add /kitchen-kiosk, a short writeup of Hob's UI

2 files changed, 88 insertions, 0 deletions

diff --git a/src/kitchen-kiosk.thrust b/src/kitchen-kiosk.thrust
new file mode 100644
index 0000000..53de7a6
--- /dev/null
+++ b/src/kitchen-kiosk.thrust
@@ -0,0 +1,87 @@
+---
+title: a kiosk for my kitchen
+date: 2020-08-05
+---
+{% extends 'templates/base.html' %}
+{% block body %}
+	<nav>
+		<a href='/projects'>&gt; projects</a>
+	</nav>
+
+	<header>
+		<h1>{{ title }}</h1>
+	</header>
+
+	<article>
+	{% markdown %}
+
+	In a corner of my kitchen, there is a little touchscreen interface for "kitchen things".
+	Below is why I have that, what it's made of, and how it works.
+
+	## Why?
+
+	There are two main reasons why I want a kitchen kiosk unit:
+
+	- I have too Internet of Things things in my kitchen, and getting my phone out to control it is annoying.
+	- I want to record when I drink coffee, when I snack, etc, and getting my phone out to log that is annoying.
+
+	## What?
+
+	I already have a Raspberry Pi in the Kitchen to provide [WiFi](/wifi) and [audio](/multi-room-audio), so extending that is a good start.
+	I could create a custom control panel with physical buttons, but adding a touchscreen to an existing unit is easier.
+
+	So I got the official Raspberry Pi touchscreen, a stand for the screen, and voila, the hardware side is done.
+
+	## How?
+
+	Continuing with the theme of minimal effort for maximum gain, I decided to use my existing skills and implement the UI with a website:
+
+	- I can hack up a webserver pretty fast.
+	- Chromium has a kiosk mode.
+	- Chromium can handle rendering and input.
+
+	This means that all I need to do is make Chromium start on boot, and write a simple webserver!
+
+	From a standard Raspbian image, install the relevant softwares:
+
+		$ sudo apt install chromium lightdm xinput
+
+	Then, create a user to run Chromium, here called `kiosk`:
+
+		$ sudo adduser kiosk
+
+	Next, we're going to use `lightdm` to bring up Xorg and automatically log in as `kiosk`:
+
+		$ cat /etc/lightdm/lightdm.conf
+		[Seat:seat0]
+		type=local
+		pam-service=lightdm-autologin
+		autologin-user=kiosk
+		autologin-user-timeout=0
+		xserver-command = X -nocursor
+
+	For our `kiosk` user to set the brightness, we need to add a `udev` rule to make it writeable:
+
+		$ cat /etc/udev/rules.d/50-backlight.rules 
+		SUBSYSTEM=="backlight",RUN+="/bin/chmod 666 /sys/class/backlight/%k/brightness /sys/class/backlight/%k/bl_power"
+
+	Finally, `kiosk`'s graphical login script (`~/.xsession`) will set the brightness and display-sleep modes, then start Chromium:
+
+		$ cat /home/kiosk/.xsession
+		readonly standby_seconds=60
+		readonly suspend_seconds=60
+		readonly off_seconds=60
+
+		readonly brightness_percent=50
+
+		# TODO: write a custom UI webserver.
+		readonly website="https://ethulhu.co.uk"
+
+		xset dpms "${standby_seconds}" "${suspend_seconds}" "${off_seconds}"
+		echo "${brightness_percent}" > /sys/class/backlight/rpi_backlight/brightness
+		exec chromium --noerrdialogs --kiosk --incognito "${website}"
+
+	Reboot the Raspberry Pi, and it should automatically log in as `kiosk` and run the website.
+	{% endmarkdown %}
+	</article>
+{% endblock %}
diff --git a/src/projects.thrust b/src/projects.thrust
index af8d5c6..7a52892 100644
--- a/src/projects.thrust
+++ b/src/projects.thrust
@@ -23,5 +23,6 @@ subtitle: may or may not also be art
 	- Simplifying services and sandboxing Steam with [systemd Dynamic Users](/systemd-dynamicuser).
 	- Using [YubiKeys](/yubikey) to improve my online security and convenience.
 	- Using [Nix and NixOS](/nixos) for pure-functional and repeatable infrastructure.
+	- Creating a [Kitchen Kiosk](/kitchen-kiosk) to be a kiosk in my kitchen.
 	{% endmarkdown %}
 {% endblock %}