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.

13 files changed, 28 insertions, 18 deletions

diff --git a/.github/dependabot.yml b/.github/dependabot.yml
index 3e067c176f..54593c50f7 100644
--- a/.github/dependabot.yml
+++ b/.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
diff --git a/.gitmodules b/.gitmodules
new file mode 100644
index 0000000000..c69576e9bb
--- /dev/null
+++ b/.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
diff --git a/mkosi.images/base/mkosi.conf.d/10-arch/mkosi.conf b/mkosi.images/base/mkosi.conf.d/10-arch/mkosi.conf
index 75dbbb2dde..9cb45cc954 100644
--- a/mkosi.images/base/mkosi.conf.d/10-arch/mkosi.conf
+++ b/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"
 
diff --git a/mkosi.images/base/mkosi.conf.d/10-centos/mkosi.conf b/mkosi.images/base/mkosi.conf.d/10-centos/mkosi.conf
index 607c2d2daf..0f57319c2a 100644
--- a/mkosi.images/base/mkosi.conf.d/10-centos/mkosi.conf
+++ b/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=
diff --git a/mkosi.images/base/mkosi.conf.d/10-debian-ubuntu/mkosi.conf b/mkosi.images/base/mkosi.conf.d/10-debian-ubuntu/mkosi.conf
index f6fc43a848..47f3b7f488 100644
--- a/mkosi.images/base/mkosi.conf.d/10-debian-ubuntu/mkosi.conf
+++ b/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
diff --git a/mkosi.images/base/mkosi.conf.d/10-fedora/mkosi.conf b/mkosi.images/base/mkosi.conf.d/10-fedora/mkosi.conf
index 1424709cef..a0b9f6f0fe 100644
--- a/mkosi.images/base/mkosi.conf.d/10-fedora/mkosi.conf
+++ b/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=
diff --git a/mkosi.images/base/mkosi.conf.d/10-opensuse/mkosi.conf b/mkosi.images/base/mkosi.conf.d/10-opensuse/mkosi.conf
index 1fca47b7cb..63498c5098 100644
--- a/mkosi.images/base/mkosi.conf.d/10-opensuse/mkosi.conf
+++ b/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
diff --git a/mkosi.images/base/mkosi.sync b/mkosi.images/base/mkosi.sync
index b95a73bc08..72b5cf7c33 100755
--- a/mkosi.images/base/mkosi.sync
+++ b/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
diff --git a/pkg/arch b/pkg/arch
new file mode 160000
+Subproject 733045c8f6b0acf2f0cfaac207500483a678f4d
diff --git a/pkg/centos b/pkg/centos
new file mode 160000
+Subproject 3cf45106c8bc5a050901851be6b2ac85b6f5c57
diff --git a/pkg/debian b/pkg/debian
new file mode 160000
+Subproject 49132a870dfe281e1973a8c44acffb87a1db533
diff --git a/pkg/fedora b/pkg/fedora
new file mode 160000
+Subproject 2822a03dded26b9453bddbba7c6a152de8204ae
diff --git a/pkg/opensuse b/pkg/opensuse
new file mode 160000
+Subproject 37aca188c2ef606319217b30ff8b0c66df6c60f