Previously we would only ever add new lock entries or update existing
ones. However, it's possible that over time a module may _cease_ using
a particular provider, at which point we ought to remove it from the lock
file so that operations won't fail when seeing that the provider cache
directory is inconsistent with the lock file.
Now the provider installer (EnsureProviderVersions) will remove any lock
file entries that relate to providers not included in the given
requirements, which therefore makes the resulting lock file properly match
the set of packages the installer wrote into the cache.
This does potentially mean that someone could inadvertently defeat the
lock by removing a provider dependency, running "terraform init", then
undoing that removal, and finally running "terraform init" again. However,
that seems relatively unlikely compared to the likelihood of removing
a provider and keeping it removed, and in the event it _did_ happen the
changes to the lock entry for that provider would be visible in the diff
of the provider lock file as usual, and so could be noticed in code
review just as for any other change to dependencies.
This makes it match some incoming links we have elsewhere, but also it
makes the heading a bit more consice because "module" isn't really adding
anything here anyway: input variables are _always_ in modules.
As explained in the changes: The 'enhanced' backend terminology, which
only truly pertains to the 'remote' backend with a single API (Terraform
Cloud/Enterprise's), has been found to be a confusing vestige which need
only be explained in the context of the 'remote' backend.
These changes reorient the explanation(s) of backends to pertain more
directly to their primary purpose, which is storage of state snapshots
(and not implementing operations).
That Terraform operations are still _implemented_ by the literal
`Backend` and `Enhanced` interfaces is inconsequential a user of
Terraform, an internal detail.
This is documentation for the first set of refactoring-related features,
all based on the new "moved" blocks in the Terraform language.
I've named the documentation section "refactoring" because in previous
discussions with users that seems to be the term they use to describe the
underlying need.
"moved" blocks are our first language feature intended to meet that need,
although it probably won't be the last as we consider other requirements
in later releases. My intent here is that once we've published this it
should eventually end up being the first result for a web search for the
topic of Terraform refactoring.
Laura Pacilio