A resource can be imported by setting the `import` property in the
resource options bag when instantiating a resource. In order to
successfully import a resource, its desired configuration (i.e. its
inputs) must not differ from its actual configuration (i.e. its state)
as calculated by the resource's provider.
There are a few interesting state transitions hiding here when importing
a resource:
1. No prior resource exists in the checkpoint file. In this case, the
resource is simply imported.
2. An external resource exists in the checkpoint file. In this case, the
resource is imported and the old external state is discarded.
3. A non-external resource exists in the checkpoint file and its ID is
different from the ID to import. In this case, the new resource is
imported and the old resource is deleted.
4. A non-external resource exists in the checkpoint file, but the ID is
the same as the ID to import. In this case, the import ID is ignored
and the resource is treated as it would be in all cases except for
changes that would replace the resource. In that case, the step
generator issues an error that indicates that the import ID should be
removed: were we to move forward with the replace, the new state of
the stack would fall under case (3), which is almost certainly not
what the user intends.
Fixes#1662.
* Add a list of in-flight operations to the deployment
This commit augments 'DeploymentV2' with a list of operations that are
currently in flight. This information is used by the engine to keep
track of whether or not a particular deployment is in a valid state.
The SnapshotManager is responsible for inserting and removing operations
from the in-flight operation list. When the engine registers an intent
to perform an operation, SnapshotManager inserts an Operation into this
list and saves it to the snapshot. When an operation completes, the
SnapshotManager removes it from the snapshot. From this, the engine can
infer that if it ever sees a deployment with pending operations, the
Pulumi CLI must have crashed or otherwise abnormally terminated before
seeing whether or not an operation completed successfully.
To remedy this state, this commit also adds code to 'pulumi stack
import' that clears all pending operations from a deployment, as well as
code to plan generation that will reject any deployments that have
pending operations present.
At the CLI level, if we see that we are in a state where pending
operations were in-flight when the engine died, we'll issue a
human-friendly error message that indicates which resources are in a bad
state and how to recover their stack.
* CR: Multi-line string literals, renaming in-flight -> pending
* CR: Add enum to apitype for operation type, also name status -> type for clarity
* Fix the yaml type
* Fix missed renames
* Add implementation for lifecycle_test.go
* Rebase against master
