Welcome to The Weekly Journal. Here I will try to compile link,blogposts etc which I read that week. This week I will start with a little look back on 2020. 2020 like everyone else I remained constantly worrying, but I did manage to read some books and try out few things as follows 12 week a year - I can say till now the most influencing blinks that I read.

Feign using consul as discovery service is easy to setup thanks to Spring Autoconfigurations, but let’s see how this magic is actually done - Spring cloud open feign comes with FeignLoadBalancerAutoConfiguration . If we see closely it imports three more LoadBalancerAutoConfigurations HttpClientFeignLoadBalancerConfiguration, OkHttpFeignLoadBalancerConfiguration, DefaultFeignLoadBalancerConfiguration If classpath has Apache http client then it uses HttpClientFeignLoadBalancerConfiguration , if path has Ok http client then it uses OkHttpFeignLoadBalancerConfiguration otherwise uses it DefaultFeignLoadBalancerConfiguration which in turn uses Apache Http client.

AWS Lambda is the serverless offering from amazon. In serverless the provider is responsible for settung up a runtime as and when needed for the deployed application/function to run. Typically these are small functions which are quick to start up and finish their task. Lambdas when invoked, has a small startup overhead. This startup overhead involves fetching the function artifact from S3 , setting up networking, starting up the application. Java applications often suffer from this cold start up problem , and depends on application this can go up quite a bit.

Spring Boot Actuator Health endpoint since 2.3.0 comes with two health groups Liveness and Readiness. Actuator Health points are being used to reflect the status of the application. Spring Boot also provides a way to add multiple health indicators together and form a group. As a continuation to this concept Spring Boot provides two HealthIndicator LivenessStateIndicator and ReadinessStateIndicator. These two indicators are added to liveness and readiness group respectively by AvailabilityProbesHealthEndpointGroups.

EKS is managed kubernetes service by AWS. This post will describe networking setup for EKS cluster. EKS have two options public cluster and private-public cluster. In the public cluster all nodes get a public IP and they can access internet traffic and vice versa. In public-private scheme nodes are all in private subnet and services are exposed via Loadbalancers in public subnet. We will see network configuration about public-private scheme. Below is the conceptual design of the cluster

In order to explore more about deploying on ECS using terraform and github action I created a small project but as I try to deploy it on AWS ECS I found some interesting issue. So I created a services in a subnet , the subnet has rule that route all internet traffic to an internet gateway. The service has a simple task. I created all the infrastructure using terraform and deployed using github.