Peter Mescalchin magnetikonline

DynamoDB local quick usage guide

Running a local version of DynamoDB inside a Docker container.

Commands

$ docker pull amazon/dynamodb-local:latest
$ docker run --publish 8000:8000 amazon/dynamodb-local

# in another terminal

Golang `io.TeeReader()` example

Opening a source words file.
Create a io.TeeReader(), writing read file chunks also to a gzip writer.
Output source chunks as read and total bytes.
Finally, output compressed bytes and total compressed size.

Output

$ go run main.go

GitHub token validation regular expressions

Regular expressions to check if a given GitHub token could be valid.

Personal access tokens (classic)
Fine-grained personal access tokens
GitHub Actions
Combined together

Personal access tokens (classic)

Backblaze B2 via rclone cheatsheet

Create B2 remote
Tasks
Reference

VirtualBox create host-only interface and attach

A host-only network interface is created virtually in software which appears to the host system.

This interface can be attached to one or more VMs, allowing connectivity between those VMs and communication between the host system and VMs.

Create & attach interface
Configure Ubuntu guests
- Ubuntu 18.04+
- Ubuntu pre 18.04

Git correct a commit via `--fixup`

Initial commit state:

$ git log --oneline
733e2ff Second widget done
fb2f677 First widget done
ac5db87 First commit

Modify DNS for Optus supplied Huawei B315 4G modem

The Huawei B315 modem supplied by Optus for the (now defunt) Vividwireless service is a workable but sadly rather crippled device, even down to the inability to modify assigned DNS servers from it's DHCP server away from Optus DNS to something sane (Google DNS/Cloudflare/etc.).

This script should allow for the easy update of assigned DNS servers and has been tested with Google Chrome.

Usage

Log into router web UI (e.g. http://192.168.0.1).
From the same browser session, open the "web developer tools" pane.

GitHub pull request toggle "force-pushed" events bookmarklet

Since November 2018, GitHub have started to display forced push events to pull request page timelines. This bookmarklet will toggle display of these events if they are getting in the way of meaningful commits.

Add the code below as the URL of a new bookmark:

javascript:((d)=>{if(d.getElementById('nuke-fp')==null){let e=d.createElement('style');e.id='nuke-fp';e.innerHTML='.nuke-fp{display:none}';d.getElementsByTagName('head')[0].appendChild(e)}for(let e of Array.from(d.querySelectorAll('.discussion-timeline .discussion-item-head_ref_force_pushed'))){e.classList.toggle('nuke-fp')}})(document)

Tested with Chrome 70.0.3538.102.

CIDR fit

Python function to determine if a given IPv4 CIDR fits into another.

How cidr_fit(cidr_a,cidr_b) works:

For both CIDR's given:
- Splits each CIDR into address and prefix size parts.
- Converts the address part to a 32 bit binary string.
  - Example: 192.168.0.1 becomes 11000000101010000000000000000001.

	'use strict';

	async function* delayList() {

	function delay(timeout) {

	return new Promise((resolve,reject) => {

	setTimeout(() => resolve(`dealyed for: ${timeout}ms`),timeout);
	});