In this post, I am writing down some notes from the lecture I am watching on Udemy for CCNA preparation. I am not from the networking background but it is a critical domain that no one can skip if he is serious about computers. The course link is https://www.udemy.com/course/ccna-complete/ Transport Layer - OSI Layer 4 The transport layer’s main responsibilty is to prepare the data packets. It uses either TCP or UDP protocol for this.

I was trying to do some ansible stuff for learning purpose. My tasks was to do some provisioning on multiple hosts. At first I thought to spin up some t2.micro instances but later I realized that I do not have free tier anymore. Naturally I decided to run multiple containers and set them as hosts for my ansible project. Because I wanted to try Redhat based systems I pulled Redhat official image from docker hub Redhat Universal Base Image.

Packer is a tool by HashiCorp that can be used to automate the process of creating Amazon Machine Images (AMIs). One of the benefits of using Packer to create AMIs with your application code pre-installed is that it can help speed up the process of launching EC2 instances in order to meet production traffic needs. This is because Packer allows you to build AMIs in a repeatable and automated way, so that you can quickly and easily launch new instances with your application code already installed and configured.

I was working on a task that requires to update certain tags on all the resources in an AWS account. While there are multiple ways to apporach this problem, I opted to use a AWS native solution AWS Resource Groups Tagging API. It provides a nice simple API to get resources by filters and modify tags on those resources. Another way to achieve this is by putting a Conformance Pack with both rules and possibly a custom lambda based remediation.

Recently I get a chance to use Apache ActiveMQ in one or our services. One of the conditions that we have is that the ActiveMQ server is behind a load balancer. This makes keeping long running connection to the ActiveMQ server impossible as AWS load balancer default times out in 60s if there is no data transfer happens between the two parties. Solution In order to keep the connection active and to be able to instantly receive any message in the subscribed queue we must enable a ping / pong mechanism.