Add example extensions built with flix.sh and flatwrap.sh (#186)

To show how flix.sh and flatwrap.sh can be used to ship regular Linux
packages as sysext we can add two examples.
As flix example include an extension for the tilde text editor from
Debian and as flatwrap example include an extension for btop from
Alpine (originally I used htop but we might ship this in Flatcar later
by default - note that you need to set LANG=en_US.UTF-8 or run with btop
with --utf-force on Flatcar).


## How to use/Testing done

`./bakery.sh create --sysupdate false btop 1.4.0` and `./bakery.sh
create --sysupdate false tilde 1.1.2` with copying the extension to a
Flatcar VM.

Author: pothos

btop.sysext/create.sh

@@ -0,0 +1,40 @@
+#!/usr/bin/env bash
+# vim: et ts=2 syn=bash
+#
+# btop sysext.
+#
+
+RELOAD_SERVICES_ON_MERGE="false"
+
+function list_available_versions() {
+  # Add sort for consuming all curl output
+  # (When copying this, you might need to switch to 'main' from 'community')
+  curl -sSfL https://dl-cdn.alpinelinux.org/alpine/latest-stable/community/x86_64/ | { sort || true ; } | grep -m1 -o "btop-.*apk" | cut -d - -f 2
+}
+# --
+
+function populate_sysext_root() {
+  local sysextroot="$1"
+  local arch="$2"
+  local version="$3"
+
+  local img_arch="$(arch_transform 'x86-64' 'amd64' "$arch")"
+  img_arch="$(arch_transform 'arm64' 'arm64/v8' "$img_arch")"
+
+  docker run --rm \
+              -i \
+              -v "${scriptroot}/tools/":/tools \
+              -v "${sysextroot}":/install_root \
+              --platform "linux/${img_arch}" \
+              --pull always \
+              --network host \
+              docker.io/alpine:latest \
+                  sh -c "apk add -U btop bash coreutils grep && cd /install_root && ETCMAP=chroot /tools/flatwrap.sh / btop /usr/bin/btop"
+  # Alpine has /etc/terminfo instead of /usr/terminfo,
+  # so above we need to skip mapping the host /etc into the flatwrap env
+  mv "${sysextroot}"/btop/usr "${sysextroot}"/usr
+  rmdir "${sysextroot}"/btop
+  # Workaround: The bakery.sh tmp dir cleanup fails otherwise
+  chmod -R u+w "${sysextroot}" || true
+}
+# --

btop.sysext/test.sh

@@ -92,3 +92,9 @@ cilium latest
 
 bird 3.1.2
 bird latest
+
+btop 1.4.0
+btop latest
+
+tilde 1.1.2
+tilde latest

release_build_versions.txt

@@ -0,0 +1,43 @@
+#!/usr/bin/env bash
+# vim: et ts=2 syn=bash
+#
+# tilde sysext.
+#
+
+RELOAD_SERVICES_ON_MERGE="false"
+
+function list_available_versions() {
+  # Add sort for consuming all curl output
+  curl -sSfL https://packages.debian.org/bookworm/tilde | { sort || true ; } | grep -m1 -o "tilde_.*dsc" | cut -d _ -f 2 | cut -d - -f 1
+}
+# --
+
+function populate_sysext_root() {
+  local sysextroot="$1"
+  local arch="$2"
+  local version="$3"
+
+  local img_arch="$(arch_transform 'x86-64' 'amd64' "$arch")"
+  img_arch="$(arch_transform 'arm64' 'arm64/v8' "$img_arch")"
+  img_arch="$(arch_transform 'aarch64' 'arm64/v8' "$img_arch")"
+
+  local lib_arch="$(arch_transform 'amd64' 'x86_64' "$arch")"
+  lib_arch="$(arch_transform 'x86-64' 'x86_64' "$lib_arch")"
+  lib_arch="$(arch_transform 'arm64' 'aarch64' "$lib_arch")"
+
+  docker run --rm \
+              -i \
+              -v "${scriptroot}/tools/":/tools \
+              -v "${sysextroot}":/install_root \
+              --platform "linux/${img_arch}" \
+              --pull always \
+              --network host \
+              docker.io/debian:bookworm-slim \
+                  sh -c "apt update && apt install -y tilde patchelf && cd /install_root && /tools/flix.sh / tilde /usr/bin/tilde /usr/lib/${lib_arch}-linux-gnu/transcript1 /usr/lib/${lib_arch}-linux-gnu/libt3widget"
+  # We ship /usr/lib/...-linux-gnu/{transcript1,libt3widget} host folders.
+  # But we assume that the host has /usr/share/terminfo around
+  # otherwise we would need to add it as last argument above.
+  mv "${sysextroot}"/tilde/usr "${sysextroot}"/usr
+  rmdir "${sysextroot}"/tilde
+}
+# --