In the old remote state system we had the idea of a local backup, which
is actually still present for the legacy backends but no longer applies
for the new-style backends like the s3 backend.
It's problematic when an apply runs for long enough that someone's
time-limited AWS STS credentials expire and then Terraform fails and can't
persist state to S3.
To reduce the risk of lost state, here we add some extra fallback code
for the local apply operation in particular. If either state writing
or state persisting fail then we attempt to write the state to a special
backup file errored.tfstate, and produce an error message that guides the
user on how to retry uploading this state.
In the unlikely event that we can't write to local disk either (e.g.
permissions problems) we take a last-ditch attempt to dump the JSON onto
stdout and advise the user to manually copy it into a file for import.
If even that doesn't work for some reason, we assume a critical Terraform
bug (JSON-serialization problem with states?) and bail out with an
apologetic error message.
This is implemented for the apply command in particular because this is
the one command where new objects are created in real APIs that we don't
want to lose track of. For other operations it's less bad to just generate
a simple error message and have the user retry.
This fixes#14298.
The backend apply operation doesn't need to output the same text as the
cli itself. Instead notify the user that we are in the process of
stopping the operation.
The documentation for Refresh indicates that it will always return a
valid state, but that wasn't true in the case of a graph builder error.
While this same concept wasn't documented for Apply, it was still
assumed in the terraform apply code.
Since the helper testing framework relies on the absence of a state to
determine if it can call Destroy, the Context can't can't start
returning a state in all cases. Document this, and use the State method
to fetch the correct state value after Apply.
Add a nil check to the WriteState function, so that writing a nil state
is a noop.
Make sure to init before sorting the state, to make sure we're not
attempting to sort nil values. This isn't technically needed with the
current code, but it's just safer in general.
Add fields required to create an appropriate context for all calls to
clistate.Lock.
Add missing checks for Meta.stateLock, where we would attempt to lock,
even if locking should be skipped.
- Have the ui Lock helper use state.LockWithContext.
- Rename the message package to clistate, since that's how it's imported
everywhere.
- Use a more idiomatic placement of the Context in the LockWithContext
args.
This prevents Terraform from crashing on apply/destroy with a directory
with no Terraform configuration files. We allow a destroy with no files
but not an apply.
Have the defer'ed State.Unlock call append any error to the
RunningOperation.Err field. Local error would be rare and
self-correcting, but when the backend.Local is using a remote state the
error may require user intervention.
The local backend implementation is an implementation of
backend.Enhanced that recreates all the behavior of the CLI but through
the backend interface.
Martin Atkins