packaging, ci: build the apk with the Crafter.Build Flatpak

Crafter.Build's releases carry a Flatpak and nothing else since
2026-10-02 (imsd a625248): the rolling `latest` release's
crafter-build-linux-x86_64-musl-v2.tar.gz that build-package.sh fetched
is gone, so the push of 0.2.6 failed at `fetch crafter-build` (run 10,
2026-10-14, three 404s) and published nothing; the registry still
serves 0.2.5.

The move imsd made on 2026-10-04: install the Flatpak
(net.catcrafts.CrafterBuild//stable from flatpak.catcrafts.net) in the
job container and run it as crafter-build. bubblewrap inside the
container needs a privileged runner, so the job runs on the `flatpak`
label. The host keeps clang and llvm-ar for libqcomtee, which
make-libqcomtee.sh compiles against the sysroot; the daemon's compiler,
lld and libc++ are the Flatpak's, so the host packages that served the
native test-suite run go. The sysroot gains llvm-runtimes, the package
with the std module source of its own libc++ (libc++-dev ships none),
added with --upgrade so a sysroot from before this change comes out
with a matching libc++ and source. The README's Build section carries
the install lines.

Tested: build-package.sh run end to end on this commit in a privileged
alpine:edge container (podman) on the workstation: crafter-build 2.1.0
(clang 23.1.2) from `stable`, the sysroot at libc++ and llvm-runtimes
23.1.3, daemon and agent cross-built, 8 suites passed natively, the
three apks built, the daemon an aarch64 PIE against the sysroot's musl
and libc++ (65 s). The rehearsed copy differs from this commit by the
wrapping of one comment line.

.forgejo/workflows/package.yml

@@ -7,9 +7,10 @@ name: package
 #
 # Build: crafter-build cross-compiles against an Alpine aarch64 sysroot
 # (packaging/build-package.sh — the README's "Cross-compiling" flow), the test
-# suite runs natively, and packaging/APKBUILD wraps the result. This needs no
-# privileged runner: it runs in an alpine:edge container on the ordinary
-# arch-latest runner.
+# suite runs natively, and packaging/APKBUILD wraps the result. crafter-build
+# is the Crafter.Build Flatpak, and bubblewrap inside the job container needs
+# a privileged runner: the job runs on the `flatpak` label (the Catcrafts
+# organisation's privileged runner), in an alpine:edge container.
 #
 # Release gating is the version: pkgver comes from interfaces/Fingerprintd.cppm,
 # the registry answers 409 for an already-published version, and the publish
@@ -27,7 +28,7 @@ on:
 
 jobs:
   package:
-    runs-on: arch-latest
+    runs-on: flatpak
     container:
       image: alpine:edge
     timeout-minutes: 90

README.md

@@ -10,7 +10,14 @@ that touches hardware.
 
 ## Build
 
+With the [Crafter Build](https://forgejo.catcrafts.net/Catcrafts/Crafter.Build)
+Flatpak, which carries the compiler:
+
 ```sh
+flatpak remote-add --if-not-exists flathub https://dl.flathub.org/repo/flathub.flatpakrepo
+flatpak remote-add --if-not-exists catcrafts https://flatpak.catcrafts.net/catcrafts.flatpakrepo
+flatpak install catcrafts net.catcrafts.CrafterBuild//stable
+alias crafter-build='flatpak run net.catcrafts.CrafterBuild//stable'
 crafter-build              # bin/fingerprintd-<target>-<march>/fingerprintd
 crafter-build test         # the unit suites
 ```

packaging/build-package.sh

@@ -5,44 +5,28 @@
 # (the README's "Cross-compiling" flow), run the test suite natively, and
 # package the result via packaging/APKBUILD. Expects an x86_64 Alpine
 # environment with root — the workflow runs it in an alpine:edge job
-# container on an ordinary runner. Root only installs packages and hands off
-# to a scratch user: the sysroot is built with apk.static --usermode (which
-# refuses root) and abuild wants a user too.
+# container on the privileged `flatpak` runner: crafter-build is the
+# Crafter.Build Flatpak, and bubblewrap inside the container needs the
+# privilege. Root only installs packages and hands off to a scratch user:
+# the sysroot is built with apk.static --usermode (which refuses root) and
+# abuild wants a user too.
 #
 # Built packages land in /home/build/.local/share/abuild/*/aarch64/fingerprintd*.apk;
 # the workflow's publish step uploads them to the Forgejo Alpine registry.
 
 set -eu
 
-# The musl build of crafter-build (Crafter.Build CI's release-musl job): this
-# container is Alpine, and the glibc launcher cannot run on musl. v2 = SSE4.2
-# baseline: the CI box is an Intel N5105 (no AVX). Overridable for local
-# rehearsals (file:// works).
-CRAFTER_URL=${CRAFTER_URL:-https://forgejo.catcrafts.net/Catcrafts/Crafter.Build/releases/download/latest/crafter-build-linux-x86_64-musl-v2.tar.gz}
+# crafter-build is the Crafter.Build Flatpak: it carries its own clang, lld
+# and libc++, and its SDK has glib, so nothing the daemon's build compiles
+# with is installed here. `stable` is the branch Crafter.Build publishes from
+# its release tags (`beta` follows every push to its master), so the
+# toolchain of a release moves only with a release of the toolchain. The
+# branch is overridable for a rehearsal against another one.
+CRAFTER_REMOTE=${CRAFTER_REMOTE:-https://flatpak.catcrafts.net/catcrafts.flatpakrepo}
+CRAFTER_REF=${CRAFTER_REF:-net.catcrafts.CrafterBuild//stable}
 
 SRC=$(CDPATH= cd -- "$(dirname "$0")/.." && pwd)
 
-# clang cross-targets aarch64 natively and the target's libc++/glib come from
-# the sysroot; llvm-runtimes/libc++-dev/glib-dev here serve the NATIVE
-# test-suite run. build-base = Alpine's standard build environment (the one
-# abuild implies): binutils' ld/ar for clang's default link driver, gcc's
-# libgcc_s/crt objects the musl clang driver links against.
-if [ "$(id -u)" = 0 ]; then
-	apk add -q git curl tar clang lld llvm llvm-runtimes libc++-dev llvm-libunwind-dev glib-dev \
-		build-base abuild sudo
-	id build >/dev/null 2>&1 || adduser -D build
-	addgroup build abuild 2>/dev/null || true
-	echo 'build ALL=(ALL) NOPASSWD: ALL' > /etc/sudoers.d/build
-	# abuild in cross mode strips with $CHOST-strip; llvm-strip handles any
-	# ELF arch, so give it that name
-	ln -sf "$(command -v llvm-strip)" /usr/local/bin/aarch64-alpine-linux-musl-strip
-	# the CI checkout arrives root-owned; crafter-build writes bin/ into it
-	chown -R build "$SRC"
-	# -l: a login shell, so HOME really is /home/build (abuild keys + output);
-	# it scrubs the environment, so carry the one knob that matters across
-	exec su -l build -c "CRAFTER_URL='${CRAFTER_URL:-}' sh -eu '$SRC/packaging/build-package.sh'"
-fi
-
 retry() { # retry <description> <cmd...>
 	_desc=$1; shift
 	for _i in 1 2 3; do
@@ -54,18 +38,43 @@ retry() { # retry <description> <cmd...>
 	return 1
 }
 
+# clang and llvm-ar here are for libqcomtee: make-libqcomtee.sh compiles it
+# with the host clang against the sysroot (C, objects and an archive, no
+# link). llvm also has llvm-strip, which abuild in cross mode strips with.
+if [ "$(id -u)" = 0 ]; then
+	apk add -q git curl tar flatpak clang llvm abuild sudo
+	# the Flatpak as a system installation the build user runs; its SDK
+	# (org.freedesktop.Sdk) comes from Flathub
+	flatpak remote-add --if-not-exists catcrafts "$CRAFTER_REMOTE"
+	flatpak remote-add --if-not-exists flathub https://dl.flathub.org/repo/flathub.flatpakrepo
+	retry "install crafter-build" flatpak install -y --noninteractive catcrafts "$CRAFTER_REF"
+	id build >/dev/null 2>&1 || adduser -D build
+	addgroup build abuild 2>/dev/null || true
+	echo 'build ALL=(ALL) NOPASSWD: ALL' > /etc/sudoers.d/build
+	# abuild in cross mode strips with $CHOST-strip; llvm-strip handles any
+	# ELF arch, so give it that name
+	ln -sf "$(command -v llvm-strip)" /usr/local/bin/aarch64-alpine-linux-musl-strip
+	# the CI checkout arrives root-owned; crafter-build writes bin/ into it
+	chown -R build "$SRC"
+	# -l: a login shell, so HOME really is /home/build (abuild keys + output);
+	# it scrubs the environment, so carry the one knob that matters across
+	exec su -l build -c "CRAFTER_REF='$CRAFTER_REF' sh -eu '$SRC/packaging/build-package.sh'"
+fi
+
 # interfaces/Fingerprintd.cppm is the version's single source of truth (same
 # derivation as make-bin-tarball.sh)
 VER=$(sed -n 's/.*Version = "\(.*\)".*/\1/p' "$SRC/interfaces/Fingerprintd.cppm")
 [ -n "$VER" ] || { echo "cannot read Version from interfaces/Fingerprintd.cppm" >&2; exit 1; }
 echo ">> packaging fingerprintd $VER"
 
-# --- crafter-build: static launcher from the rolling release
-mkdir -p "$HOME/crafter-build"
-retry "fetch crafter-build" \
-	sh -c "curl -fsSL '$CRAFTER_URL' | tar -xz -C '$HOME/crafter-build'"
-PATH="$HOME/crafter-build/bin:$PATH"
-export CRAFTER_BUILD_HOME="$HOME/crafter-build/share/crafter-build"
+# --- crafter-build: the Flatpak, under the name the rest of this file uses.
+# The build log names the build it ran with.
+mkdir -p "$HOME/bin"
+printf '#!/bin/sh\nexec flatpak run %s "$@"\n' "$CRAFTER_REF" > "$HOME/bin/crafter-build"
+chmod +x "$HOME/bin/crafter-build"
+PATH="$HOME/bin:$PATH"
+flatpak info "$CRAFTER_REF" | sed -n 's/^ *\(Version\|Commit\|Date\): */crafter-build \1: /p'
+crafter-build --version
 
 # --- aarch64 Alpine sysroot (unprivileged: apk.static --usermode)
 SYSROOT="$HOME/.cache/fingerprintd/sysroot-aarch64-alpine"

packaging/make-sysroot.sh

@@ -23,9 +23,14 @@ MIRROR="${MIRROR:-https://dl-cdn.alpinelinux.org/alpine/edge}"
 ARCH=aarch64
 # gcc is in the list for its crtbeginS.o/libgcc: clang's driver for
 # *-alpine-linux-musl links against the GCC runtime it detects under
-# <sysroot>/usr/lib/gcc/<triple>/.
+# <sysroot>/usr/lib/gcc/<triple>/. llvm-runtimes is in it for the std module
+# source of this very libc++ (usr/share/libc++/v1/std.cppm; libc++-dev ships
+# none): crafter-build compiles the sysroot's own copy first. --upgrade below
+# is for a run over an existing sysroot: added alone beside an older libc++,
+# a newer llvm-runtimes' source does not compile against its headers
+# (imsd, 2026-10-04: 23.1.2 against 22.1.8); upgraded together, it does.
 # glib-dev is for the GDBus bus layer (net.reactivated.Fprint).
-PKGS="musl-dev libc++ libc++-dev glib-dev compiler-rt llvm-libunwind-dev gcc"
+PKGS="musl-dev libc++ libc++-dev llvm-runtimes glib-dev compiler-rt llvm-libunwind-dev gcc"
 
 work=$(mktemp -d)
 trap 'rm -rf "$work"' EXIT
@@ -48,6 +53,6 @@ mkdir -p "$SYSROOT"
     --arch "$ARCH" --root "$SYSROOT" --initdb --no-scripts --no-cache \
     --usermode --keys-dir "$work/usr/share/apk/keys/$ARCH" \
     -X "$MIRROR/main" -X "$MIRROR/community" \
-    add $PKGS
+    add --upgrade $PKGS
 
 echo ">> done: $SYSROOT"