Deployment tooling/Cabal/2015-06-08

June 8th

• Created tickets to track discussion
  • https://phabricator.wikimedia.org/T101023

• conversation between Mukunda, Bryan: possibility of using git in scap deploy by buildling local repo from core + extensions
  • Middle-step git repository for mediawiki
  • binaries/blobs?
    • might be possible with git-annex, better than git fat
    • git-torrent? might be worth further research https://github.com/cjb/GitTorrent
  • how do we handle submodules?
    • building local repo for deployment might ... ? (sorry, missed it)
  • Current services uses git via apache
    • Sometimes subjectively slow, may be room for improvement
  • Fan out
    • Preseeding, proxies needed -- could this be a post-merge jenkins job?
  • Deploy master node
    • Currently always tin
    • Could  start deploy from other proxies (pre-seed target)
    • Agnosticly built in terms of proxies vs pre-seed target
  • Might be good time to experiment with git based transport
    • Determine whether it's going to be over ssh/https/torrent/etc.
    • Run tests outside of prod to determine if feasible for MW
    • nginx/varnish, something, in each datacenter for fanout proxy
  • less clobbering
  • New work_dir after fetch with filecheckout

• Moving git blobs solutions
  • Git large file store https://git-lfs.github.com/

  *** Pros:   **** Scalable: github uses it   **** Supported: seems to be developed and supported by some of the core git team

• • Git Annex
  • GitTorrent
  • Git Fat
  • Criteria:

    *** Reliability (should check out the actual file not just text of sha)     *** Flexibility of transport mechanism     *** Scalability and reprudicibiliity (scales up and down)     *** Resource consuption      **** CPU     **** Limit network IO     **** Limit disk IO     *** Speed     *** Could possibly simulate cross-datacenter limitations with `tc`     *** eqiad - codfw RTT ~40ms, inside eqiad RTT is ~0.5ms

• Definitions of success
  • Atomic failure modes
  • Optional fanout proxies based on git-http(s)
  • Blobs pused around with git annex or another solution (GitTorrent, large file store, figure out criteria for solution)
  • Continuous feedback to user
  • Verify integrity of repo
  • Not insanely slow (any slower than current system)

To use staging for deployment blob mechanisms