During the input walk we stash the values resulting from user input
(if any) in the eval context for use when later walks need to resolve
the provider config.
However, this repository of input results is only able to represent
literal values, since it does not retain the record of which of the keys
have values that are "computed".
Previously we were blindly stashing all of the results, failing to
consider that some of them might be computed. That resulted in the
UnknownValue placeholder being misinterpreted as a literal value when
the data is used later, which ultimately resulted in it clobbering the
actual expression evaluation result and thus causing the provider to
fail to configure itself.
Now we are careful to only retain in this repository the keys whose values
are known statically during the input phase. This eventually gets merged
with the dynamic evaluation results on subsequent walks, with the dynamic
keys left untouched due to their absence from the stored input map.
This fixes#11264.
These are required fields
```
$ terraform plan
2 error(s) occurred:
* aws_autoscaling_group.bar: "max_size": required field is not set
* aws_autoscaling_group.bar: "min_size": required field is not set
```
For our ECS service definition we have this snippet at the
`load_balancer`.
The `target_group_arn` is being pupulated by an external service that
returns the arn based on a simple string from our microservices list.
If the arn changed, this would not cause a recreation of the service and
leaving a dangling pointer to an arn that does not exist anymore.
```
load_balancer {
target_group_arn = "${lookup(var.target_group_mapping, element(values(var.microservices), count.index))}"
container_name = "${element(values(var.microservices), count.index)}"
container_port = "${var.container_port}"
}
```
The fix is adding another field to the set that's creating the ELB/ALB
definition. From looking into the git history seems this code was
created prior to ALB thus not having this field available at the time.
Service is being recreated as expected, no other services are affected
(expected behavior)
James Bardin