systemd support in juju

[Antonio Rosales]

Alexis,
Thanks for sending this out I am also cc'ing juju list as this has an
impact on charm authors.

Charm Authors,
If your charm uses "start", "stop", "restart", "initctl" for service
lifecycle management you'll need to update your charm for Vivid(15.04)
and greater. Recommended charms are only published on the LTS
branches, however if you are targeting 16.04 or wanting to take
advantage of a recent OS for your charm (15.04 and greater), perhaps
arch enablement reasons, you'll need to ensure your charm supports
Systemd.

Note, the below resources and we'll be working on adding some
additional information to jujucharms.com/docs.

-thanks,

On Thu, Mar 12, 2015 at 5:27 PM, Alexis Bruemmer
<alexis.bruemmer at canonical.com> wrote:
> Hi All,
>
> systemd support in juju has been developed and currently is in trunk.  It
> will be available in the 1.23 release scheduled to go beta next week.
> Upstart will continue to be supported as well.  However, versions of juju
> prior to 1.23 will not support systemd.  This means that these versions
> cannot run on the latest vivid images without first switching to upstart.
>
> More information regarding systemd support can be found at:
>
> https://bugs.launchpad.net/juju-core/+bug/1409639
>
> Also below are some notes addressing points several folks have asked about
> over the past month.
>
> The systemd support is new so please do use the 1.23-beta once available
> next week and if you encounter any problems file a bug.  As always juju
> developers are available on #juju-dev or this mailing list if you have
> questions.
>
> Thanks!
> Alexis
>
>  Notes
> ======
>
> Running Older juju on vivid
> ======================
>
> In order to use juju 1.22 and earlier on vivid the host must be
> updated to boot with upstart. This can be done by running "sudo
> apt-get install upstart" followed by "sudo update-grub".  As well, a
> vivid host may be booted with upstart for a single boot.  Upon
> booting, in the grub menu select "Advanced options for Ubuntu" and
> then "Ubuntu, with Linux ... (upstart)".
>
> We are working on updating the dist packages for earlier versions of
> juju to specifically require upstart.
>
> Charms
> =========
>
> Since charms are released on a per-series basis, there is no immediate
> impact from vivid.  The only impact relative to systemd on vivid will
> be to the effort of updating charms for release on vivid.  Most charms
> will be unaffected.  Those that are will be those that currently
> install their own upstart scripts or call upstart-specific commands
> ("start", "stop", "restart", "initctl").  Those that call more generic
> commands like "service" are fine.
>
> Local Provider
> ============
>
> There is a known issue where vivid (systemd) LXC containers on
> non-vivid hosts will not boot.  See
> https://bugs.launchpad.net/ubuntu/+source/lxc/+bug/1347020.  This has
> a direct impact on using local provider on non-vivid hosts under those
> circumstances.  However, everything works fine if local provider is
> run on a vivid host.
>
> There is also an issue with using lxc-create to create vivid
> containers using the ubuntu-cloud template  on a non-vivid host, if
> certain packages have not been updated.  See
> https://bugs.launchpad.net/ubuntu/+source/cloud-utils/+bug/1062671.
> This may impact some users of local provider.
>
> Discovery
> =========
>
> juju decides at run-time on which init system to use.  For local hosts
> this involves inspecting the host and falling back to inferring the
> init system from the juju version information.  For cloud-init the
> init system is deduced strictly from the juju version information
> defined for the to-be-created instance.  Trusty and earlier indicates
> upstart should be used and vivid and later indicates systemd.
> However, there is a feature flag which may be used to force vivid and
> later to use upstart.  Set "JUJU_DEV_FEATURE_FLAGS = legacy-upstart" in your
> shell environment.
>
> Resources
> ==========
> * https://wiki.ubuntu.com/SystemdForUpstartUsers
>
>
>
>
> --
> Alexis Bruemmer
> Juju Core Manager, Canonical Ltd.
> (503) 686-5018
> alexis.bruemmer at canonical.com
>
> --
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>



-- 
Antonio Rosales
Juju Ecosystem
Canonical