Carlos Grillet carlosgrillet

OpenSSL Cheatsheet

Targets OpenSSL 3.x. [3.0+] / [1.1.1+] mark version-dependent flags.

Keys

openssl genpkey -algorithm EC -pkeyopt ec_paramgen_curve:P-256 -out key.pem
openssl genpkey -algorithm ed25519 -out key.pem
openssl genpkey -algorithm RSA -pkeyopt rsa_keygen_bits:3072 -out key.pem

Fedora Service Deployment Guide

1. System User Setup

Never run a service as root or a standard login user. Create a dedicated system user.

# -r: System account (no aging, UID in system range)
# -s /sbin/nologin: No interactive login shell for security
# -U: Create a group with the same name as the user
# -m -d: Create and set the home directory
sudo useradd -rs /sbin/nologin -Umd /var/lib/myservice myservice

Rust Ownership: The Complete Mental Model

Rust rules are simple to understand but can confusing to implement.

Part 1: ELI5 (Explain Like I'm 5)

The Apartment Analogy

Think of every value in Rust as a physical apartment key — not a copy, the only key.

strace - System Call Tracer

Synopsis

strace [OPTIONS] { -p PID | PROG [ARGS] }
strace -c [OPTIONS] { -p PID | PROG [ARGS] }

📂 File & Directory Operations

`ls`: List directory contents

$ ls
Desktop  Documents  Downloads

`cp`: Copy files or directories

How to Set Up HAProxy as a Load Balancer for Kubernetes High Availability (HA) Clusters

This guide explains how to configure HAProxy as a load balancer for Kubernetes clusters.

Why Use a Load Balancer?

A load balancer is important for Kubernetes clusters because:

High Availability: It ensures that if one control plane node fails, traffic is redirected to other working nodes.
Better Performance: It distributes traffic evenly across multiple nodes, preventing overload on a single node.
Simplified Access: Instead of connecting to individual control plane nodes, you can use a single entry point (the load balancer).

	# Legend:
	# <tool_name> the name of your binary, e.g. gotool
	# <owner> the owner of the tool repository, e.g. privGo
	# <repo> the tool repository
	# <tap_owner> the owner of the homebrew tap repository
	# <tap> the name of the homebrew tap
	# <license> the license of your tool
	# <project_description> description of your tool
	#
	# Example:

	use std::fmt;

	struct Node<T> {
	value: T,
	next: Option<Box<Node<T>>>,
	}

	pub struct List<T> {
	head: Option<Box<Node<T>>>,
	len: usize,

	#!/usr/bin/env bash

	set -euo pipefail

	if [[ $# -eq 0 ]]; then
	echo "Error: Please provide a project name." >&2
	echo "Usage: $0 <name>" >&2
	exit 1
	fi

	# cloud-config
	users:
	- name: mikrotik
	groups: sudo
	shell: /bin/bash

	packages:
	- wget
	- gzip