Instructions to use sdm inside a Docker container

Docs/Using-Docker.md

@@ -1,10 +1,60 @@
 # Using Docker
 
-sdm does not currently work with Docker.
+sdm can work from within a Docker container.
 
-If you are interested in seeing this work, AND are fairly Docker-enlightened, please consider providing me with a "sdm on Docker" cookbook that an unenlightened Docker user like me can follow.
+Some reasons to do this are:
+- reliable and repeatable image creation (much in the spirit of sdm)
+- one might dislike the dependencies of sdm (e.g. as installed by EZsdmInstaller)
+- one might dislike to run so many "scary" (e.g. fdisk, ...) commands as root on important systems
+- one might dislike to run shell scripts freshly downloaded from the Internet (in particular as root)
 
-Once such a guide is provided and I am able to verify that it works, I'll include it in the sdm Documentation.
+But in order to function, sdm still needs elevated permissions (e.g. for losetup and mount calls), so the `--priviledged` flag to docker is required. That flag means the docker container can protect against mistakes by the sdm developers, but won't prevent malicious attacks.
+
+First (after making sure that `sudo docker run hello-world` does work well), create a script `myscript.sh` that you want to run inside the container:
+
+```
+#!/bin/bash
+
+# prepare the environment and download sdm
+export DEBIAN_FRONTEND=noninteractive
+apt-get update
+apt-get --yes install fdisk git file binfmt-support systemd binfmt-support gdisk keyboard-configuration parted qemu-user-static rsync systemd-container uuid
+git clone https://github.com/gitbls/sdm
+
+# customize the image. Probably add many more --plugin lines here
+sdm/sdm --customize --sdmdir /root/sdm \
+  --plugin sshd:"password-authentication=no" \
+  --plugin disables:piwiz \
+  /root/sdm_working_dir/2024-11-19-raspios-bookworm-armhf-lite.img
+
+# burn the image
+sdm/sdm --sdmdir /root/sdm \
+  --burnfile /root/sdm_working_dir/burned.img \
+  --host somepi \
+  /root/sdm_working_dir/2024-11-19-raspios-bookworm-armhf-lite.img
+```
+
+See <a href="Example-Burn-Multiple-Hosts-From-Single-IMG.md">Example-Burn-Multiple-Hosts-From-Single-IMG</a> for an idea how to burn many images in one loop.
+
+Second, prepare a directory to inject into the container:
+```
+mkdir working_dir
+cd working_dir
+wget https://downloads.raspberrypi.com/raspios_lite_armhf/images/raspios_lite_armhf-2024-11-19/2024-11-19-raspios-bookworm-armhf-lite.img.xz
+unxz 2024-11-19-raspios-bookworm-armhf-lite.img.xz
+cd ..
+```
+
+Third, execute!
+
+```
+sudo docker run --privileged --network host --rm \
+  -v "$(pwd)/myscript.sh:/myscript.sh" \
+  -v "$(pwd)/working_dir:/root/sdm_working_dir" \
+  --device=/dev/loop-control \
+  --device=/dev/loop0 \
+   debian:latest bash /myscript.sh
+```
 
 <br>
 <form>