How To Create A Classic Load Balancer Using AWS CLI
Hello Everyone
Welcome to CloudAffaire and this is Debjeet.
In the last blog post, we have discussed Classic Load Balancer concepts.
https://cloudaffaire.com/classic-load-balancer-clb/
In this blog post, we will create a Classic Load Balancer using AWS CLI.
How to create a Classic Load Balancer using AWS CLI:
Step 1: Create a custom VPC for your Classic Load Balancer.
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#################################### ## Create A Classic Load Balancer ## #################################### ## Prerequisite: AWS CLI installed and configured with proper access ## https://cloudaffaire.com/category/aws/aws-cli/ ##---------------------------------- ## Create custom vpc for your clb ## ##---------------------------------- ## Create a directory for this demo mkdir aws_clb_demo && cd aws_clb_demo ## Create a VPC with DNS hostname enabled AWS_VPC_ID=$(aws ec2 create-vpc \ --cidr-block 10.0.0.0/16 \ --query 'Vpc.{VpcId:VpcId}' \ --output text) && aws ec2 modify-vpc-attribute \ --vpc-id $AWS_VPC_ID \ --enable-dns-hostnames "{\"Value\":true}" ## Create two public subnets AWS_SUBNET_PUBLIC_ONE_ID=$(aws ec2 create-subnet \ --vpc-id $AWS_VPC_ID --cidr-block 10.0.1.0/24 \ --availability-zone ap-south-1a --query 'Subnet.{SubnetId:SubnetId}' \ --output text) && AWS_SUBNET_PUBLIC_TWO_ID=$(aws ec2 create-subnet \ --vpc-id $AWS_VPC_ID --cidr-block 10.0.2.0/24 \ --availability-zone ap-south-1b --query 'Subnet.{SubnetId:SubnetId}' \ --output text) && aws ec2 modify-subnet-attribute \ --subnet-id $AWS_SUBNET_PUBLIC_ONE_ID \ --map-public-ip-on-launch && aws ec2 modify-subnet-attribute \ --subnet-id $AWS_SUBNET_PUBLIC_TWO_ID \ --map-public-ip-on-launch ## Create an Internet Gateway AWS_INTERNET_GATEWAY_ID=$(aws ec2 create-internet-gateway \ --query 'InternetGateway.{InternetGatewayId:InternetGatewayId}' \ --output text) && aws ec2 attach-internet-gateway \ --vpc-id $AWS_VPC_ID \ --internet-gateway-id $AWS_INTERNET_GATEWAY_ID ## Create a route table AWS_CUSTOM_ROUTE_TABLE_ID=$(aws ec2 create-route-table \ --vpc-id $AWS_VPC_ID \ --query 'RouteTable.{RouteTableId:RouteTableId}' \ --output text ) && aws ec2 create-route \ --route-table-id $AWS_CUSTOM_ROUTE_TABLE_ID \ --destination-cidr-block 0.0.0.0/0 \ --gateway-id $AWS_INTERNET_GATEWAY_ID ## Associate the public subnet with route table AWS_ROUTE_TABLE_ASSOID_ONE=$(aws ec2 associate-route-table \ --subnet-id $AWS_SUBNET_PUBLIC_ONE_ID \ --route-table-id $AWS_CUSTOM_ROUTE_TABLE_ID \ --query 'AssociationId' \ --output text) && AWS_ROUTE_TABLE_ASSOID_TWO=$(aws ec2 associate-route-table \ --subnet-id $AWS_SUBNET_PUBLIC_TWO_ID \ --route-table-id $AWS_CUSTOM_ROUTE_TABLE_ID \ --query 'AssociationId' \ --output text) ## Create a security group aws ec2 create-security-group \ --vpc-id $AWS_VPC_ID \ --group-name myvpc-security-group \ --description 'My VPC non default security group' ## Get security group ID's AWS_DEFAULT_SECURITY_GROUP_ID=$(aws ec2 describe-security-groups \ --filters "Name=vpc-id,Values=$AWS_VPC_ID" \ --query 'SecurityGroups[?GroupName == `default`].GroupId' \ --output text) && AWS_CUSTOM_SECURITY_GROUP_ID=$(aws ec2 describe-security-groups \ --filters "Name=vpc-id,Values=$AWS_VPC_ID" \ --query 'SecurityGroups[?GroupName == `myvpc-security-group`].GroupId' \ --output text) ## Create security group ingress rules aws ec2 authorize-security-group-ingress \ --group-id $AWS_CUSTOM_SECURITY_GROUP_ID \ --ip-permissions '[{"IpProtocol": "tcp", "FromPort": 22, "ToPort": 22, "IpRanges": [{"CidrIp": "0.0.0.0/0", "Description": "Allow SSH"}]}]' && aws ec2 authorize-security-group-ingress \ --group-id $AWS_CUSTOM_SECURITY_GROUP_ID \ --ip-permissions '[{"IpProtocol": "tcp", "FromPort": 80, "ToPort": 80, "IpRanges": [{"CidrIp": "0.0.0.0/0", "Description": "Allow HTTP"}]}]' |
Step 2: Create two EC2 instance that will act as a target for your Classic load balancer.
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##------------------------------------------------------- ## Create two ec2 instances your CLB registered target ## ##------------------------------------------------------- ## Get Amazon Linux 2 latest AMI ID AWS_AMI_ID=$(aws ec2 describe-images \ --owners 'amazon' \ --filters 'Name=name,Values=amzn2-ami-hvm-2.0.????????-x86_64-gp2' 'Name=state,Values=available' \ --query 'sort_by(Images, &CreationDate)[-1].[ImageId]' \ --output 'text') ## Create a key-pair aws ec2 create-key-pair \ --key-name myvpc-keypair \ --query 'KeyMaterial' \ --output text > myvpc-keypair.pem && chmod 400 myvpc-keypair.pem ## Create user data to configure LAMP stack vi myuserdataone.txt ----------------------- #!/bin/bash sudo yum install -y httpd sudo systemctl start httpd sudo usermod -a -G apache ec2-user sudo chown -R ec2-user:apache /var/www sudo chmod 2775 /var/www sudo find /var/www -type d -exec chmod 2775 {} \; sudo find /var/www -type f -exec chmod 0664 {} \; sudo echo "hello from instance one" > /var/www/html/index.html ----------------------- :wq vi myuserdatatwo.txt ----------------------- #!/bin/bash sudo yum install -y httpd sudo systemctl start httpd sudo usermod -a -G apache ec2-user sudo chown -R ec2-user:apache /var/www sudo chmod 2775 /var/www sudo find /var/www -type d -exec chmod 2775 {} \; sudo find /var/www -type f -exec chmod 0664 {} \; sudo echo "hello from instance two" > /var/www/html/index.html ----------------------- :wq ## Create two EC2 instance in two public subnet AWS_EC2_INSTANCE_ONE_ID=$(aws ec2 run-instances \ --image-id $AWS_AMI_ID \ --instance-type t2.micro \ --key-name myvpc-keypair \ --monitoring "Enabled=false" \ --security-group-ids $AWS_CUSTOM_SECURITY_GROUP_ID \ --subnet-id $AWS_SUBNET_PUBLIC_ONE_ID \ --user-data file://myuserdataone.txt \ --private-ip-address 10.0.1.10 \ --query 'Instances[0].InstanceId' \ --output text) && AWS_EC2_INSTANCE_TWO_ID=$(aws ec2 run-instances \ --image-id $AWS_AMI_ID \ --instance-type t2.micro \ --key-name myvpc-keypair \ --monitoring "Enabled=false" \ --security-group-ids $AWS_CUSTOM_SECURITY_GROUP_ID \ --subnet-id $AWS_SUBNET_PUBLIC_TWO_ID \ --user-data file://myuserdatatwo.txt \ --private-ip-address 10.0.2.10 \ --query 'Instances[0].InstanceId' \ --output text) ## It will take some time for the instances to get running |
Step 3: Create your Classic Load Balancer.
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##-------------------------------- ## Create classic load balancer ## ##-------------------------------- ## Create the classic load balancer AWS_CLB_DNS=$(aws elb create-load-balancer \ --load-balancer-name my-classic-load-balancer \ --listeners Protocol=HTTP,LoadBalancerPort=80,InstanceProtocol=HTTP,InstancePort=80 \ --subnets $AWS_SUBNET_PUBLIC_ONE_ID $AWS_SUBNET_PUBLIC_TWO_ID \ --security-groups $AWS_CUSTOM_SECURITY_GROUP_ID \ --query 'DNSName' \ --output text) ## Get details for your classic load balancer aws elb describe-load-balancers \ --load-balancer-name my-classic-load-balancer ## Check your classic load balancer configuration options aws elb describe-load-balancer-attributes \ --load-balancer-name my-classic-load-balancer \ --output table ## Check your classic load balancer additional configuration options ## Returns sticky session and proxy connection information ## Since we have not configured these, returns empty set aws elb describe-load-balancer-policies \ --load-balancer-name my-classic-load-balancer ## Check your classic load balancer health check configuration options aws elb describe-load-balancers \ --load-balancer-name my-classic-load-balancer \ --query 'LoadBalancerDescriptions[0].HealthCheck' \ --output table ## Register both the instances with your classic load balancer aws elb register-instances-with-load-balancer \ --load-balancer-name my-classic-load-balancer \ --instances $AWS_EC2_INSTANCE_ONE_ID $AWS_EC2_INSTANCE_TWO_ID ## Check the health of your registered instances aws elb describe-instance-health \ --load-balancer-name my-classic-load-balancer ## Open the DNS name of your CLB (below output) in your browser and hit refresh several time ## Or curl your CLB DNS name repetedly echo $AWS_CLB_DNS curl $AWS_CLB_DNS ## Responce from both the instances |
Observation: You will get response form both instance one and instance two as your curl/browser request is forwarded by CLB to registered instance in the backends.
Step 4: Cleanup
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##----------- ## Cleanup ## ##----------- ## Deregister both the instances with your classic load balancer aws elb deregister-instances-from-load-balancer \ --load-balancer-name my-classic-load-balancer \ --instances $AWS_EC2_INSTANCE_ONE_ID $AWS_EC2_INSTANCE_TWO_ID ## Delete your classic load balancer aws elb delete-load-balancer \ --load-balancer-name my-classic-load-balancer ## Terminate the ec2 instances aws ec2 terminate-instances \ --instance-ids $AWS_EC2_INSTANCE_ONE_ID && aws ec2 terminate-instances \ --instance-ids $AWS_EC2_INSTANCE_TWO_ID ## Delete key pair aws ec2 delete-key-pair \ --key-name myvpc-keypair ## Delete custom security group (once instances are terminated) aws ec2 delete-security-group \ --group-id $AWS_CUSTOM_SECURITY_GROUP_ID ## Delete internet gateway aws ec2 detach-internet-gateway \ --internet-gateway-id $AWS_INTERNET_GATEWAY_ID \ --vpc-id $AWS_VPC_ID && aws ec2 delete-internet-gateway \ --internet-gateway-id $AWS_INTERNET_GATEWAY_ID ## Disassociate the subnets from custom route table aws ec2 disassociate-route-table \ --association-id $AWS_ROUTE_TABLE_ASSOID_ONE && aws ec2 disassociate-route-table \ --association-id $AWS_ROUTE_TABLE_ASSOID_TWO ## Delete custom route table aws ec2 delete-route-table \ --route-table-id $AWS_CUSTOM_ROUTE_TABLE_ID ## Delete the public subnets aws ec2 delete-subnet \ --subnet-id $AWS_SUBNET_PUBLIC_ONE_ID && aws ec2 delete-subnet \ --subnet-id $AWS_SUBNET_PUBLIC_TWO_ID ## Delete the vpc aws ec2 delete-vpc \ --vpc-id $AWS_VPC_ID ## Delete the directory used in this demo cd .. && rm -rf aws_clb_demo |
Hope you have enjoyed this article. With this, we are concluding our introductory series in AWS Elastic Load Balancing. There are lots of features available under Classic Load Balancing but as mentioned in the previous blog post, Classic Load Balancer is a legacy load balancer offering from AWS and is replaced by Application Load Balancer and Network Load Balancer with additional features which we already covered in previous blogs. Hence we are not covering Classic Load Balancer any further.
All the public cloud providers are changing the console user interface rapidly and due to this some of the screenshots used in our previous AWS blogs are no longer relevant. Hence, we have decided that from now onwards most of the demo will be done programmatically. Let us know your feedback on this in the comment section.
To get more details on AWS ELB, please refer below AWS documentation
https://docs.aws.amazon.com/elasticloadbalancing/index.html