We no longer need special cases for most things during a full destroy,
so remove those from the graph transformations.
The only remaining cases are:
- remove the root outputs, so destroy ends up with a clean state
- reverse the target deps when targeting a destroy.
Start by removing the DestroyEdge type altogether. This is only used to
detect the natural edge between a resource's create and destroy nodes,
but that's not necessary for any transformations. The custom edge type
also interferes with normal graph manipulations, because you can't
delete an arbitrary edge without knowing the type, so deletion of the
edge based only on the endpoints is often done incorrectly. The dag
package itself does this incorrectly in TransitiveReduction, which
always assumes the BasicEdge type.
Now that inter-resource destroy dependencies are already connected in the
DestroyEdgeTransformer (from the stored deps in state), there's no need
to search out all dependant resources in the CBD transformation, as they
should all be connected. This makes the CBD transformation rule quite
simple: reverse any edges from create nodes.
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.
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.
The CBDEdgeTransformer tests worked on fake data structures, with a
synthetic graph, and configs that didn't match. Update them to generate
a more complete graph, with real node implementations, from real
configs.
The output graph is filtered down to instances, and the results still
functionally match the original expected test results, with some minor
additions due to using the real implementation.
When looking for dependencies to fix when handling
create_before_destroy, we need to look past more than one edge, as
dependencies may appear transitively through outputs and variables. Use
Descendants rather than UpEdges.
We have the full graph to use for the CBD transformation, so there's no
longer any need to create a temporary graph, which may differ from the
original.
Comment out an out of date CBD test. The test no longer works due to
the CBD status being checked during plan, but the test case may still
have some value which we can review later.
update the text in the CBD transformer to reflect the
s/ancestor/descendent/ change.
Previously we used a single plan action "Replace" to represent both the
destroy-before-create and the create-before-destroy variants of replacing.
However, this forces the apply graph builder to jump through a lot of
hoops to figure out which nodes need it forced on and rebuild parts of
the graph to represent that.
If we instead decide between these two cases at plan time, the actual
determination of it is more straightforward because each resource is
represented by only one node in the plan graph, and then we can ensure
we put the right nodes in the graph during DiffTransformer and thus avoid
the logic for dealing with deposed instances being spread across various
different transformers and node types.
As a nice side-effect, this also allows us to show the difference between
destroy-then-create and create-then-destroy in the rendered diff in the
CLI, although this change doesn't fully implement that yet.
Due to how often the state and plan types are referenced throughout
Terraform, there isn't a great way to switch them out gradually. As a
consequence, this huge commit gets us from the old world to a _compilable_
new world, but still has a large number of known test failures due to
key functionality being stubbed out.
The stubs here are for anything that interacts with providers, since we
now need to do the follow-up work to similarly replace the old
terraform.ResourceProvider interface with its replacement in the new
"providers" package. That work, along with work to fix the remaining
failing tests, will follow in subsequent commits.
The aim here was to replace all references to terraform.State and its
downstream types with states.State, terraform.Plan with plans.Plan,
state.State with statemgr.State, and switch to the new implementations of
the state and plan file formats. However, due to the number of times those
types are used, this also ended up affecting numerous other parts of core
such as terraform.Hook, the backend.Backend interface, and most of the CLI
commands.
Just as with 5861dbf3fc49b19587a31816eb06f511ab861bb4 before, I apologize
in advance to the person who inevitably just found this huge commit while
spelunking through the commit history.
Add a graphNodeAttachDestroy interface, so destroy nodes can be attached
to their companion create node. The creator can then reference the
CreateBeforeDestroy status of the destroyer, determining if the current
state needs to be replaced or deposed.
This is needed when a node is forced to become CreateBeforeDestroy by a
dependency rather than the config, since because the config is
immutable, only the destroyer is aware that it has been forced
CreateBeforeDestroy.
Previously we fetched schemas during the AttachSchemaTransformer,
potentially multiple times as that was re-run for each graph built. Now
we fetch the schemas just once during context construction, passing that
result into each of the graph builders.
This only addresses the schema accesses during graph construction. We're
still separately loading schemas during the main walk for evaluation
purposes. This will be addressed in a later commit.
These transformers both construct temporary graphs using many of the same
transformers used in the apply graph, and properly doing this now requires
access to the providers and provisioners in order to obtain their schemas.
Along with this, we also update the tests here to use the
simpleMockComponentFactory helper to get a mock provider with a schema
already configured, which means we also need to update the test fixtures
and assertions to use the resource type and attributes defined in that
mock factory.
Due to how deeply the configuration types go into Terraform Core, there
isn't a great way to switch out to HCL2 gradually. As a consequence, this
huge commit gets us from the old state to a _compilable_ new state, but
does not yet attempt to fix any tests and has a number of known missing
parts and bugs. We will continue to iterate on this in forthcoming
commits, heading back towards passing tests and making Terraform
fully-functional again.
The three main goals here are:
- Use the configuration models from the "configs" package instead of the
older models in the "config" package, which is now deprecated and
preserved only to help us write our migration tool.
- Do expression inspection and evaluation using the functionality of the
new "lang" package, instead of the Interpolator type and related
functionality in the main "terraform" package.
- Represent addresses of various objects using types in the addrs package,
rather than hand-constructed strings. This is not critical to support
the above, but was a big help during the implementation of these other
points since it made it much more explicit what kind of address is
expected in each context.
Since our new packages are built to accommodate some future planned
features that are not yet implemented (e.g. the "for_each" argument on
resources, "count"/"for_each" on modules), and since there's still a fair
amount of functionality still using old-style APIs, there is a moderate
amount of shimming here to connect new assumptions with old, hopefully in
a way that makes it easier to find and eliminate these shims later.
I apologize in advance to the person who inevitably just found this huge
commit while spelunking through the commit history.
Ensure that each instance of BasucGraphBuilder gets a name corresponding
to the Builder which created it. This allows us to differentiate the
graphs in the logs.
