaling::LaunchConfiguration",
"Metadata": {
"AWS::CloudFormation::Init": {
"config": {
"packages": {
"yum": {
"httpd": []
}
},
"files": {
"/tmp/config": {
"content": {"Fn::Join": ["", [
"#!/bin/bash -ex\n",
"PRIVATE_IP=`curl -s http://169.254.169.254/latest/meta-data/local-ipv4`\n",
"echo \"$PRIVATE_IP $PRIVATE_IP
\" > index.html\n"
]]},
"mode": "000500",
"owner": "root",
"group": "root"
}
},
"commands": {
"01_config": {
"command": "/tmp/config",
"cwd": "/var/www/html"
}
},
"services": {
"sysvinit": {
"httpd": {
"enabled": "true",
"ensureRunning": "true"
}
}
}
}
}
},
"Properties": {
"EbsOptimized": false,
"ImageId": {"Fn::FindInMap": ["EC2RegionMap", {"Ref": "AWS::Region"}, "AmazonLinuxAMIHVMEBSBacked64bit"]},
"InstanceType": "t2.micro",
"SecurityGroups": [{"Ref": "WebServerSecurityGroup"}],
"KeyName": {"Ref": "KeyName"},
"AssociatePublicIpAddress": true,
"UserData": {"Fn::Base64": {"Fn::Join": ["", [
"#!/bin/bash -ex\n",
"yum update -y aws-cfn-bootstrap\n",
"/opt/aws/bin/cfn-init -v --stack ", {"Ref": "AWS::StackName"}, " --resource LaunchConfiguration --region ", {"Ref": "AWS::Region"}, "\n",
"/opt/aws/bin/cfn-signal -e $? --stack ", {"Ref": "AWS::StackName"}, " --resource AutoScalingGroup --region ", {"Ref": "AWS::Region"}, "\n"
]]}}
}
},
"AutoScalingGroup": { # 自动扩展
"Type": "AWS::AutoScaling::AutoScalingGroup",
"Properties": {
"LoadBalancerNames": [{"Ref": "LoadBalancer"}], # 将自动扩展组连接到 ELB
"LaunchConfigurationName": {"Ref": "LaunchConfiguration"},
"MinSize": {"Ref": "NumberOfServers"}, # 最小尺寸
"MaxSize": {"Ref": "NumberOfServers"}, # 最大尺寸
"DesiredCapacity": {"Ref": "NumberOfServers"}, # 容量
"VPCZoneIdentifier": [{"Ref": "Subnet"}]
},
"CreationPolicy": {
"ResourceSignal": {
"Timeout": "PT10M"
}
},
"DependsOn": "VPCGatewayAttachment"
}
},
"Outputs": {
"URL": {
"Value": {"Fn::Join": ["", ["http://", {"Fn::GetAtt": ["LoadBalancer", "DNSName"]}]]},
"Description": "Load Balancer URL"
}
}
}
更多使用场景
- 处理 TCP 流量；
- ELB 支持 SSL 证书。
- 记录日志，并将日志存储到 S3 上。
- 跨可用区的负载均衡。（建议启用跨可用区负载均衡，默认情况下是禁用的）。
二、利用消息队列实现异步解耦
Amazon Simple Queue Service
适用于微服务、分布式系统和无服务器应用程序的完全托管的消息队列
Amazon Simple Queue Service (SQS) 是一种完全托管的消息队列服务，可让您分离和扩展微服务、分布式系统和无服务器应用程序。SQS 消除了与管理和运营消息型中间件相关的复杂性和开销，并使开发人员能够专注于重要工作。借助 SQS，您可以在软件组件之间发送、存储和接收任何规模的消息，而不会丢失消息，并且无需其他服务即可保持可用。使用 AWS 控制台、命令行界面或您选择的 SDK 和三个简单的命令，在几分钟内即可开始使用 SQS。
SQS 提供两种消息队列类型。标准队列提供最高吞吐量、最大努力排序和至少一次传送。SQS FIFO 队列旨在确保按照消息的发送顺序对消息进行严格一次处理。