refactor: Framework migration metal connection resource and datasource

[ocobles]

Migration of equinix_metal_connection and datasource equinix_metal_connection‡

[codecov-commenter]

Codecov Report

Attention: Patch coverage is 0% with 891 lines in your changes are missing coverage. Please review.

Project coverage is 42.08%. Comparing base (837e2c7) to head (d03eb33).

Files	Patch %	Lines
internal/resources/metal/connection/resource.go	0.00%	371 Missing ⚠️
internal/resources/metal/connection/models.go	0.00%	183 Missing ⚠️
...rnal/resources/metal/connection/resource_schema.go	0.00%	164 Missing ⚠️
...al/resources/metal/connection/datasource_schema.go	0.00%	93 Missing ⚠️
internal/resources/metal/connection/datasource.go	0.00%	45 Missing ⚠️
internal/errors/diags.go	0.00%	23 Missing ⚠️
internal/errors/must.go	0.00%	6 Missing ⚠️
internal/resources/metal/connection/speed.go	0.00%	6 Missing ⚠️

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Additional details and impacted files

@@            Coverage Diff             @@
##             main     #572      +/-   ##
==========================================
- Coverage   44.46%   42.08%   -2.39%     
==========================================
  Files          93       98       +5     
  Lines       18164    18401     +237     
==========================================
- Hits         8077     7744     -333     
- Misses       9883    10453     +570     
  Partials      204      204              

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[ctreatma]

Can't tell where exactly it's coming from, but I see a large number of test failures in CI, and I see this error message as well:

    resource_metal_device_acc_test.go:225: Step 1/1 error: Error running pre-apply plan: exit status 1
        
        Error: failed to read schema for equinix_metal_project.test in registry.terraform.io/hashicorp/equinix: failed to retrieve schema from provider "registry.terraform.io/hashicorp/equinix": Error converting data source schema: The schema for the data source "equinix_metal_connection" couldn't be converted into a usable type. This is always a problem with the provider. Please report the following to the provider developer:
        
        AttributeName("service_tokens"): protocol version 5 cannot have Attributes set

In addition to the attribute mentioned in there, I also see references to hashicorp/equinix, but I don't know if that's an issue with our code or with the way terraform prints error messages.

[ocobles]

last test execution failed in https://github.com/equinix/terraform-provider-equinix/actions/runs/7997097147/job/21840875078?pr=572#step:6:3250 but it works locally

And same with https://github.com/equinix/terraform-provider-equinix/actions/runs/7997097147/job/21840875078?pr=572#step:6:3121

--
EDIT

FIXED in last execution after main rebase

https://github.com/equinix/terraform-provider-equinix/actions/runs/8001476205/job/21852771244?pr=572#step:6:3367

https://github.com/equinix/terraform-provider-equinix/actions/runs/8001476205/job/21852771244?pr=572#step:6:3403

[ctreatma]

I can't claim to have gone through all 2000 lines of this change with a fine-toothed comb, but everything looks good to me and I see that the only test failures are for things that would not be impacted by these changes.

[displague]

Does this version number need to be bumped going forward?

[ocobles]

not necessarily, since it is the latest version available with the resource using sdkv2. In fact, we can remove this test once migrated, it helped validate compatibility

[ocobles]

Lessons Learned and Changes Introduced:

• Migrating to protocol v5, computed blocks are now implemented using a ListAttribute with an ElementType of types.ObjectType. This results in the loss of underlying field properties, meaning we no longer have descriptions of object fields. https://developer.hashicorp.com/terraform/plugin/framework/migrating/attributes-blocks/blocks-computed
• When nested schemas contain editable fields, schema.ListNestedBlock should be used instead of schema.ListNestedAttribute, as the latter is only available for protocolv6.
• Utilizing custom types enables us to obtain the ObjectType of the model using reflection.
• Fields like "facility," which are optional, computed, and have the plan modifier "RequiresReplace," should use https://developer.hashicorp.com/terraform/plugin/framework/resources/plan-modification#usestateforunknown. Otherwise, when there is an update to any other field, this field would be marked as (known after apply), thus forcing a replace.
• With the absence of StateFunc, logic must be added in Parse model. This will occur in all "metro" resources where we convert the value to lowercase. Refer to

  terraform-provider-equinix/internal/resources/metal/connection/models.go

  Lines 120 to 126 in 03ca887

  	// TODO(ocobles) we were using "StateFunc: converters.ToLowerIf" for "metro" field in the sdkv2
  	// version of this resource. StateFunc doesn't exist in terraform and it requires implementation
  	// of bespoke logic before storing state. To ensure backward compatibility we ignore lower/upper
  	// case diff for now, but we may want to require input upper case
  	if !strings.EqualFold(metro.ValueString(), conn.Metro.Code) {
  	*metro = types.StringValue(conn.Metro.Code)
  	}

  for guidance.