[winswitch] Can't start xpra session

Post by Anthony Stone via shifter-users
Antoine,
I am puzzled by the following. I tried to start an xpra session on my

(..)

Post by Anthony Stone via shifter-users
Am I doing something daft, or is there a bug? The xpra start command has
worked many times before -- I usually use ctrl-R to retrieve the
previous start command each time, rather than retyping it.

Directly on the server (ie: via ssh), try to start the session locally:
xpra start :100 --start="gnome-terminal --window-with-profile=Blue"

Then check it has started:
xpra list

And if not, have a look at the server log file and send it here if you
can't make sense of it.

At this point, you should be able to connect (use "attach" instead of
"start" and with the display number specified above with start):
xpra attach ssh://yourhost/100

If things still fail, please provide the full details (full os version
at both ends, etc).
Just be aware of the recent incompatibility with non-bash login shells.
(this should be fixed in the next stable update)

Cheers,
Antoine

Post by Anthony Stone via shifter-users
$ xpra --version
xpra v2.3.3-r20112
Anthony Stone

Antoine Martin via shifter-users

2018-08-30 17:13:29 UTC

Please always keep the list CCed.

Post by Antoine Martin via shifter-users
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.

Post by Anthony Stone via shifter-users
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
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
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

Anthony Stone via shifter-users

2018-08-31 09:10:31 UTC

Post by Antoine Martin via shifter-users

Antoine,

As recommended, I have set
start-via-proxy=no
in /etc/xpra/conf.d/60_server.conf
(and restarted the server)
and xpra now starts normally.

Many thanks for the prompt and helpful advice.

Anthony

Please always keep the list CCed.

Post by Antoine Martin via shifter-users
xpra start :100 --start="gnome-terminal --window-with-profile=Blue"

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

Anthony Stone via shifter-users

2018-09-02 09:51:27 UTC

Post by Antoine Martin via shifter-users

Antoine,

For the record: I find that after I stop an xpra session, I can't start
a new session on the same display with the same command that I have
always used previously, i.e.
xpra start ssh/whirligig/100 --start="gnome-terminal ..."
The log tells me that the lock file for the previous session needs to be
deleted, or that there is already an X session with that name, even if I
have exited from the terminal shell.

However I can start a session with the same display using
xpra start ssh/whirligig/100 --use-display=yes --start="gnome-terminal ..."
In this case any terminal windows from the previous session that I
haven't closed explicitly reappear along with the new one. Previously
they were closed automatically when I invoked "xpra stop", which is what
I would prefer to happen.

Anthony

Post by Anthony Stone via shifter-users
Antoine,
As recommended, I have set
start-via-proxy=no
in /etc/xpra/conf.d/60_server.conf
(and restarted the server)
and xpra now starts normally.
Many thanks for the prompt and helpful advice.
Anthony

Please always keep the list CCed.

Post by Antoine Martin via shifter-users
xpra start :100 --start="gnome-terminal --window-with-profile=Blue"

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Antoine Martin via shifter-users

2018-09-02 10:18:19 UTC

Post by Antoine Martin via shifter-users

Post by Anthony Stone via shifter-users
Antoine,
For the record: I find that after I stop an xpra session, I can't start
a new session on the same display with the same command that I have
always used previously, i.e.
xpra start ssh/whirligig/100 --start="gnome-terminal ..."
The log tells me that the lock file for the previous session needs to be
deleted, or that there is already an X session with that name, even if I
have exited from the terminal shell.
However I can start a session with the same display using
xpra start ssh/whirligig/100 --use-display=yes --start="gnome-terminal ..."
In this case any terminal windows from the previous session that I
haven't closed explicitly reappear along with the new one. Previously
they were closed automatically when I invoked "xpra stop", which is what
I would prefer to happen.

Which version are you running?

I believe you are hitting this bug:
http://xpra.org/trac/ticket/1943

The workaround will be included in the next stable update.
In the meantime, since the fix is a trivial one-liner, you could apply
it by hand to your existing installation.

Cheers,
Antoine

Post by Anthony Stone via shifter-users
Anthony

Please always keep the list CCed.