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

[Harald Seiler]

Hello Heiko,

thanks for the patch, this is quite useful!

On Mon, 2020-04-20 at 15:03 +0200, Heiko Schocher wrote:
> collect usefull linux utils functions. Start with
> 
> check_systemd_services_running(lnx: linux.LinuxShell, services: list)

Can we shorten the name a bit?  I'd suggest something like
`ensure_running` although feel free to use something else if you have
a better idea ...

> 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>
> ---
> 
>  tbot_contrib/utils.py | 31 +++++++++++++++++++++++++++++++
>  1 file changed, 31 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..8073f89
> --- /dev/null
> +++ b/tbot_contrib/utils.py
> @@ -0,0 +1,31 @@
> +# tbot, Embedded Automation Tool
> +# Copyright (C) 2020  Harald Seiler

I guess this shouldn't be me ;)

> +#
> +# 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
> +
> +
> +def check_systemd_services_running(lnx: linux.LinuxShell, services: list) -> None:

The correct type-annotation for services would be `typing.List[str]`.
You'll also need to import the typing module for that.

> +    """
> +    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
> +    """
> +    for s in services:
> +        ret = lnx.exec("systemctl", "status", s, "--no-pager")
> +        if ret[0] != 0:

I think it is more robust to use `systemctl is-active` for this check.
Also, you can use `lnx.test()` which makes this a bit more concise:

    if lnx.test("systemctl", "is-active", s):

> +            lnx.test("sudo", "systemctl", "start", s)

This one should be lnx.exec0().  test() will not raise an excepion in case
of an error so failure to start the unit would not be noticed.

Cheers,
-- 
Harald