When TerraForm is used to configure and deploy infrastructure
applications that require dozens templated files, such as Kubernetes, it
becomes extremely burdensome to template them individually: each of them
requires a data source block as well as an upload/export (file
provisioner, AWS S3, ...).
Instead, this commit introduces a mean to template an entire folder of
files (recursively), that can then be treated as a whole by any provider
or provisioner that support directory inputs (such as the
file provisioner, the archive provider, ...).
This does not intend to make TerraForm a full-fledged templating system
as the templating grammar and capabilities are left unchanged. This only
aims at improving the user-experience of the existing templating
provider by significantly reducing the overhead when several files are
to be generated - without forcing the users to rely on external tools
when these templates stay simple and that their generation in TerraForm
is justified.
The template resources don't actually need to retain any state, so they
are good candidates to be data sources.
This includes a few tweaks to the acceptance tests -- now configured to
run as unit tests -- since it seems that they have been slightly broken
for a while now. In particular, the "update" cases are no longer tested
because updating is not a meaningful operation for a data source.
Quentin Machu