Use AWS service to design a web server infrastructure where a has a external facing URI/endpoint and forwards incoming HTTP request to 2 Node.js web servers. The two Node servers are expected to run in containers. Once the user visits the URI, the web page shows how many requests are processed by each server. It can be as simple as follows:
Web server 1 IP: 19999 requests processed
Web server 2 IP: 33333 requests processed
I haven't been able to find the right CloudWatch metrics to query the count of requests processed by each server. I only found the average and sum of requests. If I later find the right metric to use, I can try make an API request to the CloudWatch endpoints as refenced in the following documentation: https://docs.aws.amazon.com/AmazonCloudWatch/latest/APIReference/making-api-requests.html
- AWS: Sign in to Console
- ECS: Set up cluster of two container instances (region: us-west-2, type: t2.micro)
- Node.js: Run Node http server on instances (customer port 3000, server1.js & server2.js)
- ELB: Create Application Load Balancer and Target Group (listens on HTTP port 80)
- Verify: Visit Load Balancer's DNS address and see if it routes to either server alternatively (note that visit count increments)
- CloudWatch: Define application metrics to be monitored (RequestCountPerTarget vs. RequestCount)
Visit load balancer DNS @ http://ecs-load-balancer-1166260154.us-west-2.elb.amazonaws.com/
I use a tool called forever which is a simple CLI for ensuring that a given script runs continuously. Thus I can run the two Node.js server continuously by triggering command forever start server.js and the demo would still work even when I close the Putty sessions.
I implemnted a visitor counter in both Node.js server. The value of counter will increment by 1 whenever a user visits the server running on port 3000. Thus when browsing the Load Balancer (ELB) DNS address, we see the number of HTTP requests made to either server1 or server2.
-
Setting Up Node.js on an Amazon EC2 Instance https://docs.aws.amazon.com/sdk-for-javascript/v2/developer-guide/setting-up-node-on-ec2-instance.html
-
Launching an Amazon ECS Container Instance https://docs.aws.amazon.com/AmazonECS/latest/developerguide/launch_container_instance.html
-
Creating an Application Load Balancer https://docs.aws.amazon.com/AmazonECS/latest/developerguide/create-application-load-balancer.html
-
What is Amazon CloudWatch? https://docs.aws.amazon.com/AmazonCloudWatch/latest/monitoring/WhatIsCloudWatch.html
-
EC2 Container Service https://github.com/awslabs/amazon-ecs-nodejs-microservices/tree/master/2-containerized
-
AWS Application Load Balancer (ALB) https://www.bogotobogo.com/DevOps/AWS/aws-ELB-ALB-Application-Load-Balancer-ECS.php
-
What is Amazon Elastic Container Service? https://docs.aws.amazon.com/AmazonECS/latest/developerguide/Welcome.html