Normally, the order of the Astros rotation wouldn't be something postworthy, but since the Rangers are facing the Astros in the first series of the year, I figure it is worth mentioning, so we know who Texas will be facing.
Per Brian McTaggart on Twitter, Astros manager Bo Porter has named Bud Norris as his Opening Day starter. Lucas Harrell will pitch game two of the season, and Philip Humber will pitch game three.
The Rangers' rotation for the start of the season is still unannounced. Either Yu Darvish or Matt Harrison will pitch the opener, and the one who doesn't pitch on Opening Day will start game two. The game three starter hasn't been announced, but I would assume at this point that it will be Derek Holland, with Alexi Ogando being the fourth starter and a pitcher to be determined (likely either Nick Tepesch or Robbie Ross) as the #5 starter.