jeremiehuchet

This note explain how to reduce a mounted filesystem on an LVM partition. It requires a reboot but most of the operations can be done online and the system can be used during the operations.

1. Remount filesystem read-only

sudo mount -f -o remount,ro /home

2. Snapshot the volume hosting the filesystem

sudo lvcreate -s data/home -L 30G -n home_resize
sudo lvdisplay data/home_resize                 

jeremiehuchet

shelly-ha-mqtt-auto-discovery

A Shelly script to install on Shelly devices to publish MQTT announcement messages for Home Assistant.

![Example screenshot](https://gist.githubusercontent.com/jeremiehuchet/84e8dc96573e37200c2ab3bd4e013729/raw/793e171ba74eb5c3f39e5f58d18b648ba9b16659/screenshot.png

jeremiehuchet

#!/usr/bin/env bash
set -e

# see https://techdocs.akamai.com/iot-token-access-control/reference/generate-jwt-rsa-keys

PRIVATE_KEY_PEM="$1"

b64encode() {
  echo -n "$*" | base64 -w 0 | sed s/\+/-/ | sed -E s/=+$//
}

jeremiehuchet

#!/bin/bash

# setup wifi
wpa_supplicant -B -i interface -c <(wpa_passphrase 'SSID' 'key')

# partition disks
# sda1 /boot
# sda2 LVM PV
#   - vg hdd
#      - lv root

jeremiehuchet

{ pkgs }:

{
  # fetch docker image content and return path in nix store
  # inspired from https://github.com/NixOS/nixpkgs/blob/6dab1b50a63fa6e9dfb9bd9eddd3f5d5c7b055ef/pkgs/build-support/docker/default.nix#L264
  fetchDocker = coordinates:
    let
      name = "${coordinates.finalImageName}-${coordinates.finalImageTag}";
      result = pkgs.dockerTools.runWithOverlay {
        name = "docker-exporter-${name}";

jeremiehuchet

HP DeskJet Pro 9600

In /etc/nixos/configuration.nix:

services.printing.enable = true;
services.printing.drivers = [ pkgs.hplip ];
services.printing.startWhenNeeded = true; # optional

users.users..extraGroups = [ ... "lp" ... ];

jeremiehuchet

#!/bin/sh -e

if [[ $# -ne 1 ]] ; then
  cat - <<HELP
usage: $0 <gpg secret key id>

Generates a printable PDF file <gpg secret key id>-backup.pdf for the given key id.
HELP
  exit 1
fi

jeremiehuchet

// get the original destination for the socket when redirect by linux iptables 
// refer to https://raw.githubusercontent.com/missdeer/avege/master/src/inbound/redir/redir_iptables.go
//
const (
	SO_ORIGINAL_DST      = 80
	IP6T_SO_ORIGINAL_DST = 80
)

func getOriginalDst(clientConn *net.TCPConn) (rawaddr []byte, host string, newTCPConn *net.TCPConn, err error) {
	if clientConn == nil {