[winswitch] Can't start xpra session

[Antoine Martin]

On 30/08/18 23:41, Anthony Stone wrote:
> Antoine,
> 
> Thanks for the suggestions. This is what happens:
Please always keep the list CCed.

> On 30/08/18 04:22, Antoine Martin via shifter-users wrote:
>> Directly on the server (ie: via ssh), try to start the session locally:
>> xpra start :100 --start="gnome-terminal --window-with-profile=Blue"
> 
> 17:22:05 $ xpra start :100 --start="gnome-terminal
> --window-with-profile=Blue"
> 2018-08-30 17:22:46,020 server failure: disconnected before the session
> could be established
> 2018-08-30 17:22:46,020 server requested disconnect: server error
> (failed to start a new session)
> Warning: cannot use the system proxy for 'start' subcommand,
>  unknown general failure
>  more information may be available in your system log
> 
> The system log contains the following. This seems to be an
> authentication failure, but I don't know how to fix it.
> 
> Aug 30 17:22:32 whirligig systemd[1]: Started Session 2509 of user ajs1.
> Aug 30 17:22:32 whirligig xpra[1192]: reenter password for
> pam_mount:(pam_mount.c:477): warning: could not obtain password
> interactively either
> Aug 30 17:22:32 whirligig xpra[1192]: reenter password for
> pam_mount:(pam_mount.c:477): warning: could not obtain password
> interactively either
Here is what I think is happening: when we start a proper pam session
via root (this is what the "starting via proxy" does), we go through the
pam session configuration.
Your OS seems to include "pam_mount" in there, and that seems to want to
ask for a password to do its job.
I have no idea why that is, or why it isn't failing more gracefully.

> Aug 30 17:22:32 whirligig xpra[1192]: 2018-08-30 17:22:32,475 Error:
> pam_open_session failed: 6
> Aug 30 17:22:32 whirligig xpra[1192]: 2018-08-30 17:22:32,476
> Permission denied
> Aug 30 17:22:32 whirligig xpra[1192]: Entering daemon mode; any further
> errors will be reported to:
> Aug 30 17:22:32 whirligig xpra[1192]:   /run/user/1013/xpra/:100.log
> Aug 30 17:22:46 whirligig xpra[1192]: Error: failed to start server
> subprocess:
> Aug 30 17:22:46 whirligig xpra[1192]:  failed to identify the new server
> display!
The easiest solution to this problem is to not use the proxy, set:
start-via-proxy=no
in your /etc/xpra/conf.d/60_server.conf

On this subject, there seems to be so many ways that distributions
manage to configure (break) pam sessions, and logind's KillUserProcesses
still defaults to "no" after all these years, so future versions will
revert to not using the system wide proxy by default.
Those who want the features that require it will have to re-enable it.

Cheers,
Antoine