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From: "Đoàn Trần Công Danh" <congdanhqx@gmail.com>
To: phillip.wood@dunelm.org.uk
Cc: "Eric Sunshine" <sunshine@sunshineco.com>,
	"Lénaïc Huard" <lenaic@lhuard.fr>,
	"Git List" <git@vger.kernel.org>,
	"Junio C Hamano" <gitster@pobox.com>,
	"Derrick Stolee" <dstolee@microsoft.com>,
	"brian m. carlson" <sandals@crustytoothpaste.net>
Subject: Re: [PATCH] maintenance: use systemd timers on Linux
Date: Wed, 5 May 2021 19:19:33 +0700	[thread overview]
Message-ID: <YJKNVX5Nq64wAfvA@danh.dev> (raw)
In-Reply-To: <b1153c47-05cf-877c-587b-8205d8d32816@gmail.com>

On 2021-05-02 15:10:05+0100, Phillip Wood <phillip.wood123@gmail.com> wrote:
> On 02/05/2021 07:45, Eric Sunshine wrote:
> > On Sat, May 1, 2021 at 10:59 AM Lénaïc Huard <lenaic@lhuard.fr> wrote:
> > > The existing mechanism for scheduling background maintenance is done
> > > through cron. On Linux systems managed by systemd, systemd provides an
> > > alternative to schedule recurring tasks: systemd timers.
> > 
> > Thanks for working on this. While `cron` has been the go-to standard
> > for decades, `systemd` is certainly widespread enough that it makes
> > sense to support it, as well.
> 
> Yes, thank you for working on this, it will be very useful to users like me
> who use a linux distribution that does not install a cron daemon by default
> but relies on systemd instead.
> 
> > > The main motivations to implement systemd timers in addition to cron
> > > are:
> > > * cron is optional and Linux systems running systemd might not have it
> > >    installed.
> > > * The execution of `crontab -l` can tell us if cron is installed but not
> > >    if the daemon is actually running.
> 
> Can we use systemctl to see if it is running (and enabled so we know it will
> be restarted after a reboot)?

Not sure if I understand this suggestion.
However, non-systemd systems doesn't have systemctl command to begin
with.

> > > * With systemd, each service is run in its own cgroup and its logs are
> > >    tagged by the service inside journald. With cron, all scheduled tasks
> > >    are running in the cron daemon cgroup and all the logs of the
> > >    user-scheduled tasks are pretended to belong to the system cron
> > >    service.
> > >    Concretely, a user that doesn’t have access to the system logs won’t
> > >    have access to the log of its own tasks scheduled by cron whereas he
> > >    will have access to the log of its own tasks scheduled by systemd
> > >    timer.
> > 
> > The last point is somewhat compelling. A potential counterargument is
> > that `cron` does send email to the user by default if any output is
> > generated by the cron job. However, it seems quite likely these days
> > that many systems either won't have local mail service enabled or the
> > user won't bother checking the local mailbox. It's a minor point, but
> > if you re-roll it might make sense for the commit message to expand
> > the last point by saying that although `cron` attempts to send email,
> > that email may go unseen by the user.
> > 
> > > In order to schedule git maintenance, we need two unit template files:
> > > * ~/.config/systemd/user/git-maintenance@.service
> > >    to define the command to be started by systemd and
> > > * ~/.config/systemd/user/git-maintenance@.timer
> > >    to define the schedule at which the command should be run.

I think it would be better to change ~/.config here to
$XDG_CONFIG_HOME, as others also points out in another comments.

[..snip..]

> > > +`git maintenance start` will overwrite these files and start the timer
> > > +again with `systemctl --user`, so any customization should be done by
> > > +creating a drop-in file
> > > +`~/.config/systemd/user/git-maintenance@.service.d/*.conf`.

Ditto.

> > Will `systemd` users generally understand what filename to create in
> > the "...@.service.d/" directory, and will they know what to populate
> > the file with? (Genuine question; I've never dealt with that.)
> 
> I think it would be helpful to explicitly mention the file names (I don't
> think I could tell you what they are without reading the relevant systemd
> man page)

[..snip..]

> > > +static char *systemd_timer_timer_filename()
> > > +{
> > > +       const char *filename = "~/.config/systemd/user/git-maintenance@.timer";
> > > +       char *expanded = expand_user_path(filename, 0);
> > > +       if (!expanded)
> > > +               die(_("failed to expand path '%s'"), filename);
> > > +
> > > +       return expanded;
> > > +}
> > 
> > I was curious whether this would fail if `.config/systemd/user/`
> > didn't already exist, but looking at the implementation of
> > expand_user_path() , I see that it doesn't require the path to already
> > exist if you pass 0 for the second argument as you do here. Okay.
> 
> Do we need to worry about $XDG_CONFIG_HOME rather than hard coding
> "~/.config/". There is a function xdg_config_home() that takes care of this.

-- 
Danh

  reply	other threads:[~2021-05-05 12:19 UTC|newest]

Thread overview: 138+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-05-01 14:52 [PATCH] maintenance: use systemd timers on Linux Lénaïc Huard
2021-05-01 20:02 ` brian m. carlson
2021-05-02  5:28 ` Bagas Sanjaya
2021-05-02  6:49   ` Eric Sunshine
2021-05-02  6:45 ` Eric Sunshine
2021-05-02 14:10   ` Phillip Wood
2021-05-05 12:19     ` Đoàn Trần Công Danh [this message]
2021-05-05 14:57       ` Phillip Wood
2021-05-05 12:01   ` Ævar Arnfjörð Bjarmason
2021-05-09 22:34     ` Lénaïc Huard
2021-05-10 13:03       ` Ævar Arnfjörð Bjarmason
2021-05-02 11:12 ` Bagas Sanjaya
2021-05-03 12:04 ` Derrick Stolee
2021-05-09 21:32 ` [PATCH v2 0/1] " Lénaïc Huard
2021-05-09 21:32   ` [PATCH v2 1/1] " Lénaïc Huard
2021-05-10  1:20     ` Đoàn Trần Công Danh
2021-05-10  2:48       ` Eric Sunshine
2021-05-10  6:25         ` Junio C Hamano
2021-05-12  0:29           ` Đoàn Trần Công Danh
2021-05-12  6:59             ` Felipe Contreras
2021-05-12 13:26               ` Phillip Wood
2021-05-12 13:38             ` Phillip Wood
2021-05-12 15:41               ` Đoàn Trần Công Danh
2021-05-10 18:03     ` Phillip Wood
2021-05-10 18:25       ` Eric Sunshine
2021-05-10 20:09         ` Phillip Wood
2021-05-10 20:52           ` Eric Sunshine
2021-06-08 14:55       ` Lénaïc Huard
2021-05-10 19:15     ` Martin Ågren
2021-05-11 14:50     ` Phillip Wood
2021-05-11 17:31     ` Derrick Stolee
2021-05-20 22:13   ` [PATCH v3 0/4] " Lénaïc Huard
2021-05-20 22:13     ` [PATCH v3 1/4] cache.h: rename "xdg_config_home" to "xdg_config_home_git" Lénaïc Huard
2021-05-20 23:44       ` Đoàn Trần Công Danh
2021-05-20 22:13     ` [PATCH v3 2/4] maintenance: introduce ENABLE/DISABLE for code clarity Lénaïc Huard
2021-05-20 22:13     ` [PATCH v3 3/4] maintenance: `git maintenance run` learned `--scheduler=<scheduler>` Lénaïc Huard
2021-05-21  9:52       ` Bagas Sanjaya
2021-05-20 22:13     ` [PATCH v3 4/4] maintenance: optionally use systemd timers on Linux Lénaïc Huard
2021-05-21  9:59       ` Bagas Sanjaya
2021-05-21 16:59         ` Derrick Stolee
2021-05-22  6:57           ` Johannes Schindelin
2021-05-23 18:36             ` Felipe Contreras
2021-05-23 23:27               ` brian m. carlson
2021-05-24  1:18                 ` Felipe Contreras
2021-05-24  7:03                 ` Ævar Arnfjörð Bjarmason
2021-05-24 15:51                   ` Junio C Hamano
2021-05-25  1:50                     ` Johannes Schindelin
2021-05-25 11:13                       ` Felipe Contreras
2021-05-26 10:29                       ` CoC, inclusivity etc. (was "Re: [...] systemd timers on Linux") Ævar Arnfjörð Bjarmason
2021-05-26 16:05                         ` Felipe Contreras
2021-05-27 14:24                         ` Jeff King
2021-05-27 17:30                           ` Felipe Contreras
2021-05-27 23:58                           ` Junio C Hamano
2021-05-28 14:44                           ` Phillip Susi
2021-05-30 21:58                             ` Jeff King
2021-05-24 17:52                   ` [PATCH v3 4/4] maintenance: optionally use systemd timers on Linux Felipe Contreras
2021-05-24  7:15     ` [PATCH v4 0/4] add support for " Lénaïc Huard
2021-05-24  7:15       ` [PATCH v4 1/4] cache.h: Introduce a generic "xdg_config_home_for(…)" function Lénaïc Huard
2021-05-24  9:33         ` Phillip Wood
2021-05-24 12:23           ` Đoàn Trần Công Danh
2021-05-24  7:15       ` [PATCH v4 2/4] maintenance: introduce ENABLE/DISABLE for code clarity Lénaïc Huard
2021-05-24  9:41         ` Phillip Wood
2021-05-24 12:36           ` Đoàn Trần Công Danh
2021-05-25  7:18             ` Lénaïc Huard
2021-05-25  8:02               ` Junio C Hamano
2021-05-24  9:47         ` Ævar Arnfjörð Bjarmason
2021-05-24  7:15       ` [PATCH v4 3/4] maintenance: `git maintenance run` learned `--scheduler=<scheduler>` Lénaïc Huard
2021-05-24 10:12         ` Phillip Wood
2021-05-30  6:39           ` Lénaïc Huard
2021-05-30 10:16             ` Phillip Wood
2021-05-24  7:15       ` [PATCH v4 4/4] maintenance: add support for systemd timers on Linux Lénaïc Huard
2021-05-24  9:55         ` Ævar Arnfjörð Bjarmason
2021-05-24 16:39           ` Eric Sunshine
2021-05-24 18:08         ` Felipe Contreras
2021-05-26 10:26         ` Phillip Wood
2021-05-24  9:04       ` [PATCH v4 0/4] " Junio C Hamano
2021-06-08 13:39       ` [PATCH v5 0/3] " Lénaïc Huard
2021-06-08 13:39         ` [PATCH v5 1/3] cache.h: Introduce a generic "xdg_config_home_for(…)" function Lénaïc Huard
2021-06-08 13:39         ` [PATCH v5 2/3] maintenance: `git maintenance run` learned `--scheduler=<scheduler>` Lénaïc Huard
2021-06-08 13:40         ` [PATCH v5 3/3] maintenance: add support for systemd timers on Linux Lénaïc Huard
2021-06-09  9:34           ` Jeff King
2021-06-09 15:01           ` Phillip Wood
2021-06-09  0:21         ` [PATCH v5 0/3] " Junio C Hamano
2021-06-09 14:54         ` Phillip Wood
2021-06-12 16:50         ` [PATCH v6 0/3] maintenance: " Lénaïc Huard
2021-06-12 16:50           ` [PATCH v6 1/3] cache.h: Introduce a generic "xdg_config_home_for(…)" function Lénaïc Huard
2021-06-12 16:50           ` [PATCH v6 2/3] maintenance: `git maintenance run` learned `--scheduler=<scheduler>` Lénaïc Huard
2021-06-14  4:36             ` Eric Sunshine
2021-06-16 18:12               ` Derrick Stolee
2021-06-17  4:11                 ` Eric Sunshine
2021-06-17 14:26               ` Phillip Wood
2021-07-02 15:04               ` Lénaïc Huard
2021-06-12 16:50           ` [PATCH v6 3/3] maintenance: add support for systemd timers on Linux Lénaïc Huard
2021-07-02 14:25           ` [PATCH v7 0/3] " Lénaïc Huard
2021-07-02 14:25             ` [PATCH v7 1/3] cache.h: Introduce a generic "xdg_config_home_for(…)" function Lénaïc Huard
2021-07-02 14:25             ` [PATCH v7 2/3] maintenance: `git maintenance run` learned `--scheduler=<scheduler>` Lénaïc Huard
2021-07-06 19:56               ` Ævar Arnfjörð Bjarmason
2021-07-06 20:52                 ` Junio C Hamano
2021-07-13  0:15                   ` Jeff King
2021-07-13  2:22                     ` Eric Sunshine
2021-07-13  3:56                       ` Jeff King
2021-07-13  5:17                         ` Eric Sunshine
2021-07-13  7:04                       ` Bagas Sanjaya
2021-07-06 21:18                 ` Felipe Contreras
2021-08-23 20:06                 ` Lénaïc Huard
2021-08-23 22:30                   ` Junio C Hamano
2021-07-02 14:25             ` [PATCH v7 3/3] maintenance: add support for systemd timers on Linux Lénaïc Huard
2021-07-06 20:03               ` Ævar Arnfjörð Bjarmason
2021-07-02 18:18             ` [PATCH v7 0/3] " Junio C Hamano
2021-07-06 13:18             ` Phillip Wood
2021-08-23 20:40             ` [PATCH v8 " Lénaïc Huard
2021-08-23 20:40               ` [PATCH v8 1/3] cache.h: Introduce a generic "xdg_config_home_for(…)" function Lénaïc Huard
2021-08-23 20:40               ` [PATCH v8 2/3] maintenance: `git maintenance run` learned `--scheduler=<scheduler>` Lénaïc Huard
2021-08-24 17:45                 ` Derrick Stolee
2021-08-23 20:40               ` [PATCH v8 3/3] maintenance: add support for systemd timers on Linux Lénaïc Huard
2021-08-24 17:45                 ` Derrick Stolee
2021-08-24 17:47               ` [PATCH v8 0/3] " Derrick Stolee
2021-08-27 21:02               ` [PATCH v9 " Lénaïc Huard
2021-08-27 21:02                 ` [PATCH v9 1/3] cache.h: Introduce a generic "xdg_config_home_for(…)" function Lénaïc Huard
2021-08-27 21:02                 ` [PATCH v9 2/3] maintenance: `git maintenance run` learned `--scheduler=<scheduler>` Lénaïc Huard
2021-08-27 23:54                   ` Ramsay Jones
2021-08-27 21:02                 ` [PATCH v9 3/3] maintenance: add support for systemd timers on Linux Lénaïc Huard
2021-09-04 20:54                 ` [PATCH v10 0/3] " Lénaïc Huard
2021-09-04 20:54                   ` [PATCH v10 1/3] cache.h: Introduce a generic "xdg_config_home_for(…)" function Lénaïc Huard
2021-09-04 20:54                   ` [PATCH v10 2/3] maintenance: `git maintenance run` learned `--scheduler=<scheduler>` Lénaïc Huard
2021-09-04 20:55                   ` [PATCH v10 3/3] maintenance: add support for systemd timers on Linux Lénaïc Huard
2021-09-07 16:48                   ` [PATCH v10 0/3] " Derrick Stolee
2021-09-08 11:44                     ` Derrick Stolee
2021-09-09  5:52                       ` Lénaïc Huard
2021-09-09 19:55                         ` Derrick Stolee
2021-09-27 12:50                           ` Ævar Arnfjörð Bjarmason
2021-09-27 21:44                             ` Lénaïc Huard
2021-08-17 17:22         ` [PATCH v5 0/3] " Derrick Stolee
2021-08-17 19:43           ` Phillip Wood
2021-08-17 20:29             ` Derrick Stolee
2021-08-18  5:56           ` Lénaïc Huard
2021-08-18 13:28             ` Derrick Stolee
2021-08-18 18:23               ` Junio C Hamano

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