Vassil Kalkov kalkov

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) /

Simple WireGuard configuration

1 server, 2 clients

Getting started

Install Wireguard on all machines.

Generate all keys

layout

title

description

Purpose

Postgres Cheatsheet

This is a collection of the most common commands I run while administering Postgres databases. The variables shown between the open and closed tags, "<" and ">", should be replaced with a name you choose. Postgres has multiple shortcut functions, starting with a forward slash, "". Any SQL command that is not a shortcut, must end with a semicolon, ";". You can use the keyboard UP and DOWN keys to scroll the history of previous commands you've run.

Setup

installation, Ubuntu

http://www.postgresql.org/download/linux/ubuntu/ https://help.ubuntu.com/community/PostgreSQL

A minimal HTTP server in python. It sends a JSON Hello World for GET requests, and echoes back JSON for POST requests.

python server.py 8009
Starting httpd on port 8009...

curl http://localhost:8009
{"received": "ok", "hello": "world"}

PSQL

Magic words:

psql -U postgres

Some interesting flags (to see all, use -h or --help depending on your psql version):

-E: will describe the underlaying queries of the \ commands (cool for learning!)
-l: psql will list all databases and then exit (useful if the user you connect with doesn't has a default database, like at AWS RDS)

Zero downtime deploys with unicorn + nginx + runit + rvm + chef

Below are the actual files we use in one of our latest production applications at Agora Games to achieve zero downtime deploys with unicorn. You've probably already read the GitHub blog post on Unicorn and would like to try zero downtime deploys for your application. I hope these files and notes help. I am happy to update these files or these notes if there are comments/questions. YMMV (of course).

Other application notes:

Our application uses MongoDB, so we don't have database migrations to worry about as with MySQL or postgresql. That does not mean that we won't have to worry about issues with the database with indexes being built in MongoDB or what have you.
We use capistrano for deployment.

Salient points for each file:

	#!/usr/bin/env node

	/*
	* ModBus read for Noark Ex9EM 1P 1M 80A MO MT Electric Meter
	* https://www.noark.com.hr/en/products/107281
	*/

	////////////////
	// CONFIGURATION
	////////////////

	#!/bin/bash

	# This script will install AMDGPU-PRO OpenCL and Vulkan support.
	#
	# For Ubuntu and it's flavor, just install the package using this command
	# in extracted driver directory instread.
	#
	# ./amdgpu-pro-install --opencl=legacy,pal --headless --no-dkms
	#
	# For Arch Linux or Manjaro, use the opencl-amd or rocm-opencl-runtime on AUR instread.

	# Copyright 2018 Marketplacer. MIT License.

	require 'json'
	require 'active_support/core_ext/class/attribute'
	require 'active_support/log_subscriber'

	module Elk
	class RequestLogSubscriber < ActiveSupport::LogSubscriber
	PAYLOAD_KEYS_TO_COPY = %i{
	controller