Ok, here’s a quick one.

I recently had the Ubuntu upgrade popup kick in on my desktop computer, prompting me to upgrade to Ubuntu 20.04. It was a rainy afternoon, so I went ahead.

Things seemed to go fine (even my dual screen Nvidia setup worked), but I could no longer log in from either the desktop or ssh. The local root account was fine, but none of the network users could log in.

So, this was an NIS / ypbind problem.

I logged in as root and ran ypwhich, which reported it could not connect to ypbind. However, networking was working, and I could ping the NIS server.

Running /etc/init.d/nis restart didn’t do anything, but when I ran ypbind manually, all of a sudden I was able to log in.

Ubuntu likes to change their startup scripts as often as politicians like to change their faces, so I wasn’t overly surprised. Most likely the startup order had changed, and maybe NIS was being brought up before networking was initialised.

My quick and dirty solution

Ok, so I’m getting old, and I don’t enjoy this as much as I once did. I’d rather not spend the entire day deep in the bowls of upstart or systemd or whatever the new thing Ubuntu is using today.

So, this isn’t the correct solution, but it works.

  1. Log in as root
  2. Edit the crontab: crontab -e
  3. Add this line: @reboot /usr/sbin/ypbind &

Save and reboot, and you should be able to log in.

Yes, I know this is dirty, but honestly life is too short!

I hit a number of gotchas when upgrading my home and business web server from jessie to stretch, here they are in no particular order. Hopefully will save you some hair pulling…

Broken MariaDB install

Debian now ships with MariaDB by default, but when I upgraded mariadb-server would not install, meaning their were loads of broken dependencies. Dpkg exited with an error status, but with no indication as to what the actual error actually was.

Fixes suggested elsewhere (purging and reinstalling, moving /var/lib/mysql away and reinstalling, etc) did not help.

Eventually, I was able to manually execute mysql_install_db, which actually gave me some output. For me, the problem seemed to have been caused by the slow query logging entries, which are either unsupported in MariaDB or are named something else (I’ve not had a chance to check).

I commented out the following lines as follows:

… and apt-get was able to install the package.

Isolated /tmp

The version of systemd shipping with Debian 9 includes some security enhancements, including PrivateTmp, which isolates the temporary directory from users.

So, if you use your tmp directory to store e.g. cache data when developing websites, you’re going to need to store this somewhere else, otherwise file_exists and other file functions will not be able to read or write to them.

PHP 7

Ooooooo… boy.

Biggest hitter by far for me was that Debian 9 now ships with PHP7. Usefully, 5.6 is still available, so you have to switch to 7 manually (which means installing all the appropriate module again). Gotcha here is the mysql extension has been entirely removed, good thing too… however, if you’ve been running your server for a while like I have, you’re going to have a metric shittonne of things that need to be upgraded in order to work. Biggest pain in the bum was my ownCloud 8 server (made harder by the fact you can’t cross major versions in an upgrade, and the releases for those versions were no longer available until I nudged someone on IRC, also, pro tip, do the upgrade on PHP 5).

For scripts that either don’t have newer versions, or legacy stuff you don’t have time right now to allocate significant dev resources to, there is a mysql->mysqli shim available. This seems to work quite well in most cases, although of course it should be fairly high priority for you to migrate to PDO or similar!

Elgg and PHP 7

If you’re building sites on the 1.x.x branch of Elgg, you’re either going to have to upgrade to Elgg 2.x to run on PHP7, or use the shim.

I only have development sites running on PHP 7 at the moment, all of my clients that use < Elgg 2 are running on older PHP releases for now, but the shim works well in development and until I can manage those upgrades. If you use the shim you may need to comment out the following lines in executeQuery() in engine/classes/Elgg/Database.php:

…since the resource returned by the shim is a different type than expected.

That’s all so far, hope this will save you some stress!

I recently upgraded my webserver to Debian Jessie, which included an upgrade for Apache and PHP. This resulted in a few gotchas…

Mod_python and WSGI don’t play nicely

See my previous post on the subject…

Some PHP extensions not installed

Some PHP extensions didn’t seem to be automatically upgraded/reinstalled (these may have been ones previously only available through PECL), so:

New permissions

Apache 2.4 uses a different permissions (access / deny) arrangement than before, so you need to change these over.

So for example, where you have:

You’d now have:

Apache have a good guide here.

Random crashes with XCache

If you have XCache installed, you might start getting random crashes, often with an error about:

PHP Fatal error: Cannot redeclare class ...

This is caused because the installer installs and activates the Zend Opcache module automatically, and you can’t run two opcode caches safely.