Manage ELB using Python Boto3

 Managing AWS ELB automations using Boto3 Python scripts. 

What is ELB?

ELB automatically distributes incoming network traffic (may be HTTP/HTTPS requests) across multiple EC2 instances running in different Availability Zones.

ELB to EC2 instances

 In this post I will experimenting on the following: 

• Create ELB 
• Apply security group
• Create Health check
• Register instances with ELB  
• Delete ELB services

1. How to Create ELB using Python Boto3 automations?

The create_load_blancer method is used to create a Load Balancer.

object: client refers to elb 

method: create_load_blancer() which requires LoadBalancerName, Listeners that is again a dictionary of Protocol,LoadBalancerPort,InstanceProtocol, InstancePort, And another parameter 'AvailabilityZone' is important that refer to region on which you ar working on.

import boto3
elb_client=boto3.client('elb')

response = elb_client.create_load_blancer(
	LoadBalancerName='vybhava_lb',
	Listeners=[{'Protocol': 'HTTP', 'LoadBalancerPort':80, 'InstanceProtocol':'HTTP', 'InstancePort': 80},
	AvailabilityZone=['ap-south-1a']
	)
print(response)
print(response['DNSName'])

2. Apply security group on ELB using Boto3

object: client refers to elb method: apply_security_groups_to_load_balancer() here we can use existing security group(that is created during EC2 instance creation) can be associated with the ELB as well.

import boto3
elb_client=boto3.client('elb')
response=elb_client.apply_security_groups_to_load_balancer(
	LoadBalancerName='vybhava_lb',
	SecurityGroups='sg-vybhava_lb']
	)
print(response)

3. How to create Health check?

object: client refers to elb method: configure_health_check() without healthcheck there is not strong bonding between ELB and EC2 instances. This will validate to check weather the incoming request should be send to the instance or not based on the parameters here we provide.

import boto3
elb_client=boto3.client('elb')
health_check_resp=elb_client.configure_health_check(
	LoadBalancerName =  'vybhava_lb',
	HealthCheck={
		'Target':'TCP:22',
		'Interval':10,
		'Timeout':5,
		'UnhealthyThreshold':5,
		'HealthyThreshould': 5
	}
	
print(health_check_resp)	

The health_check_resp object output c should have 200. Http code for success.

4. How to register instance with ELB services?

EC2 Instance(s) will be attached to ELB object: client method: register_instances_with_load_balancer

import boto3
elb_client=boto3.client('elb')

instanceid=input('Please enter instance id to attach to ELB:')
attachinstance=elb_client.register_instances_with_load_balancer(
	LoadBalancerName='vybhava_lb',
	Instances=[	{
		'InstanceId': instanceid,
	}	]
)
print(attachinstance)

Observe that 'Instance Count' value changes according to attached number of instances. In the bottom tabs look for 'Instances'.

5. How to deregister instance from ELB using Boto3?

De-register EC2 instances from ELB, its reverse process what we did for registration.The object: client method: register_instances_with_load_balancer

import boto3
elb_client=boto3.client('elb')

deattachinstance=elb_client.deregister_instances_with_load_balancer(
LoadBalancerName='vybhava_lb',
	Instances=[	{
		'InstanceId': instanceid,
	}	]
)
print(deattachinstance)

6. How to delete ELB service using Boto3?

The removal of elb can be performed on elb_client, to delete ELB we need to use param for delete_loadbalancer is existing elb services name.

object: client refer to elb service

method: delete_loadbalancer()

import boto3
elb_client=boto3.client('elb')

response=elb_client.delete_loadbalancer(LoadBalancerName='vybhava_lb')
print(response)

Goto the aws console and confirm that no ELB in that region where we did all the above. 

 Refrences: https://unbiased-coder.com/boto3-load-balancer-guide/