[PATCH v3] tbot_contrib/utils.py: collect some usefull linux utils

[Harald Seiler]

Hello Heiko,

On Wed, 2020-04-22 at 10:01 +0200, Heiko Schocher wrote:
> Hello Harald,
> 
> Am 22.04.2020 um 09:07 schrieb Harald Seiler:
> > Hello Heiko,
> > 
> > On Wed, 2020-04-22 at 07:01 +0200, Heiko Schocher wrote:
> > > collect usefull linux utils functions. Start with
> > > 
> > > ensure_sd_unit(lnx: linux.LinuxShell, services: typing.List[str])
> > > 
> > > check if all systemd services in list services run on linux
> > > machine lnx. If not, try to start them.
> > > 
> > > Signed-off-by: Heiko Schocher <hs at denx.de>
> > > ---
> > > 
> > > Changes in v3:
> > > - fix commit message
> > >    rename check_systemd_services_running() to ensure_sd_unit()
> > > 
> > > Changes in v2:
> > > - added comments from Harald
> > >    - rename check_systemd_services_running() to ensure_sd_unit()
> > >    - fix Copyright
> > >    - correct type-annotation for services
> > >    - use lnx.test()
> > >    - use "is-active" instead "status" for getting state of service
> > > - added a services cache, so we only check once per linux
> > >    machine, if systemd services run.
> > 
> > The cache is a great idea, thanks for adding that!  On that note, I've
> > been playing with the idea of adding a new decorator for this kind of
> > purpose.  It seems to happen quite often that some action needs to happen
> > once for each machine it is called on.
> 
> May a good idea, yes!
> 
> > >   tbot_contrib/utils.py | 42 ++++++++++++++++++++++++++++++++++++++++++
> > >   1 file changed, 42 insertions(+)
> > >   create mode 100644 tbot_contrib/utils.py
> > > 
> > > diff --git a/tbot_contrib/utils.py b/tbot_contrib/utils.py
> > > new file mode 100644
> > > index 0000000..ee91d00
> > > --- /dev/null
> > > +++ b/tbot_contrib/utils.py
> > > @@ -0,0 +1,42 @@
> > > +# tbot, Embedded Automation Tool
> > > +# Copyright (C) 2020  Heiko Schocher
> > > +#
> > > +# This program is free software: you can redistribute it and/or modify
> > > +# it under the terms of the GNU General Public License as published by
> > > +# the Free Software Foundation, either version 3 of the License, or
> > > +# (at your option) any later version.
> > > +#
> > > +# This program is distributed in the hope that it will be useful,
> > > +# but WITHOUT ANY WARRANTY; without even the implied warranty of
> > > +# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
> > > +# GNU General Public License for more details.
> > > +#
> > > +# You should have received a copy of the GNU General Public License
> > > +# along with this program.  If not, see <https://www.gnu.org/licenses/>;;;;.
> > > +
> > > +from tbot.machine import linux
> > > +import typing
> > > +
> > > +
> > > +_SERVICES_CACHE: typing.Dict[str, typing.Dict[str, bool]] = {}
> > > +
> > > +
> > > +def ensure_sd_unit(lnx: linux.LinuxShell, services: typing.List[str]) -> None:
> > > +    """
> > > +    check if all systemd services in list services run on linux machine lnx.
> > > +    If not, try to start them.
> > > +
> > > +    :param lnx: linux shell
> > > +    :param services: list of systemd services
> > > +    """
> > > +    if lnx.name not in _SERVICES_CACHE:
> > > +        _SERVICES_CACHE[lnx.name] = {}
> > 
> > Small nitpick:  Using the name as the key for your cache is not ideal
> > because there is no guarantee that we won't see multiple machines with the
> > same name.  Instead, you can use the machine itself as the key like I have
> > done in check_for_tool [1].  This is possible because machines implement
> > the hash() protocol (and cloned machines all yield the same hash).
> 
> Hmm... I must try it, but I think, I did first:
> 
> _SERVICES_CACHE[lnx] = {}
> 
> and it did not worked ... Yes, just tried again:

Huh, this means the two machines which are created here are not proper
clones of each other ... I'll have to take a closer look.  I guess this is
an SSHConnector under the hood?

For now, I'd be fine with your version as is; this is not a big issue.
I can adjust it later, once the other problem is fixed.

> hs at lab-1:tbot-tbot2go  [wandboard-devel-messe] $ tbot @argswandboardlab1 interactive_uboot
> tbot starting ...
> ├─Flags:
> │ 'lab-1-build'
> ├─Calling interactive_uboot ...
> │   ├─[local] ssh -o BatchMode=yes -i /home/hs/.ssh/id_rsa -p 22 hs at 192.168.1.109
> │   ├─[lab1] systemctl is-active nfs-server.service --no-pager
> │   │    ## active
> │   ├─[lab1] systemctl is-active tftp.socket --no-pager
> │   │    ## active
> │   ├─[local] ssh -o BatchMode=yes -i /home/hs/.ssh/id_rsa -p 22 hs at 192.168.1.109
> │   ├─[lab1] systemctl is-active nfs-server.service --no-pager
> │   │    ## active
> │   ├─[lab1] systemctl is-active tftp.socket --no-pager
> │   │    ## active
> │   ├─[lab1] kermit /home/hs/kermrc_wandboard
> 
> > > +    for s in services:
> > > +        if s in _SERVICES_CACHE[lnx.name]:
> > > +            continue
> > > +
> > > +        if not lnx.test("systemctl", "is-active", s, "--no-pager"):
> > 
> > You don't need `--no-pager` for is-active.
> 
> Indeed.
> 
> > > +            lnx.exec0("sudo", "systemctl", "start", s)
> > > +
> > > +        _SERVICES_CACHE[lnx.name][s] = True
> > 
> > [1]: https://github.com/Rahix/tbot/blob/master/tbot/tc/shell.py#L173
> > 
> 
> bye,
> Heiko

Regards,
-- 
Harald