Thanks to visit codestin.com
Credit goes to gist.github.com

Skip to content

Instantly share code, notes, and snippets.

View davidar's full-sized avatar

David A Roberts davidar

354 followers · 57 following
View GitHub Profile
@davidar
davidar / playwright-mcp-flatpak-chrome.md
Created May 23, 2026 01:42
Playwright MCP with Flatpak Chrome on Linux (real GPU / WebGPU)

Playwright MCP with Flatpak Chrome on Linux (real GPU / WebGPU)

How to run Playwright MCP against the Flatpak build of Chrome on Linux, with the real GPU enabled so WebGPU / WebGL hit your discrete GPU instead of SwiftShader.

Assumes you've already got WebGPU working in Flatpak Chrome (the chrome-flags.conf part). This gist is about getting Playwright MCP to drive that same Chrome with the real GPU enabled.

1. Make Playwright find Flatpak Chrome

Playwright MCP defaults to the chrome channel and hardcodes the path /opt/google/chrome/chrome. Symlink that to the Flatpak export (which is itself a shell script that does exec /usr/bin/flatpak run … com.google.Chrome "$@"):

@davidar
davidar / docker-healthcheck-blind-spots.md
Last active April 11, 2026 00:54
Docker healthchecks can't detect host-side network failures — why and what to do instead

Docker Healthchecks Can't Detect Host-Side Network Failures

If you're using Docker healthchecks with an autoheal sidecar (like willfarrell/autoheal) to auto-restart unhealthy containers, there's a class of failures they'll never catch.

The Setup

A common pattern for self-healing containers:

services:
@davidar
davidar / ipv6-only-docker-hetzner.md
Last active April 11, 2026 00:54
Running Docker on an IPv6-only Hetzner VPS — full setup guide

Running Docker on an IPv6-Only VPS (Hetzner)

Hetzner's cheapest VPS plans come with IPv6-only connectivity. Docker doesn't handle this well out of the box — containers won't be able to reach the internet. Here's the full setup.

The Problem

Docker defaults to IPv4 networking. On an IPv6-only host, containers can't resolve DNS or reach external services (package registries, APIs, OAuth providers, etc.). You'll see:

  • apt-get update failing inside containers
  • API calls timing out
@davidar
davidar / tailscale-exit-node-breaks-docker.md
Created April 11, 2026 00:51
Tailscale exit node breaks Docker localhost access — diagnosis and fix with systemd timer

Tailscale Exit Node Breaks Docker Localhost Access (and How to Fix It)

If you're running Tailscale with an exit node (e.g. Mullvad) on a server that also runs Docker containers, you may hit a maddening issue: containers appear healthy but are unreachable from the host.

Symptoms

  • curl http://127.0.0.1:<port> to a Docker container hangs (TCP connects, but HTTP times out)
  • docker exec into the container and curling localhost works fine
  • Docker healthchecks pass
  • Restarting Docker or Tailscale sometimes fixes it temporarily
@davidar
davidar / earlyoom-desktop-linux.md
Created February 22, 2026 04:32
earlyoom configuration for desktop Linux — swap-aware OOM prevention with process targeting

earlyoom for Desktop Linux

The default kernel OOM killer reacts too late for desktop use — by the time it fires, the system is deep in swap thrash and unresponsive. systemd-oomd is better but still too conservative for desktops with lots of browser tabs.

earlyoom monitors memory and swap usage and kills processes before the system becomes unusable.

Install

# Fedora / rpm-ostree
@davidar
davidar / nvidia-hybrid-gpu-power-management.md
Created February 22, 2026 04:30
Fix slow Flatpak/app launches on NVIDIA hybrid laptops caused by GPU D3 sleep wake latency

Fix Slow App Launches on NVIDIA Hybrid Laptops (GPU D3 Sleep)

Problem

Apps (especially Flatpaks) take ~2 seconds to launch because the NVIDIA dGPU enters D3 power state when idle. Waking from D3 adds ~2 seconds of latency to any GPU operation.

This affects hybrid laptops (NVIDIA + AMD/Intel iGPU) where the kernel's runtime power management suspends the dGPU.

Solution

@davidar
davidar / dropbox-flatpak-cli-fix.md
Created February 22, 2026 04:28
Fix Dropbox CLI (dropbox.py) not detecting the Flatpak Dropbox daemon

Fix Dropbox CLI with Flatpak Dropbox

Problem

The official Dropbox CLI (dropbox.py) doesn't detect the Flatpak Dropbox daemon. Commands like dropbox status report "Dropbox isn't running" even when it is.

Root cause: The CLI checks ~/.dropbox/dropbox.pid, but the Flatpak daemon writes its sandboxed PID there, which doesn't correspond to a real process on the host.

Fix

@davidar
davidar / goodix-fingerprint-fedora-atomic.md
Created February 22, 2026 04:26
Fix Goodix fingerprint scanner (27c6:550a) on Fedora Atomic (Silverblue, Bluefin, etc.) with PAM timeout fix

Goodix Fingerprint Scanner on Fedora Atomic (Silverblue, Bluefin, etc.)

Tested with Goodix 27c6:550a on Fedora 43 (Bluefin DX, nvidia-open). Should work for other Goodix TOD-compatible readers.

Install the Driver

The Goodix driver requires libfprint-tod, which replaces the base libfprint package.

# Add the COPR repo (uses $releasever automatically)
@davidar
davidar / qt-flatpak-dark-mode-gnome.md
Created February 15, 2026 06:47
Qt Flatpak apps don't detect dark mode on GNOME — root cause analysis and workaround

Qt Flatpak Apps Don't Detect Dark Mode on GNOME

TL;DR: Qt6 Flatpak apps using the KDE runtime ignore GNOME's dark mode preference. The workaround is three environment variables + Kvantum.

The Problem

If you run Qt/KDE Flatpak apps (qBittorrent, OBS Studio, VLC, etc.) on GNOME with dark mode enabled, they render with a light theme — white backgrounds, light widgets, the works.

This is caused by two bugs in the Qt/KDE stack.

@davidar
davidar / enable-webgpu-flatpak-chrome.md
Created December 28, 2025 12:55
Enable WebGPU on Flatpak Chrome (Linux)

Enable WebGPU on Flatpak Chrome (Linux)

WebGPU isn't enabled by default on Linux Chrome. Here's how to enable it for Flatpak Chrome.

Quick Setup

Create the config file at ~/.var/app/com.google.Chrome/config/chrome-flags.conf with these contents:

--enable-unsafe-webgpu