Use the new StateLocker field to provide a wrapper for locking the state
during terraform.Context creation in the commands that directly
manipulate the state.
Simplify the use of clistate.Lock by creating a clistate.Locker
instance, which stores the context of locking a state, to allow unlock
to be called without knowledge of how the state was locked.
This alows the backend code to bring the needed UI methods to the point
where the state is locked, and still unlock the state from an outer
scope.
Provide a NoopLocker as well, so that callers can always call Unlock
without verifying the status of the lock.
Add the StateLocker field to the backend.Operation, so that the state
lock can be carried between the different function scopes of the backend
code. This will allow the backend context to lock the state before it's
read, while allowing the different operations to unlock the state when
they complete.
Shell tab completion for all of the subcommands under
"terraform workspace", providing the appropriate kind of auto-complete for
each argument, along with completion for for any flags.
We're shifting terminology from "environment" to "workspace". This takes
care of some of the main internal API surface that was using the old
terminology, though is not intended to be entirely comprehensive and is
mainly just to minimize the amount of confusion for maintainers as we
continue moving towards eliminating the old terminology.
Feedback after 0.9 was that the term "environment" was confusing due to
it colliding with several other concepts, such as OS environment
variables, a non-aligned Terraform Enterprise concept, and differing ideas
of "environment" within various organizations.
This new term "workspace" is intended to ease some of that confusion. This
term is not used anywhere else in Terraform today, and we expect it to not
be used in a manner that would be confusing within user organizations.
This begins a deprecation cycle for the "terraform env" family of commands,
instead moving to an equivalent set of "terraform workspace" commands.
There are some remaining references to the old "environment" concept in
the code, which will be cleaned up in a separate change. This change is
instead focused on text visible in the UI and wording within code comments
for the benefit of human maintainers of the code.
James Bardin