How to create an Application Load Balancer Using AWS CLI
Hello Everyone
Welcome to CloudAffaire and this is Debjeet.
In the last blog post we have discussed Application Load Balancer concepts.
https://cloudaffaire.com/application-load-balancer-alb/
In this blog post we will create an Application Load Balancer using AWS CLI.
How to create an Application Load Balancer using AWS CLI:
Step 1: Create a custom VPC with two public subnets, and security group to allow http access in port 80.
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###################################### ## Create application load balancer ## ###################################### ## Prerequisite: AWS CLI installed and configured with proper access ## https://cloudaffaire.com/category/aws/aws-cli/ ##---------------------------------- ## Create custom vpc for your alb ## ##---------------------------------- ## Create a VPC AWS_VPC_ID=$(aws ec2 create-vpc \ --cidr-block 10.0.0.0/16 \ --query 'Vpc.{VpcId:VpcId}' \ --output text) ## Enable DNS hostname for your VPC aws ec2 modify-vpc-attribute \ --vpc-id $AWS_VPC_ID \ --enable-dns-hostnames "{\"Value\":true}" ## Add a tag to the VPC aws ec2 create-tags \ --resources $AWS_VPC_ID \ --tags "Key=Name,Value=myvpc" ## Create two public subnets AWS_SUBNET_PUBLIC_ONE_ID=$(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) ## Enable Auto-assign Public IP on Public Subnets 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 ## Add a tag to public subnets aws ec2 create-tags \ --resources $AWS_SUBNET_PUBLIC_ONE_ID \ --tags "Key=Name,Value=myvpc-public-subnet-one" aws ec2 create-tags \ --resources $AWS_SUBNET_PUBLIC_TWO_ID \ --tags "Key=Name,Value=myvpc-public-subnet-two" ## Create an Internet Gateway AWS_INTERNET_GATEWAY_ID=$(aws ec2 create-internet-gateway \ --query 'InternetGateway.{InternetGatewayId:InternetGatewayId}' \ --output text) ## Attach Internet gateway to your VPC aws ec2 attach-internet-gateway \ --vpc-id $AWS_VPC_ID \ --internet-gateway-id $AWS_INTERNET_GATEWAY_ID ## Add a tag to the Internet-Gateway aws ec2 create-tags \ --resources $AWS_INTERNET_GATEWAY_ID \ --tags "Key=Name,Value=myvpc-internet-gateway" ## Create a route table AWS_CUSTOM_ROUTE_TABLE_ID=$(aws ec2 create-route-table \ --vpc-id $AWS_VPC_ID \ --query 'RouteTable.{RouteTableId:RouteTableId}' \ --output text ) ## Create route to Internet Gateway 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 $AWS_CUSTOM_SECURITY_GROUP_ID \ --ip-permissions '[{"IpProtocol": "tcp", "FromPort": 80, "ToPort": 80, "IpRanges": [{"CidrIp": "0.0.0.0/0", "Description": "Allow HTTP"}]}]' |
Step 2: Create two EC2 instance that will act as a target for your application load balancer.
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##-------------------------------------------------- ## Create two ec2 instances your alb target group ## ##-------------------------------------------------- ## Get Amazon Linux 2 latest AMI ID AWS_AMI_ID=$(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 ## Change access to key pair to make it secure chmod 400 myvpc-keypair.pem ## Create user data to configure LAMP stack vi myuserdataone.txt ----------------------- #!/bin/bash sudo yum update -y sudo amazon-linux-extras install -y lamp-mariadb10.2-php7.2 php7.2 sudo yum install -y httpd mariadb-server 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 update -y sudo amazon-linux-extras install -y lamp-mariadb10.2-php7.2 php7.2 sudo yum install -y httpd mariadb-server 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) ## Check if the instance one is running ## It will take some time for the instance to get ready aws ec2 describe-instance-status \ --instance-ids $AWS_EC2_INSTANCE_ONE_ID --output text AWS_EC2_INSTANCE_TWO_ID=$(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) ## Check if the instance two is running ## It will take some time for the instance to get ready aws ec2 describe-instance-status \ --instance-ids $AWS_EC2_INSTANCE_TWO_ID --output text ## Add a tag to the ec2 instances aws ec2 create-tags \ --resources $AWS_EC2_INSTANCE_ONE_ID \ --tags "Key=Name,Value=myvpc-ec2-instance-one" aws ec2 create-tags \ --resources $AWS_EC2_INSTANCE_TWO_ID \ --tags "Key=Name,Value=myvpc-ec2-instance-two" |
Step 3: Create your Application Load Balancer
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##------------------------------------ ## Create application load balancer ## ##------------------------------------ ## Create the application load balancer AWS_ALB_ARN=$(aws elbv2 create-load-balancer \ --name my-application-load-balancer \ --subnets $AWS_SUBNET_PUBLIC_ONE_ID $AWS_SUBNET_PUBLIC_TWO_ID \ --security-groups $AWS_CUSTOM_SECURITY_GROUP_ID \ --query 'LoadBalancers[0].LoadBalancerArn' \ --output text) ## Check the status of load balancer aws elbv2 describe-load-balancers \ --load-balancer-arns $AWS_ALB_ARN \ --query 'LoadBalancers[0].State.Code' \ --output text ## Once the ALB status is active, get the DNS name for your ALB AWS_ALB_DNS=$(aws elbv2 describe-load-balancers \ --load-balancer-arns $AWS_ALB_ARN \ --query 'LoadBalancers[0].DNSName' \ --output text) && echo $AWS_ALB_DNS ## Create the target group for your ALB AWS_ALB_TARGET_GROUP_ARN=$(aws elbv2 create-target-group \ --name my-alb-targets \ --protocol HTTP --port 80 \ --vpc-id $AWS_VPC_ID \ --query 'TargetGroups[0].TargetGroupArn' \ --output text) ## Register both the instances in the target group aws elbv2 register-targets --target-group-arn $AWS_ALB_TARGET_GROUP_ARN \ --targets Id=$AWS_EC2_INSTANCE_ONE_ID Id=$AWS_EC2_INSTANCE_TWO_ID ## Create a listener for your load balancer with a default rule that forwards requests to your target group AWS_ALB_LISTNER_ARN=$(aws elbv2 create-listener --load-balancer-arn $AWS_ALB_ARN \ --protocol HTTP --port 80 \ --default-actions Type=forward,TargetGroupArn=$AWS_ALB_TARGET_GROUP_ARN \ --query 'Listeners[0].ListenerArn' \ --output text) ## Verify the health of the registered targets for your target group aws elbv2 describe-target-health --target-group-arn $AWS_ALB_TARGET_GROUP_ARN ## Open the DNS name of your ALB (below output) in your browser and hit refresh several time echo $AWS_ALB_DNS ## Or curl your ALB DNS name repeatedly from your console curl $AWS_ALB_DNS |
Observation: You will get a response from both instance one and instance two as your curl/browser request is forwarded by ALB to target backends.
Step 4: Cleanup
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##----------- ## Cleanup ## ##----------- ## Delete the listener aws elbv2 delete-listener \ --listener-arn $AWS_ALB_LISTNER_ARN ## Deregister targets aws elbv2 deregister-targets \ --target-group-arn $AWS_ALB_TARGET_GROUP_ARN \ --targets Id=$AWS_EC2_INSTANCE_ONE_ID Id=$AWS_EC2_INSTANCE_TWO_ID ## Delete target group aws elbv2 delete-target-group \ --target-group-arn $AWS_ALB_TARGET_GROUP_ARN ## Delete Application Load Balancer aws elbv2 delete-load-balancer \ --load-balancer-arn $AWS_ALB_ARN ## Terminate the ec2 instances aws ec2 terminate-instances \ --instance-ids $AWS_EC2_INSTANCE_ONE_ID && rm -f myuserdataone.txt aws ec2 terminate-instances \ --instance-ids $AWS_EC2_INSTANCE_TWO_ID && rm -f myuserdatatwo.txt ## Delete key pair aws ec2 delete-key-pair \ --key-name myvpc-keypair && rm -f myvpc-keypair.pem ## 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 |
Hope you have enjoyed this article, In the next blog post, we will discuss different advance routing options available in Application Load Balancer.
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