For a long time now we've been advising against the use of provisioners,
but our documentation for them is pretty prominent on the website in
comparision to the better alternatives, and so it's little surprise that
many users end up making significant use of them.
Although in the longer term a change to our information architecture would
probably address this even better, this is an attempt to be explicit about
the downsides of using provisioners and to prominently describe the
alternatives that are available for common use-cases, along with some
reasons why we consider them to be better.
I took the unusual step here of directly linking to specific provider
documentation pages about the alternatives, even though we normally try
to keep the core documentation provider-agnostic, because otherwise that
information tends to be rather buried in the provider documentation and
thus the reader would be reasonable to use provisioners just because we're
not giving specific enough alternative recommendations.
In #15870 we got good feedback that it'd be more useful to have the
various filename-accepting arguments on this provisioner instead accept
strings that represent the contents of such files, so that they can be
generated from elsewhere in the Terraform config.
This change does not achieve that, but it does make room for doing this
later by renaming "minion_config" to "minion_config_file" so that we
can later add a "minion_config" option alongside that takes the file
content, and deprecate "minion_config_file".
Ideally we'd just implement the requested change immediately, but
unfortunately the release schedule doesn't have time for this so this is
a pragmatic change to allow us to make the full requested change at a
later date without backward incompatibilities.
This change is safe because the salt-masterless provisioner has not yet
been included in a release at the time of this commit.
Martin Atkins