Engines
An engine is the program responsible for executing run commands like plan and apply. OTF provides support for two engines:
terraformtofu
The default engine is terraform. This can be overridden with the otfd flag --default-engine.
Warning
If you're running more than one instance of otfd, take care to set this flag to the same value on each instance. Doing otherwise will lead to unpredictable results.
When you create a workspace, it'll use the default engine. You can override the engine for a workspace in its settings.
When you create a run OTF will download the workspace's engine if it hasn't already been downloaded. The engine binaries are downloaded to the directory specified by the flag --engine-bins-dir.