Xml/sql dumps and MediaWiki-Vagrant, two great tastes that taste great together?

Problems, problems, problems

Recently a colleague asked me to look over a patchset in gerrit that would add some new functionality to a set of weekly dumps, and, as is my wont, I asked if he’d tested the patch. The answer was, “Well, no, just parts of it”. When I dug into the issue a little deeper, it turned out that the reason the script hadn’t been tested is that there was no easy way to do so!

Enter MediaWiki-Vagrant. [1] This lets you set up a virtual machine on your laptop with the latest and greatest version of MediaWiki. By the simple application of puppet roles, you can add multiple wikis and your own skeletal copy of Wikidata for testing. This seemed like the perfect place to add a dumps role.

Adam Wight started working on such a role in April of 2017. [2] We’re all busy people so it took a while, but finally a few weeks ago the role was merged. It lets the user do a basic test of the xml/sql dumps against whatever’s in the master branch of MediaWiki. But it doesn’t allow my colleague to test his script changes. That, it turns out, is complicated.

So, without further ado, here is what I did in order to get tests up and running in a setup that permits xml/sql dumps to run, as well as tests of ‘miscellaneous’ dump scripts such as category dumps or the ‘Wikidata weeklies’.

MediaWiki-Vagrant on Fedora

Fedora is my distro of choice, so there was special prep work for the installation of MediaWiki-Vagrant.

1. I needed libvirt and lxc; I got these by

dnf install vagrant, vagrant-libvirt, vagrant-lxc, vagrant-lxc-doc,
   lxc-libs, lxc, lxc-templates, lxc-extra, nfs-utils redir

2. added myself to the /etc/sudoers file:

meeee ALL=(ALL) ALL

3. edited /etc/lxc/default.conf:

#lxc.network.link = lxcbr0
lxc.network.link = virbr0

4. fixing up the firewall:

firewall-cmd --permanent --zone public --add-port=20048/udp
firewall-cmd --permanent --zone public --add-port=111/udp
firewall-cmd --permanent --zone public --add-port=2049/udp
firewall-cmd --permanent --zone public --add-service mountd
firewall-cmd --permanent --zone public --add-service rpc-bind
firewall-cmd --permanent --zone public --add-service nfs
firewall-cmd --reload

and checking that nfs was indeed in the list by:

firewall-cmd --list-all

5. set up udp for v3, which is vagrant default but is turned off by default in Fedora; this was done by editing /etc/sysconfig/nfs
and changing this line

RPCNFSDARGS=""

RPCNFSDARGS="--udp"

then restarting the service:

service nfs-server restart

Installing MediaWiki-Vagrant

This was slightly different than the instructions [3], since I’m using the lxc provider.

git clone --recursive https://gerrit.wikimedia.org/r/mediawiki/vagrant
cd vagrant
vagrant config --required (I just just left the name blank at the prompt)
vagrant up --provider lxc --provision

Provisioning the Wikidata role

The Wikidata role needs some special handling. [4] But it needs even more specialness than the docs say. There’s an issue with the Wikibase extension’s composer setup that we need to work around. [5] Here’s all the steps involved.

vagrant git-update
vagrant ssh

These steps are all done from within the VM:

sudo apt-get update
sudo apt-get upgrade
composer selfupdate --update-keys (and enter the keys from https://composer.github.io/pubkeys.html)
composer config --global process-timeout 9600

Get off the vm, and then:

vagrant roles enable wikidata
vagrant provision

This last fails badly, failing to find a certain class and so everything breaks. Edit {code>mediawiki/composer.local.json and add the line

"extensions/Wikibase/composer.json"

to the merge-plugin include stanza at the end of the file. Now you can rerun composer and the failed steps:

vagrant ssh
cd /vagrant/mediawiki
rm composer.lock
composer update --lock
sudo apachectl restart
sudo -u www-data \(cd /vagrant/mediawiki; /usr/local/bin/foreachwiki 
    update.php --quick --doshared \)

Import some data!

At this point the installation was working but there was only the Main Page in Wikidatawiki. I needed to get some data in there.

I grabbed the first so many pages from one of the wikidata dumps (~170 pages), put them in an xml file, added a ” tag on the end, and put that in srv/wikidata_pages.xml.

Next I needed to enable entity imports, which is done by creating the file /vagrant/settings.d/wikis/wikidatawiki/settings.d/puppet-managed/10-Wikidata-entities.php with the contents:

<?php 
  $wgWBRepoSettings['allowEntityImport'] = true;

Next came the import:

cd /vagrant
cat /vagrant/srv/wikidata_pages.xml | sudo -u www-data mwscript importDump.php
    --wiki=wikidatawiki --uploads --debug --report 10

This took a lot longer than expected (30 minutes for about 170 pages) but did eventually complete without errors. Then some rebuilds:

sudo -u www-data mwscript rebuildrecentchanges.php --wiki=wikidatawiki
sudo -u www-data mwscript initSiteStats.php --wiki=wikidatawiki

Provisioning the dumps role

At last I could cherry-pick my gerrit change [6]. But because by default I’m using nfs on linux for the mount of /vagrant inside the VM, I needed to add some tweaks that let puppet create some directories in /vagrant/srv owned by the dumps user.

In /vagrant, I created the file Vagrantfile-extra.rb with the following contents:

mwv = MediaWikiVagrant::Environment.new(File.expand_path('..', __FILE__))
settings = mwv.load_settings

Vagrant.configure('2') do |config|
  if settings[:nfs_shares]
    root_share_options = { id: 'vagrant-root' }
    root_share_options[:type] = :nfs
    root_share_options[:mount_options] = ['noatime', 'rsize=32767', 'wsize=32767', 'async']
    root_share_options[:mount_options] << 'fsc' if settings[:nfs_cache]
    root_share_options[:mount_options] << 'vers=3' if settings[:nfs_force_v3]
    root_share_options[:linux__nfs_options] = ['no_root_squash', 'no_subtree_check', 'rw', 'async']
    config.nfs.map_uid = Process.uid
    config.nfs.map_gid = Process.gid
    config.vm.synced_folder '.', '/vagrant', root_share_options
  end
end

Then I needed to restart the VM so that the freshly nfs-mounted share would permit chown and chmod from within it:

vagrant halt
vagrant up --provider lxc --provision

After that, I was able to enable the dumps role:

vagrant roles enable dumps
vagrant provision

Wikidata dump scripts setup

Next I had to get all the scripts needed for testing, by doing the following:

copy into /usr/local/bin: dumpwikidatajson.sh, dumpwikidatardf.sh, wikidatadumps-shared.sh [7]
copy into /usr/local/etc: dump_functions.sh dcatconfig.json [7]
copy a fresh clone of operations-dumps-dcat into /usr/local/share [8]

And finally, I had to fix up a bunch of values in the dump scripts that are meant for large production wikis.
In dumpwikidatardf.sh:

shards=2
dumpNameToMinSize=(["all"]=`expr 2350 / $shards` ["truthy"]=`expr 1400 / $shards`)

in dumpwikidatajson.sh:

shards=1
if [ $fileSize -lt `expr 20 / $shards` ]; then

in wikidatadumps-shared.sh:

pagesPerBatch=10

and as root, clean up some cruft that has the wrong permissions:

rm -rf /var/cache/mediawiki/*

Running dumps!

For xml/sql dumps:

su -  dumpsgen
cd /vagrant/srv/dumps/xmldumps-backup
python worker.py --configfile /vagrant/srv/dumps/confs/wikidump.conf.dumps [name_of_wiki_here]

Some wikis available for ‘name_of_wiki_here’ are: enwiki, wikidatawiki, ruwiki, zhwiki, among others.

For wikidata json and rdf dumps:

su - dumpsgen
mkdir /vagrant/srv/dumps/output/otherdumps/wikidata/
/usr/local/bin/dumpwikidatajson.sh
/usr/local/bin/dumpwikidatardf.sh all ttl
/usr/local/bin/dumpwikidatardf.sh truthy nt

See how easy that was? 😛 😛

But seriously, folks, we are working on making testing all dumps easy, or at least easier. This brings us one step closer.

Next steps

It’s a nuisance to edit the scripts and change the number of shards and so on; these are being turned into configurable values. A special configuration file will be added to the dumps role that all ‘miscellaneous dumps’ can use for these sorts of values.

It’s annoying to have to copy in the scripts from the puppet repo before testing. We’re considering creating a separate repository operations/dumps/otherdumps which would contain all of these scripts; then a simple ‘git clone’ right from the dumps role itself would add the scripts to the VM.

There are multiple symlinks of the directory containing the php wrapper MWScript.php to different locations, because several scripts expect the layout of the mediawiki and related repos to be the way it’s set up in production. The location should be configurable in all scripts so that it can bepassed in on the command line for testing, and the extra symlinks removed from the dumps role.

The composer workaround will eventually be unnecessary once Wikibase has been fixed up to work with composer the way many MediaWiki extensions do. That’s on folks’ radar already.

The xml file of pages to import into wikidata could be provided in the dumps role and entity imports configured, though the import itself might still be left for the user because it takes so long.

Once the above fixes are in, we’ll probably be starting to move to kubernetes and docker for all testing. 😀

Thanks!

Thanks to: Adam Wight for all the work on the initial dumps role, Stas Malyshev for the composer solution and for being a guinea pig, and the creators and maintainers of MediaWiki-Vagrant for making this all possible.

apergos' open musings