DICE / Ubuntu (20.04) Draft Release Notes for Staff

→ Please see user-facing DICE Ubuntu release notes. These include more guidance and confirmed issues only.

→ This document will also feed the DICE Ubuntu follow-on project.

If you're interested in the work in progress, read on.

DICE / Ubuntu (20.04) Draft Release Notes for Computing Staff

Some of these things will be applicable above DICE / LCFG layer but we'll work on it.

See also

Major Software Changes / Upgrade Differences

  • MATE is the default Desktop Environment for all uses
    • Familiar to those who used XRDP already, and for the first time replacing GNOME for local logins.
    • Users familiar with GNOME can still choose this as a default using the 'Desktop Switcher tool', aka switchdesk.
    • We intend work on Cinnamon in the longer term as a compromise.

  • SSL/TLS: DH Key size change - minimum key size as specified by OpenSSL 1.1.1 could cause issues with older services / certificates
    • #link needed#

  • Subversion: working copies must be updated using "svn update" -- at which point they will no longer work on SL7 using the default svn.
    • We've backported subversion 1.9 to SL7: use scl enable sclo-subversion19 bash or else run /opt/rh/sclo-subversion19/root/bin/svn directly.
    • TODO: add a "/usr/bin/svn-1.9" convenience link

  • Thunderbird: profiles which have been used under Ubuntu can no longer be used under SL7

  • MATE: config isn't backwards-compatible
    • It is mostly forward-compatible though, so just don't start afresh if you intend to hop between versions.

  • JetBrains IDEA and PyCharm 2020:
    • note that these now generate and store large caches in ~/.cache; keep an eye for quota issues with "power users" of either. Cache can be deleted manually as usual or possibly constrained by user preference.

  • CUDA/cuDNN
    • Note that nvidia as yet have only released cuda 11 for 20.04 and earlier versions do not support gcc 9 so initially at least only 11 will be installed.

  • /bin/sh is the dash shell
    • we're intending to revert this to bash, to match SL7

Confirmed Issues

  • Perl 5.30 segfaults when called from some embedded applications (including pidgin's perl plugins)

  • Use of the man database (man, apropos) incurs long (1-5 second) delays
    • possibly only if you extend your MANPATH with ~/ entries
    • possible we need to schedule / trigger mandb more often / at all?
    • needs the systemd timer to be enabled

  • When using <live/kerberos-keyring-ccache.h>, which we would like to consider making the default, SSH connections over GSSAPI do not use a KEYRING credentials cache (they use a FILE ccache in /tmp instead)
    • seems to be an SSH behaviour; bug report underway

  • xrdp clipboard sharing, two issues:
    • Clipboard sync works, but only with the FreeDesktop Clipboard (i.e. copy/paste). It does not work with traditional X selections (middle mouse button).
    • see also https://bugs.lcfg.org/show_bug.cgi?id=1236 - clipboard failure and other xrdp bugs due to chansrv failures
      • deploy reapchansrv as a service, to clean up stale logs immediately
      • post- reapchansrv there are still defunct chansrv procesess... "trans_check_wait_objs error resetting" amongst others in the logs. Hopefully fixed by 0.9.14

  • Some software (e.g. scenebuilder, etc.) was built hastily (by ourselves and upstream packagers!) and, though installed, might lack ease-of-use features such as freedesktop menu entries, and launchers in PATH.
    • These packages will all be fixed in due course; bugs are welcome.
    • Support may need to assist in locating these packages for users (via apt search and dpkg --listfiles) where this is the case.

  • PATH differences
    • You get a different PATH in an xrdp session than in a console or ssh session.
    • on xrdp at least (not checked others) ~/bin/share is no longer in your PATH

  • Files in the Desktop folder are not displayed on the user's desktop in Gnome, works in MATE.
    • Is this a change in behaviour?
    • Is there a standard option that needs enabling which we could document?

  • Need icon for lightdm desktop selector.

  • Installs fail on some nonrouted wires
    • nodes on Cluster416(meme) and Cluster447(landonia25) wires are failing when Downloading release files
    • The install process eventually fails with "An error has been detected while trying to use the specified Ubuntu archive mirror. Possible reasons for the error are: incorrect mirror specified; mirror is not available (possibly due to an unreliable network connection); mirror is broken (for example because an invalid Release file was found); mirror does not support the correct Ubuntu version. Additional details may be available in /var/log/syslog or on virtual console 4. Please check the specified mirror or try a different one."
    • I can't see anything obvious in syslog
    • meme will happily install if moved to wire-O

Unconfirmed Issues / Rumours / Likely Fixed by release

  • Loads of things in /etc/xdg/autostart:
    • I've added lcfg/options/disable-geoclue.h and included it in dice/options/desktop.h as this one seems particularly bad
    • but wait, there's more!
      • mate-power-manager, nm-applet, ubuntu-report-on-upgrade, update-notifier, vmware-user.desktop strike me at first glance

  • A few users have experienced openafs file corruption
    • Do we need to upgrade to 1.8.6?
    • Do we need to disable apparmor?

  • Using chrome causes the appearance of 2 authentication dialogues
    • gnome-keyring might need reset in some cases

  • a post-installation reboot seems to be required to kick everything off
    • not 100% sure if it's the reboot, or just patience required to let systemd sort everything out asynchronously

  • bashdefenv doesn't hook into VNC sessions
    • xrdp and other routes work fine; probably won't fix

  • At least two users affected by progressive slowdowns using GNOME:
    • Affected version(s) include DICE and stock Ubuntu 20.04:
    • Symptoms are exactly the same as for a machine going into "swap hell" but without the disk activity. gnome-session will be hogging the CPU and journalctl will produce lots of _onFocusChanged@resource:///org/gnome/shell/ui/closeDialog.js type messages. This seems to be a gnome bug generating lots of these messages every time focus changes and eventually overloading journald
    • Workarounds: reboot, or killall -3 gnome-shell

  • presence of a ~/.profile file makes the session chooser behave weirdly (well mine was a symlink to ~/.bprofile)

  • sudo can't acquire AFS tokens automatically, making some local root work awkward
    • we (probably) need to fix the PAM configuration to make this work.

  • Switching to console before login
    • Before logging in, with the login screen visible CTRL+ALT+F2 in SL7 used to switch to console - it would not work now before or after login.
    • I haven't been able to recreate this on any machines: I suspect a one-off installation issue.

  • xterm unicode handling different
    • I use just xterm on SL7, and run my shells and alpine in those. However on ubuntu xrdp, my xterm shells are having issues with some chars (typically quotes or apostrophes), which are fine in uxterm. Try doing "man xterm" and then searching for "unicode", around that section are quotes etc that don't display correctly for me on ubuntu xterm. From SL7 RDP I can ssh to hendry (ubuntu) and do the "man xterm" above, and the quotes appear fine. But if I start xterm from that ssh, and then do the man, they don't. - It could just be an X font thing.

Now Fixed

  • polkit changes for "disable user shutdown" might not work properly? Seems to be fine, the "shut down" option disappears from mate system menu once this policy is enabled.

  • chrome doesn't work on the XRDP service
    • related to limits.conf/as configuration; further work needed
    • removed package

  • no ispell - I noticed this because I had ispell explicitly configured in alpine. Just removing the value and using the default fixed spelling in alpine for me. So not an issue. ispell was for years just an aspell compatibility script. Now that script has been dropped from aspell. The solution is to use aspell.

  • localhost postfix - In RT 103397 user reported problems sending mail in alpine following an Ubuntu update. The issue turned out to be alpine trying to send mail via "localhost". It's unclear if this did actually work before, the user's report would suggest "yes". Indeed if you "telnet localhost 25" you get connected, but don't get an SMTP response, in fact it just sits there. Solution in this case was to just reconfigure alpine to not use "localhost". Either the empty string will work (alpine will then use sendmail from the command line) or give it an SMTP server, eg smtp.inf.ed.ac.uk/ssl. We should investigate if we want SMTP connections to localhost to work, they do on SL7.

  • mail aliases are not working with postfix - Neil has updated alias component, will be enabled everywhere by end of September

  • texlive need more packages - recommended for user env and full for RAT
    • still need to add Informatics LaTeX classes to the above

  • xscreensaver is not blanking the screen - DICE default settings are now being applied.

  • virtualbox and python2
    • We are currently using the virtualbox packages direct from Oracle, those require the python-is-python2 package
    • Ubuntu also provide virtualbox packages which are slightly older (6.1.10 rather than 6.1.12) which do not require Python 2
    • Switching would be possible but would involve an unknown amount of work.
    • Will switch but not immediately, have removed virtualbox for now to give us time to work on it.

  • Two screensavers - Remote desktop sessions are getting both xscreensaver and mate-screensaver started up. I haven't yet seen mate-screensaver actually lock the session though (cc)

  • $LESSOPEN is no longer set by default; lesspipe / filters need explicit configuration
    • we'll re-enable if there's no compelling (security?) reason not to
    • add export LESSOPEN="||/usr/bin/lesspipe %s" to a .bashrc file in the meantime

  • Pidgin won't automatically start your chat session due to misinformation from network-manager
    • launch pidgin with the -f flag
    • we'll probably rebuild pidgin in the longer-term
    • Removed network-manager packages to fix the issue.

  • some package conflicts were silently ignored by apteryx, and the packages not installed

  • Need webpic background for login screen, preferably different from SL7. fixed as of develop release, 16th Sep

-- GrahamDutton - 05 Jun 2020

Topic revision: r42 - 04 Nov 2020 - 14:16:30 - IainRae
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