Elastic load balancer
Last updated
Last updated
Elastic load balancer is a managed service which can spread load across multiple services.
It is a regional service, making them highly available.
Exposes a single point of access for DNS to your application.
AWS takes care of the infra and upgrades of load balancers.
Provides SSL termination for your websites.
Offers health checks (health endpoints), to make sure the requests are forwarded only to health instances.
Can be setup as public or private load balancer depending on the scheme.
Provides high availability across zones.
Can enforce stickiness with cookies.
In general, group of AWS resources which would receive traffic from load balancer.
Allows grouping of
EC2 instances
ECS tasks
IP addresses (must be private)
Lambda function
Application load balancer
A listener is a process that checks for connection requests, using the protocol and port that you configure.
The rules that you define for a listener determine how the load balancer routes requests to its registered targets.
To enable load balancer to know if the instance is healthy and can forward traffic to it, health checks play crucial role.
Health check is done using /health endpoint (typically) running on port 4567 using http protocol.
They are done at target group level.
Health checks need to be configured when creating a target group before registering targets in to the target group.
Supports HTTP, HTTPS, TCP, SSL.
Only supported one SSL certificate for HTTPS based listeners.
Newer generation, 2016.
Works on layer 7 of OSI model, supports HTTP/1.x, HTTP/2 HTTPS, WebSocket, gRPC.
Supports redirect from HTTP to HTTPS.
Great fit for microservices and container-based application.
Supports routing to different target groups based on,
Path in URL
Hostname in URL
Query strings and headers
Port mapping feature allow to redirect to a dynamic port in ECS.
The IP address of the client is available in the header X-Forwarded-For, the port of the client in header X-Forwarded-Port, the protocol in header X-Forwarded-Proto.
Target groups can be EC2 instances, ECS Task, Lambda functions (requests are translated to JSON event), Private IP Address.
Health checks are done at target group level.
ALB as has a fixed hostname of the form xxx.region.elb.amazonaws.com.
Newer generation, 2017.
Not available in free-tier option.
Target groups can be EC2 instances, Private IP Addresses, ALB.
Layer 4 load balancer, supports TCP, TLS, UDP.
High performance, with ultra-lower latency.
Has one static IP per AZ, with ability to assign elastic IP to each AZ.
Health check supports TCP, HTTP and HTTPS.
Newer generation, introduced in 2020.
Operates at network layer 3.
Target groups can be EC2 instances, Private IP Addresses.
Can be used to deploy, manage and scale a fleet of 3rd party virtual appliances which includes Firewalls, IDPS, Deep packet inspection etc.
Uses GENEVE protocol at port 6081.
Read more about it .
Read more about it .
Deprecated and , old generation (v1).
