Muhammad Ardivan muhammad-asn

Motivation

When attempting to debug an issue, it can be challenging to reproduce the problem on the machine used in the CI/CD process, especially if it is different from the local development environment. Because there is no direct access to the runner machine in cloudbuild, there is alternative way by applying the reverse-shell method that allows gaining access to the CI/CD environment.

Note: Establishing a reverse shell should only be done for the purpose of debugging and testing and not to be misused.

On client (can be accessed from public)

$ sudo apt-get install rlwrap # readline wrapper for nice tty

Load tests

Injector

wrk is the binary used as injector, always used with these options:

./wrk -t12 -c1000 -d15s http://127.0.0.1:8080/

Results

How to create Telegram Bot and send messages to your group

Create Telegram bot:

Search for user @BotFather in Telegram app. Type /help in BotFather chat and wait for the reply. Type in the chat:

/newbot

or select /newbot command from Help text. Answer few setup questions:

Memory LIMIT and REQUEST in Containers and JVM

Do you run a JVM inside a container on Kubernetes (or maybe OpenShift)?
Do you struggle with REQUEST and LIMIT parameters?
Do you know the impact of those parameters on your JVM?
Have you met OOM Killer?

Hope you will find answers to these questions in this example-based article.

How to set up JVM Heap size in a Container

CPU: percentage of limit

A lot of people land when trying to find out how to calculate CPU usage metric correctly in prometheus, myself included! So I'll post what I eventually ended up using as I think it's still a little difficult trying to tie together all the snippets of info here and elsewhere.

This is specific to k8s and containers that have CPU limits set.

To show CPU usage as a percentage of the limit given to the container, this is the Prometheus query we used to create nice graphs in Grafana:

sum(rate(container_cpu_usage_seconds_total{name!~".*prometheus.*", image!="", container_name!="POD"}[5m])) by (pod_name, container_name) /

Getting Started

vi editor cheat sheet
netstat
netcat
View Kernel IP routing table
tcpdump
tcpping
Creating users, group and assigning users to groups
Assign Sudo Permissions
User Accounts

	# This script will explain how to transfer a file to EC2 using SSM ONLY!

	# You will need to have permission to run SSM commands on the target machine and have sudo access as well

	# Infos
	INSTANCE_ID=i-1234567890
	FILE_NAME=the_file.tar.gz

	# Step 1: Run command on machine to install netcat and dump from port to filename
	# < Start session

	# http://karma-runner.github.io/1.0/dev/git-commit-msg.html
	bash -c "! git log -100 --pretty=format:%s \| egrep --color=auto -v '^(((feat\|fix\|docs\|style\|refactor\|test\|chore)(\(\w+\))?:\s)\|Merge).*'"

	FROM python:3-onbuild

	EXPOSE 8000

	CMD ["./server.py"]