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

[Heiko Schocher]

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:

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
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