mkosi: Introduce packaging sources as submodules

By always cloning the latest branch commit, we can't bisect properly
using mkosi as when bisecting wildly different packaging sources will
be used compared to when the commit was merged. By using submodules, we
track individual commits which means when bisecting the same packaging
sources will be used.

We use git submodules as dependabot has support for automatically making
PRs to update git submodules. This commit also includes the necessary
dependabot configuration to enable this.

We make ubuntu/debian use the same submodule instead of adding the debian
packaging sources twice by introducing a new $PKG_SUBDIR environment variable
and using it instead of $DISTRIBUTION.

.github/dependabot.yml

@@ -17,3 +17,8 @@ updates:
     schedule:
       interval: "monthly"
     open-pull-requests-limit: 2
+  - package-ecosystem: "gitsubmodule"
+    directory: "/"
+    schedule:
+      interval: "daily"
+    open-pull-requests-limit: 2

.gitmodules

@@ -0,0 +1,20 @@
+[submodule "pkg/fedora"]
+	path = pkg/fedora
+	url = https://src.fedoraproject.org/rpms/systemd
+	branch = rawhide
+[submodule "pkg/opensuse"]
+	path = pkg/opensuse
+	url = https://code.opensuse.org/package/systemd
+	branch = master
+[submodule "pkg/debian"]
+	path = pkg/debian
+	url = https://salsa.debian.org/systemd-team/systemd
+	branch = debian/master
+[submodule "pkg/centos"]
+	path = pkg/centos
+	url = https://git.centos.org/rpms/systemd
+	branch = c9s-sig-hyperscale
+[submodule "pkg/arch"]
+	path = pkg/arch
+	url = https://gitlab.archlinux.org/daandemeyer/systemd
+	branch = strip

mkosi.images/base/mkosi.conf.d/10-arch/mkosi.conf

@@ -10,8 +10,6 @@ InitrdInclude=initrd/
 # https://gitlab.archlinux.org/archlinux/packaging/packages/systemd/-/merge_requests/8 is merged.
 [Content]
 Environment=
-        PKG_URL="https://gitlab.archlinux.org/daandemeyer/systemd"
-        PKG_BRANCH="strip"
         PKG_SUBDIR="arch"
         SYSTEMD_PACKAGES="systemd systemd-ukify systemd-sysvcompat systemd-resolvconf"
 

mkosi.images/base/mkosi.conf.d/10-centos/mkosi.conf

@@ -5,8 +5,6 @@ Distribution=centos
 
 [Content]
 Environment=
-        PKG_URL="https://git.centos.org/rpms/systemd"
-        PKG_BRANCH="c9s-sig-hyperscale"
         PKG_SUBDIR="centos"
 
 Packages=

mkosi.images/base/mkosi.conf.d/10-debian-ubuntu/mkosi.conf

@@ -9,8 +9,6 @@ InitrdInclude=initrd/
 
 [Content]
 Environment=
-        PKG_URL="https://salsa.debian.org/systemd-team/systemd"
-        PKG_BRANCH="debian/master"
         PKG_SUBDIR="debian"
         SYSTEMD_PACKAGES="systemd
                           systemd-userdbd

mkosi.images/base/mkosi.conf.d/10-fedora/mkosi.conf

@@ -5,8 +5,6 @@ Distribution=fedora
 
 [Content]
 Environment=
-        PKG_URL="https://src.fedoraproject.org/rpms/systemd"
-        PKG_BRANCH="rawhide"
         PKG_SUBDIR="fedora"
 
 Packages=

mkosi.images/base/mkosi.conf.d/10-opensuse/mkosi.conf

@@ -8,8 +8,6 @@ InitrdInclude=initrd/
 
 [Content]
 Environment=
-        PKG_URL="https://code.opensuse.org/package/systemd"
-        PKG_BRANCH="master"
         PKG_SUBDIR="opensuse"
         SYSTEMD_PACKAGES="systemd
                           udev

mkosi.images/base/mkosi.sync

@@ -2,12 +2,7 @@
 # SPDX-License-Identifier: LGPL-2.1-or-later
 set -e
 
-if ((CACHED)); then
-    exit 0
-fi
-
-if [ -z "$(ls --almost-all "pkg/$PKG_SUBDIR")" ]; then
-    git clone "$PKG_URL" --branch "$PKG_BRANCH" "pkg/$PKG_SUBDIR"
-elif [ -d "pkg/$PKG_SUBDIR/.git" ] && [ "$(git -C "pkg/$PKG_SUBDIR" rev-parse --abbrev-ref HEAD)" = "$PKG_BRANCH" ]; then
-    git -C "pkg/$PKG_SUBDIR" pull
+if [ -z "$(ls --almost-all "pkg/$PKG_SUBDIR")" ] || [ -f "pkg/$PKG_SUBDIR/.git" ]; then
+    git submodule sync "pkg/$PKG_SUBDIR"
+    git submodule update --init "pkg/$PKG_SUBDIR"
 fi

pkg/arch

@@ -0,0 +1 @@
+Subproject commit 733045c8f6b0acf2f0cfaac207500483a678f4d2

pkg/centos

@@ -0,0 +1 @@
+Subproject commit 3cf45106c8bc5a050901851be6b2ac85b6f5c571

pkg/debian

@@ -0,0 +1 @@
+Subproject commit 49132a870dfe281e1973a8c44acffb87a1db5336

pkg/fedora

@@ -0,0 +1 @@
+Subproject commit 2822a03dded26b9453bddbba7c6a152de8204aec

pkg/opensuse

@@ -0,0 +1 @@
+Subproject commit 37aca188c2ef606319217b30ff8b0c66df6c60f1