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Re: Linux Embedded: how to get info from a running service

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On 07/08/2023 23:28, pozz wrote:
> I developed an application (in Python language) that is started by 
> systemd at startup and stay running forever (until the box is rebooted 
> or shutdown).
> 
> The user can get some info of the system by a web application, as a 
> typical router or NAS. The user points his web browser to the local IP 
> address of my Linux box and a graphical interface appears. This web 
> application is written in Python (WSGI) deployed on the box thanks to 
> nginx + gunicorn + Flask.
> 
> Now the question is: how to get infos from a running service such that 
> they can be shown on the web application?
> The infos are specific of my application, they aren't standard. I'm in 
> control of the running service and WSGI application, so I can use 
> whatever solution is better.
> 
> Of course this is a typical IPC scenario: one process is WSGI and the 
> other is the running service.
> I can use shared memory, message queues, named pipes, unix sockets, 
> Internet sockets, D-Bus and many other mechanisms.
> 
> Is there one that is better to use in my case? After some reading, maybe 
> D-Bus can be a good way. I understood systemd already uses D-Bus to 
> exchange infos about its services and units.
> However its implementation is not straightforward as a unix socket with 
> custom messages.
> 
> What do you suggest?
> 
> PS: In the past I read only a few posts regarding Linux development, 
> even if it's for embedded devices. However I don't know how to ask 
> questions related to linux development, I noticed Usenet linux groups 
> are somewhat dead.

I don't know what kind of information you are needing, but an easy 
option might be to have the python service regularly write out a json 
format file with the current status or other information.  The web app 
can have Javascript that regularly reads that file and handles it on the 
user's web browser.  And if you want to go the other way, your Python 
code can use "inotify" waits to see file writes from the web server.

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Linux Embedded: how to get info from a running service pozz <pozzugno@gmail.com> - 2023-08-07 23:28 +0200
  Re: Linux Embedded: how to get info from a running service David Brown <david.brown@hesbynett.no> - 2023-08-08 12:27 +0200
    Re: Linux Embedded: how to get info from a running service pozz <pozzugno@gmail.com> - 2023-08-08 14:59 +0200
      Re: Linux Embedded: how to get info from a running service Grant Edwards <invalid@invalid.invalid> - 2023-08-08 14:31 +0000
      Re: Linux Embedded: how to get info from a running service David Brown <david.brown@hesbynett.no> - 2023-08-08 16:31 +0200
        Re: Linux Embedded: how to get info from a running service pozz <pozzugno@gmail.com> - 2023-08-08 17:14 +0200
          Re: Linux Embedded: how to get info from a running service David Brown <david.brown@hesbynett.no> - 2023-08-08 18:54 +0200
            Re: Linux Embedded: how to get info from a running service pozz <pozzugno@gmail.com> - 2023-08-09 09:27 +0200
              Re: Linux Embedded: how to get info from a running service David Brown <david.brown@hesbynett.no> - 2023-08-09 10:29 +0200
                Re: Linux Embedded: how to get info from a running service Grant Edwards <invalid@invalid.invalid> - 2023-08-09 13:00 +0000

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