build: change approach to versioning

Currently, we choose the version number that we use at the time that
./autogen.sh is first run.  That means that if you configure your tree
and hack on it for a while, making commits as you go, the
overly-specific version number will soon be out of date.  This version
number is the number used when building tarballs for testing.  Even
switching to old branches on previous versions can result in the version
number not being updated.

Let's move to automake's suggested approach[1] to dynamic versioning by
introducing a `version.m4` file.  We write that file from two places:

 - `./autogen.sh` writes an approximate version number (the last release)
   appended by +git (eg. "270+git")

 - from `make dist` we write the value we find in `$(VERSION)` and call
   autoreconf to update the configure script accordingly

The expectation is now that anyone who calls `make dist` should specify
the VERSION explicitly.  That's two places:

 - from `tools/make-dist` we specify the full `git describe` style
   version

 - from the release workflow we specify the tag name

Since the only thing that uses `make dump-dist` anymore is
`tools/make-dist`, and since it now provides its own version number, we
can drop the rule and print the filename directly.

Since we move to `version.m4`-style versioning, our tarballs will no
longer contain the `.tarball` file.

Finally, since we're going to end up having more tarballs created, with
various version numbers, add `cockpit-*.tar.xz` to `CLEANFILES` to help
keep things under control.

[1] https://www.gnu.org/software/automake/manual/html_node/Rebuilding.html

.github/workflows/release.yml

@@ -28,7 +28,7 @@ jobs:
         run: ./autogen.sh
 
       - name: Build release
-        run: make dist -j$(nproc)
+        run: make dist -j$(nproc) VERSION='${{ github.ref_name }}'
 
       - id: publish
         name: Publish GitHub release

Makefile.am

@@ -15,6 +15,7 @@ sbin_PROGRAMS =
 #  make dist
 
 EXTRA_DIST = README.md
+CLEANFILES += cockpit-*.tar.xz
 
 # We override distdir for two reasons:
 #  - we need to make sure DISTFILES is built before calling `make distdir-am`
@@ -26,11 +27,20 @@ distdir: $(DISTFILES)
 		git -C '$(srcdir)' ls-files -x test/reference test tools > .extra_dist.tmp && \
 		mv .extra_dist.tmp '$(srcdir)/.extra_dist'; fi
 	$(MAKE) $(AM_MAKEFLAGS) distdir-am EXTRA_FILES="$$(tr '\n' ' ' < $(srcdir)/.extra_dist) .extra_dist"
-	echo $(VERSION) > $(distdir)/.tarball
 	$(srcdir)/src/client/add-metainfo-releases --version '$(VERSION)' '$(distdir)'/src/client/*.metainfo.xml
 	$(srcdir)/tools/adjust-distdir-timestamps "$(distdir)"
 	@echo '  DIST     $(DIST_ARCHIVES)'
 
+# Needed to ensure the tarball is correct for $(VERSION) override
+$(distdir)/version.m4: FORCE
+	@rm -f $(distdir)/version.m4
+	$(AM_V_GEN) echo 'm4_define(VERSION_NUMBER, [$(VERSION)])' > $@
+
+dist-hook: $(distdir)/configure
+$(distdir)/configure: $(distdir)/version.m4
+	@rm -f $(distdir)/configure
+	$(AM_V_GEN) autoreconf $(distdir)
+
 # Various downstream packaging assets
 dist-hook: $(distdir)/tools/arch/PKGBUILD
 $(distdir)/tools/arch/PKGBUILD: $(distdir)/tools/arch/PKGBUILD.in
@@ -53,9 +63,6 @@ DISTCHECK_CONFIGURE_FLAGS = --enable-prefix-only
 distcheck-hook:
 	$(srcdir)/tools/check-dist $(distdir)
 
-dump-dist:
-	@echo "$(abs_builddir)/$(distdir).tar.xz"
-
 # -----------------------------------------------------------------------------
 
 TESTS = \

autogen.sh

@@ -4,7 +4,12 @@ set -eu
 
 srcdir="${0%/*}"
 
-(cd "${srcdir}" && autoreconf -is --warnings obsolete)
+(
+    cd "${srcdir}"
+    echo "m4_define(VERSION_NUMBER, [$(git describe --tags --abbrev=0)+git])" > version.m4
+    autoreconf -is --warnings obsolete
+)
+
 [ -n "${NOCONFIGURE:-}" ] && exit
 
 case "${1:-}" in

configure.ac

@@ -15,22 +15,13 @@
 # You should have received a copy of the GNU Lesser General Public License
 # along with Cockpit; If not, see <http://www.gnu.org/licenses/>.
 
+m4_include([version.m4])
 AC_INIT([Cockpit],
-        [m4_esyscmd_s([if [ -f .tarball ]; then cat .tarball; else echo $(git describe | tr - . ); fi])],
+        [VERSION_NUMBER],
         [devel@lists.cockpit-project.org],
         [cockpit],
         [https://cockpit-project.org/])
 
-# The above command needs to run in a git repository or `.tarball` file needs to be
-# present. If that didn't work bail early. Cockpit needs to know its own version number
-AC_MSG_CHECKING(that PACKAGE_VERSION is properly set)
-if test -z "$PACKAGE_VERSION"; then
-  AC_MSG_RESULT(no)
-  AC_MSG_ERROR(Please build from a .git checkout or .tar.xz tarball)
-else
-  AC_MSG_RESULT(yes)
-fi
-
 AC_CONFIG_SRCDIR([src])
 AC_CONFIG_HEADERS([config.h])
 AC_CONFIG_AUX_DIR([tools])

tools/make-dist

@@ -5,6 +5,9 @@ cd "$(realpath -m "$0"/../..)"
 
 message() { printf "  %-8s %s\n" "$1" "$2" >&2; }
 
+# Set the version number from the state at the time the build was requested
+VERSION="$(git describe --tags --long --dirty | tr '-' '.')"
+
 jumpstart_flags=''
 download_only=''
 while [ $# != 0 ] ; do
@@ -63,5 +66,5 @@ else
 fi
 
 # Do the actual build
-make -s -j"$(nproc)" XZ_OPT='-0' "$@" dist >&2
-make dump-dist
+make -s -j"$(nproc)" XZ_OPT='-0' VERSION="${VERSION}" "$@" dist >&2
+realpath cockpit-${VERSION}.tar.xz  # (only) result to stdout