Our 4 MediaWiki clusters, `application`, `api`, `jobrunners/videoscalers`, `parsoid` need to be migrated to Debian Buster.
Provisional plan for the migration:
[x] Upgrade all current **stretch** servers to ICU 63 T264991
[x] Rebuild all our php-7.2 packages for Debian Buster (buster-wikimedia)
[x] php7.2-cli
[x] php7.2-common
[x] php7.2-curl
[x] php7.2-dba
[x] php7.2-fpm
[x] php7.2-gd
[x] php7.2-gmp
[x] php7.2-mysql
[x] php7.2-opcache
[x] php7.2-phpdbg
[x] php7.2-readline
[x] php7.2-xml
[x] Build missing packages for Buster
[x] ploticus
[x] prometheus-nutcracker-exporter
[x] prometheus-php-fpm-exporter
[x] Fix puppet code to support Buster
[x] ttf-alee replaced with fonts-alee
[x] ttf-wqy-zenhei replaced with fonts-wqy-zenhei
[x] code to add PHP72 component on buster
[x] Reimage mwdebug1001 to buster OR introduce mwdebug1003, so not to mess with development testing
[x] first iteration done with testvm1001, decom'ed again
[x] mwdebug1003 to be introduced early December
[x] add PHP72 APT component on mwdebug1003
[] Reimage parse2001 to buster (parsoid)
[] Reimage mw2243 to buster (jobrunner)
**Q3**
[] ensure https://gerrit.wikimedia.org/r/c/operations/puppet/+/445604 has been merged
[] ensure php72 component gets installed on all buster servers https://gerrit.wikimedia.org/r/c/operations/puppet/+/642073
[] Reimage `api` canaries
[] Reimage `appserver` canaries
[] Reimage `parsoid` canaries T268524
[] Reimage `jobrunner/videoscaler` canaries
[] Reimage/migrate mwmain1002
[] Mark all special servers in our clusters (scap proxies, mcrouter proxies)
[] Reimage All clusters (add ertherpad link with list of servers)