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.
Most CBD-related cycles include destroy nodes, and destroy nodes were
all being pruned from the graph before staring the Validate walk.
In practice this meant that we had scenarios that would error out with
graph cycles on Apply that _seemed_ fine during Plan.
This introduces a Verbose option to the GraphBuilder that tells it to
generate a "worst-case" graph. Validate sets this to true so that cycle
errors will always trigger at this step if they're going to happen.
(This Verbose option will be exposed as a CLI flag to `terraform graph`
in a second incoming PR.)
refs #1651
