There are a few situations that we've seen arise quite commonly for folks
upgrading from Terraform 0.11 to 0.12. These particular problems are not
things that Terraform 0.12 can fix automatically during upgrading, but
we can at least give some better feedback to users that they ought to be
addressed _before_ upgrading.
The provider address problem is already detected and flagged by the
"terraform 0.11checklist" command that folks should run as part of their
upgrade process, but the module address problem is not something we
noticed was lacking validation in 0.11 and so the checklist tool doesn't
cover it. Due to the lack of coverage in the checklist tool, this commit
also includes an additional section in the upgrade guide that mentions
the problem and gives instructions on how to address it.
The state refactoring command "terraform state mv" in Terraform 0.11 does
not update existing dependency addresses recorded in the state when it
moves objects around, and Terraform only updates the dependency addresses
in the state when it performs a full update on a resource instance, and
so it's a common problem for folks updating from Terraform 0.11 with
resource names that are not valid identifiers to run into state upgrade
errors even though they have followed the instructions produced by
"terraform 0.12checklist".
Dependencies are synced from config during every refresh walk anyway, so
in practice we can get away with just discarding invalid dependency
addresses and letting the refresh walk update them. In practice these
addresses are unlikely to be pointing at a resource that actually exists
anyway, because if so Terraform 0.12's configuration parser wouldn't be
able to interpret it.
Discarding invalid dependency addresses allows the state upgrade to
complete successfully in such cases and thus gives the refresh step an
opportunity to repair the problem.
The CreateBeforeDestroy transformer correctly handles the edge referred
to in the comment, and going forward it will probably be easier to use
the knowledge of this edge for CBD anyway.
A number of tests had no, or incomplete state for the transformations
they wanted to test. Add states state with the correct dependencies for
these tests.
An earlier change to eliminate the large amount of duplicate edges being
added by the original CreateBeforeDestroy dependency mapper mistakingly
prevented adding edges when there are multiple CBD dependencies.
This updates the algorithm to use a map to collect all possible edges
and de-deplucating them before processing.
Some of our warnings are produced in response to particular configuration
constructs which might appear many times across a Terraform configuration.
To avoid the warning output dwarfing all of the other output, we'll use
ConsolidateWarnings to limit each distinct warning summary to appear at
most twice, and annotate the final one in the sequence with an additional
paragraph noting that some number of them have been hidden.
This is intended as a compromise to ensure that these warnings are still
seen and noted but to help ensure that we won't produce so many of them
as to distract from other output that appears alongside them.
This applies only to warnings relating to specific configuration ranges;
errors will continue to be shown individually, and sourceless warnings
(which are rare in Terraform today) will likewise remain ungrouped because
they are less likely to be repeating the same statement about different
instances of the same problem throughout the configuration.
This detects when there are many warning diagnostics with the same summary
and consolidates some of them together into a single diagnostic in order
to make the resulting output less overwhelming when presented in CLI
output where other information is competing for attention with the
warnings.
This is not yet used anywhere. Usage of it will follow in a subsequent
commit.
EvalRefreshDependencies is used to update resource dependencies when
they don't exist, allow broken or old states to be updated. While
appending any newly found dependencies is tempting to have the largest
set available, changes to the config could conflict with the prior
dependencies causing cycles.
Since a create node cannot both depend on its destroy node AND be
CreateBeforeDestroy, the same goes for its dependencies. While we do
connect resources with dependency destroy nodes so that updates are
ordered correctly, this ordering does not make sense in the
CreateBeforeDestroy case.
If resource node is CreateBeforeDestroy, we need to remove any direct
dependencies from it to destroy nodes to prevent cycles. Since we don't
know for certain if a crate node is going to be CreateBeforeDestroy at
the time the edge is added in the graph, we add it unconditionally and
prune it out later on. The pruning happens during the CBD transformer
when the CBD destroy node reverses it's own destroy edge. The reason
this works for detecting the original edge, is that dependencies of CBD
resources are forced to be CBD themselves. This does have a false
positive where the case of the original node is NOT CBD, but this can be
taken care of later when we gather enough information in the graph to
prevent the connection in the first place.
Martin Atkins