Re: [RFC PATCH 1/5] maintenance: package systemd units

> On Thu, Mar 21, 2024 at 02:38:36PM +0100, Max Gautier wrote:
> > On Thu, Mar 21, 2024 at 01:37:30PM +0100, Patrick Steinhardt wrote:
> > > On Mon, Mar 18, 2024 at 04:31:15PM +0100, Max Gautier wrote:
> > > 
> > > It would be great to document _why_ we want to package the systemd units
> > > alongside with Git.
> > > 
> > > > Signed-off-by: Max Gautier <mg@max.gautier.name>
> > > > ---
> > > >  Makefile                              |  4 ++++
> > > >  systemd/user/git-maintenance@.service | 16 ++++++++++++++++
> > > >  systemd/user/git-maintenance@.timer   |  9 +++++++++
> > > >  3 files changed, 29 insertions(+)
> > > >  create mode 100644 systemd/user/git-maintenance@.service
> > > >  create mode 100644 systemd/user/git-maintenance@.timer
> > > > 
> > > > diff --git a/Makefile b/Makefile
> > > > index 4e255c81f2..276b4373c6 100644
> > > > --- a/Makefile
> > > > +++ b/Makefile
> > > > @@ -619,6 +619,7 @@ htmldir = $(prefix)/share/doc/git-doc
> > > >  ETC_GITCONFIG = $(sysconfdir)/gitconfig
> > > >  ETC_GITATTRIBUTES = $(sysconfdir)/gitattributes
> > > >  lib = lib
> > > > +libdir = $(prefix)/lib
> > > >  # DESTDIR =
> > > >  pathsep = :
> > > >  
> > > > @@ -1328,6 +1329,8 @@ BUILTIN_OBJS += builtin/verify-tag.o
> > > >  BUILTIN_OBJS += builtin/worktree.o
> > > >  BUILTIN_OBJS += builtin/write-tree.o
> > > >  
> > > > +SYSTEMD_USER_UNITS := $(wildcard systemd/user/*)
> > > > +
> > > >  # THIRD_PARTY_SOURCES is a list of patterns compatible with the
> > > >  # $(filter) and $(filter-out) family of functions. They specify source
> > > >  # files which are taken from some third-party source where we want to be
> > > > @@ -3469,6 +3472,7 @@ install: all
> > > >  	$(INSTALL) -m 644 $(SCRIPT_LIB) '$(DESTDIR_SQ)$(gitexec_instdir_SQ)'
> > > >  	$(INSTALL) $(INSTALL_STRIP) $(install_bindir_xprograms) '$(DESTDIR_SQ)$(bindir_SQ)'
> > > >  	$(INSTALL) $(BINDIR_PROGRAMS_NO_X) '$(DESTDIR_SQ)$(bindir_SQ)'
> > > > +	$(INSTALL) -Dm 644 -t '$(DESTDIR_SQ)$(libdir)/systemd/user' $(SYSTEMD_USER_UNITS)
> > > 
> > > I wonder whether we want to unconditionally install those units. Many of
> > > the platforms that we support don't even have systemd available, so
> > > certainly it wouldn't make any sense to install it on those platforms.
> > > 
> > > Assuming that this is something we want in the first place I thus think
> > > that we should at least make this conditional and add some platform
> > > specific quirk to "config.mak.uname".
> > > 
> > 
> > We probably want that (conditional install) but I'm not sure where that
> > should go ; I'm not super familiar with autoconf. 
> > 
> > I just noticed than man 7 daemon (shipped by systemd) propose the
> > following snippet for installing systemd system services (should be easy
> > enough to adapt for user ervices, I think):
> > 
> > PKG_PROG_PKG_CONFIG()
> > AC_ARG_WITH([systemdsystemunitdir],
> >     [AS_HELP_STRING([--with-systemdsystemunitdir=DIR], [Directory for systemd service files])],,
> >     [with_systemdsystemunitdir=auto])
> > AS_IF([test "x$with_systemdsystemunitdir" = "xyes" -o "x$with_systemdsystemunitdir" = "xauto"], [
> >     def_systemdsystemunitdir=$($PKG_CONFIG --variable=systemdsystemunitdir systemd)
> > 
> >     AS_IF([test "x$def_systemdsystemunitdir" = "x"],
> >   [AS_IF([test "x$with_systemdsystemunitdir" = "xyes"],
> >    [AC_MSG_ERROR([systemd support requested but pkg-config unable to query systemd package])])
> >    with_systemdsystemunitdir=no],
> >   [with_systemdsystemunitdir="$def_systemdsystemunitdir"])])
> > AS_IF([test "x$with_systemdsystemunitdir" != "xno"],
> >      [AC_SUBST([systemdsystemunitdir], [$with_systemdsystemunitdir])])
> > AM_CONDITIONAL([HAVE_SYSTEMD], [test "x$with_systemdsystemunitdir" != "xno"])
> > 
> > Would something like that work ?
> 
> Probably. But while we do have autoconf wired up, the primary way of
> building Git does not use it, but rather uses `config.mak.uname`. I'd
> recommend to have a look at it to figure out how we handle other
> build-time options there.
> 
> Patrick