lightdm-service-type is almost unusable

Hi Guix,

This is to report some of the issues and workarounds when trying to

setup lightdm-service-type.

1. Unable to choose a session (https://issues.guix.gnu.org/68055)

This appearently never worked: https://issues.guix.gnu.org/57168#0

This means one currently has to specify the default session with

something like

(service lightdm-service-type

(lightdm-configuration

(seats

(list

(lightdm-seat-configuration

(name "*")

(user-session "xfce"))))))

2. gtkgreeter chooses the wrong default session

This is related to 1. If one already had set the default user session

(i.e. from using default configuration => default.xsession) or one wants

to use a different session, lightdm gtkgreeter still requests the old one.

After a lot of searching I found this

https://github.com/Xubuntu/lightdm-gtk-greeter/issues/163.

I.e. lightdm asks the accountsservice for the default-session rather

than lightm which still has cashed the old/wrong one. Thus with no

option to select a different session one is unable to login.

The workaorund here is to delete/modify /var/lib/AccountService/users to

make sure accountsservice recreates/updates the configurration.

3. After the lightdms users .Xauthority file is created it has wrong

permissions on subsequent boots.

this can be "fixed" by manually setting less restrictive permissions on

/var/lib/lightdm/.Xauthority

This might be fixed by making the lightdm-activiation snippet actually

useful: It currently searches for a file named "directory" to fix

permissions rather than the content of the variable 'directory'.

(find-files "directory" #:directories? #t) vs

(find-files directory #:directories? #t)

here

4. tigervnnc

default tigervnc is (file-append tigervnc-server "bin/Xvnc") rather than

(file-append tigervnc-server "/bin/Xvnc")

Hi Dariqq,

Dariqq <dariqq@posteo.net> writes:

Thank you for taking the time to report these detailed findings!

Indeed. This definitely makes the session manager much less useful.

I'd really like to find a solution to that; I think the issue is

reported upstream here:

Just a hunch: perhaps something in the environment the greeter

runs is missing to have d-bus communication properly working?

[...]

Fixed.

Also fixed (see commit e4e1e16bc1).

--

Thanks,

Maxim

Hi Maxim

On 23.10.24 16:48, Maxim Cournoyer wrote:

Found all these while trying to switch from xfce to mate on a 32 bit

machine (plus skipping some tests in mates dependency tree to get it to

build) and spent way to much time trying to understand how to change the

default session.

Remotivated by your response I looked into how the greeter actually

finds the session:

1. The menu just calls out to lightdm_get_sessions

2. This eventually reaches update_sessions

Could it just be that it is using the "wrong" values for the session dir

and not the ones we specified in the lightdm config?

From what config files (if any) are we reading here?

If this is indeed the issue can we set sysconfdir to /etc and let it

read the lightdm config file from /etc/lightdm/lightdm.conf (via

config_load_from_standard_locations)?

I tried something like this (diff attached) and seems to work. I was

able to choose between xfce and mate and log into either of them.

(only slightly awkward thing is that wed need to overwrite sysconfdir

for 'make install' and should probably rename the

lightdm-configuration->greeters-config-dir function).

Thanks :)

Wow, good news.

Some month ago, I have spend many times to find why session can not be

found, but not success

--

I have tested and found that:

In lightdm-gtk-greeter, the following line run success and return no session.

items = lightdm_get_sessions ();

But, in lightdm, the following function in liblightdm-gobject/session.c is not called:

/**

*

*

**/

GList *

lightdm_get_sessions (void)

{

g_debug ("Run lightdm_get_sessions");

update_sessions ();

return local_sessions;

}

I do not know why, seem to very confuse.

--

[#:configure-flags]: Set sysconfdir to /etc.

[#:phases]: Overwrite sysconfdir in 'installE. for installing sample config files

Change-Id: If9c6ce810c726551bd3bf568d50cad8680829262

---

gnu/packages/display-managers.scm | 7 ++++++-

1 file changed, 6 insertions(+), 1 deletion(-)

This changes lightdm and the service to use the config file from a well-known location in /etc/lightdm/lightdm.conf s.t. the gtk-greeter knows about our custom "sessions-directory".

I then removed the custom config file from the lightdm servcice and removed passing XDG_CONFIG_DIRS which are no longer neccesary.

Renamed lightdm-configuration->greeters-config-dir to just lightdm-configuration-directory (inspired by how the dbus-service names its directory) and also moved the etc-extension into a seperate procedure for consistency with other services.

I tested this on my i686 pc and ran 'make check-system TESTS=lightdm' successfully

This is also the approach done on NixOS, see

* https://github.com/NixOS/nixpkgs/blob/nixos-unstable/pkgs/applications/display-managers/lightdm/default.nix#L93

*https://github.com/NixOS/nixpkgs/blob/nixos-unstable/nixos/modules/services/x11/display-managers/lightdm.nix#L259

Fixes https://issues.guix.gnu.org/68055

Dariqq (2):

gnu: lightdm: Use global sysconfdir.

gnu: lightdm-service-type: Add lightdm.conf to /etc/lightdm.

gnu/packages/display-managers.scm | 7 ++++-

gnu/services/lightdm.scm | 48 ++++++++++++++-----------------

2 files changed, 27 insertions(+), 28 deletions(-)

base-commit: ea11d3608566174c4bae70faa4f9d0c67748d2db

--

2.46.0

(lightdm-configuration->greeters-config-dir): Rename to

lightdm-configuration-directory and add the lightdm-configuration-file.

(lightdm-shepherd-service): Don't pass the configuration file, don't set

XDG_CONFIG_DIRS

(lightdm-etc-service): New procedure.

(lightdm-service-type): Use lightdm-etc-service as the etc-extension.

Change-Id: I982ec1f7bdfd085621f45a8a1e4b175ab481202f

---

gnu/services/lightdm.scm | 48 ++++++++++++++++++----------------------

1 file changed, 21 insertions(+), 27 deletions(-)

tags 73859 + patch

quit