Indians team president Chris Antonetti confirmed Armstrong would be included on the club's Opening Day roster, MLB.com's Jordan Bastian reports.
The Indians had four pitchers competing for the final bullpen spot that was up for grabs, with Armstrong beating out Kyle Crockett, Carlos Frias and Nick Goody for those honors. Armstrong is expected to fill a lower-leverage role for the Indians and won't have an easy path to holds with Andrew Miller and Bryan Shaw firmly entrenched as the top two options in the bridge to closer Cody Allen.