r/lb_target_group: Respect threshold & interval for TCP LBs

[radeksimko]

Something I noticed when reading #2170

Although most issues were solved in #2251 we also (IMO unintentionally) ignored UnhealthyThresholdCount and interval.

Interval cannot be updated after initial creation, so I just added appropriate error message after pondering with CustomizeDiff and realizing that it doesn't work for nested fields (yet) 😞

Closes #2170

Test results

TF_ACC=1 go test ./aws -v -run=TestAccAWSLBTargetGroup_networkLB_TargetGroup -timeout 120m
=== RUN   TestAccAWSLBTargetGroup_networkLB_TargetGroup
--- PASS: TestAccAWSLBTargetGroup_networkLB_TargetGroup (160.47s)
PASS
ok  	github.com/terraform-providers/terraform-provider-aws/aws	160.498s

[apparentlymart]

From our chat just now I learned that ResourceDiff.ForceNew doesn't accept dot-separated paths like this and that's why you are doing this check in here.

The downside of doing it in here is that it won't fail until apply time. A possible compromise is to do this check inside CustomizeDiff and have it return an error (rather than calling ForceNew) if it detects a change like this. That way it will fail during plan time rather than apply time.

Not ideal of course, but I think better than generating a plan successfully and then bailing out partway through apply.

[radeksimko]

Ha, that's a good idea actually 🤔 I'll change it.

[catsby]

Curious why we didn't use the customize diff to mark the attribute as ForceNew here and document that they can't be changed?

[radeksimko]

@catsby this is because CustomizeDiff doesn't work for nested fields (yet) - per our recent conversation on Slack.

[ghost]

I'm going to lock this issue because it has been closed for 30 days ⏳. This helps our maintainers find and focus on the active issues.

If you feel this issue should be reopened, we encourage creating a new issue linking back to this one for added context. Thanks!