Kien Nguyen ntk148v

Arch Linux

GRUB Installation

Be sure to replace /dev/sda with the name of the drive (n.b. not the partition) containing Arch.

# pacman -S grub-bios intel-ucode
# grub-install /dev/sda
# mkinitcpio -p linux

System Design Cheatsheet

Picking the right architecture = Picking the right battles + Managing trade-offs

Basic Steps

Clarify and agree on the scope of the system

User cases (description of sequences of events that, taken together, lead to a system doing something useful)
- Who is going to use it?
- How are they going to use it?

Overview

Some notes about:

Explaining why current day Linux memory swap thrashing still happens (as of 2016).
Mitigating "stop the world" type thrashing issues on a Linux workstation when it's under high memory pressure and where responsiveness is more important than process completion.
Prioritizing and limiting memory use.
Older ulimit versus newer CGroup options.

These notes assume some basic background knowledge about memory management, ulimits and cgroups.

SSH CA use-case with Vault

In this scenario we are going to set up Vault to sign SSH keys using an internal CA. We will configure the SSH secrets engine and create a CA within Vault. We will then configure an SSH server to trust the CA key we just created. Finally we will attempt to SSH using a private key, and a public key signed by Vault SSH CA.

Prerequisites

This guide assumes you have already provisioned a Vault server, SSH host using OpenSSH server, and a SSH client machine.
The client system must be able to reach the Vault server and the OpenSSH server.
We will refer to these systems respectively as:
VAULT_SERVER

EDIT from 2019: Hi folks. I wrote this gist for myself and some friends, and it seems like it's gotten posted somewhere that's generated some (ahem, heated) discussion. ~~The whitespace was correct when it was posted, and since then GitHub changed how it formats <pre> tags. Look at the raw text if you care about this. I'm sure someone could tell me how to fix it, but~~ (thank you @anzdaddy for suggesting a formatting workaround) honestly this is a random throwaway gist from 2015, and someone more knowledgable about this comparison should just write a proper blog post about it. If you comment here I'll hopefully see it and stick a link to it up here. Cheers. @oconnor663

Here's the canonical TOML example from the TOML README, and a YAML version of the same.

title = "TOML Example"

	package main

	import (
	"context"
	"fmt"
	"log"
	"net/http"
	"os"
	"os/signal"
	"strconv"

	package main

	import (
	"context"
	"flag"
	"fmt"
	"log"
	"net/http"
	"os"
	"os/signal"

	package main

	import (
	"context"
	"fmt"
	"os"
	"os/signal"
	"syscall"
	"time"

	package transform

	import (
	"errors"
	"fmt"
	"strconv"
	"strings"

	"github.com/aws/aws-sdk-go/aws"
	"github.com/aws/aws-sdk-go/service/ecs"