During the input walk we stash the values resulting from user input
(if any) in the eval context for use when later walks need to resolve
the provider config.
However, this repository of input results is only able to represent
literal values, since it does not retain the record of which of the keys
have values that are "computed".
Previously we were blindly stashing all of the results, failing to
consider that some of them might be computed. That resulted in the
UnknownValue placeholder being misinterpreted as a literal value when
the data is used later, which ultimately resulted in it clobbering the
actual expression evaluation result and thus causing the provider to
fail to configure itself.
Now we are careful to only retain in this repository the keys whose values
are known statically during the input phase. This eventually gets merged
with the dynamic evaluation results on subsequent walks, with the dynamic
keys left untouched due to their absence from the stored input map.
This fixes#11264.
Currently Terraform is leaking goroutines and with that memory. I know
strictly speaking this maybe isn’t a real concern for Terraform as it’s
mostly used as a short running command line executable.
But there are a few of us out there that are using Terraform in some
long running processes and then this starts to become a problem.
Next to that it’s of course good programming practise to clean up
resources when they're not needed anymore. So even for the standard
command line use case, this seems an improvement in resource management.
Personally I see no downsides as the primary connection to the plugin
is kept alive (the plugin is not killed) and only unused connections
that will never be used again are closed to free up any related
goroutines and memory.
The provider config was not being properly merged across module
boundaries during the Input walk over the graph, so when a provider was
configured at the top level, resources in modules could improperly
trigger a request for input for a provider attribute that's already
defined.
/cc @sethvargo
Prior to this commit, we'd only persist the result of calling Input if
any input was given (len(result) > 0). The result was that every module
would also repeat asking for input even if there was no input to be
asked for.
This commit makes it so that if no input was received, we still set a
sentinel so that modules don't re-ask.
Martin Atkins