Adding Resource Name Generation Support

Terraform AWS Provider resources can use shared logic to support and test name generation, where the operator can choose between an expected naming value, a generated naming value with a prefix, or a fully generated name.

Implementing name generation requires modifying the following:

• Resource Code: In the resource code, add a name_prefix attribute, along with handling in the Create function.
• Resource Acceptance Tests: In the resource acceptance tests, add new acceptance test functions and configurations to exercise the naming logic.
• Resource Documentation: In the resource documentation, add the name_prefix argument and update the name argument description.

Resource Code

• In the resource file (e.g., internal/service/{service}/{thing}.go), add the following import: "github.com/hashicorp/terraform-provider-aws/internal/create".
• Inside the resource schema, add the new name_prefix attribute and adjust the name attribute to be Optional, Computed, and conflict with the name_prefix attribute. Be sure to keep any existing validation functions already present on the name.

Terraform Plugin Framework (Preferred)Terraform Plugin SDK V2

"name": schema.StringAttribute{
    Optional: true
    Computed: true,
    PlanModifiers: []planmodifier.String{
        stringplanmodifier.UseStateForUnknown(),
        stringplanmodifier.RequiresReplace(),
    },
    Validators: append(
        stringvalidator.ExactlyOneOf(
            path.MatchRelative().AtParent().AtName("name"),
            path.MatchRelative().AtParent().AtName("name_prefix"),
        ),
    ),
},
"name_prefix": schema.StringAttribute{
    Optional:   true,
    Computed:   true,
    PlanModifiers: []planmodifier.String{
        stringplanmodifier.UseStateForUnknown(),
        stringplanmodifier.RequiresReplace(),
    },
},

"name": {
  Type:          schema.TypeString,
  Optional:      true,
  Computed:      true,
  ForceNew:      true,
  ConflictsWith: []string{"name_prefix"},
},
"name_prefix": {
  Type:          schema.TypeString,
  Optional:      true,
  Computed:      true,
  ForceNew:      true,
  ConflictsWith: []string{"name"},
},

• In the resource Create function, make use of the create.Name() function.

Terraform Plugin Framework (Preferred)Terraform Plugin SDK V2

name := create.Name(plan.Name.ValueString(), plan.NamePrefix.ValueString())

// ... in AWS Go SDK V2 Input types, etc. use aws.ToString(name)

name := create.Name(d.Get("name").(string), d.Get("name_prefix").(string))

// ... in AWS Go SDK V2 Input types, etc. use aws.ToString(name)

• If the resource supports import, set both name and name_prefix in the resource Read function.

Terraform Plugin Framework (Preferred)Terraform Plugin SDK V2

state.Name = flex.StringToFramework(ctx, resp.Name)
state.NamePrefix = create.NamePrefixFromName(flex.StringToFramework(ctx, resp.Name))

d.Set("name", resp.Name)
d.Set("name_prefix", create.NamePrefixFromName(aws.StringValue(resp.Name)))

Resource Acceptance Tests

• In the resource test file (e.g., internal/service/{service}/{thing}_test.go), add the following import: "github.com/hashicorp/terraform-provider-aws/internal/create".
• Implement two new tests named _nameGenerated and _namePrefix which verify the creation of the resource without name and name_prefix arguments, and with only the name_prefix argument, respectively.

func TestAccServiceThing_nameGenerated(t *testing.T) {
  ctx := acctest.Context(t)
  var thing service.ServiceThing
  resourceName := "aws_service_thing.test"

  resource.ParallelTest(t, resource.TestCase{
    PreCheck:                 func() { acctest.PreCheck(ctx, t) },
    ErrorCheck:               acctest.ErrorCheck(t, names.ServiceServiceID),
    ProtoV5ProviderFactories: acctest.ProtoV5ProviderFactories,
    CheckDestroy:             testAccCheckThingDestroy(ctx),
    Steps: []resource.TestStep{
      {
        Config: testAccThingConfig_nameGenerated(),
        Check: resource.ComposeTestCheckFunc(
          testAccCheckThingExists(ctx, resourceName, &thing),
          acctest.CheckResourceAttrNameGenerated(resourceName, "name"),
          resource.TestCheckResourceAttr(resourceName, "name_prefix", id.UniqueIdPrefix),
        ),
      },
      // If the resource supports import:
      {
        ResourceName:      resourceName,
        ImportState:       true,
        ImportStateVerify: true,
      },
    },
  })
}

func TestAccServiceThing_namePrefix(t *testing.T) {
  ctx := acctest.Context(t)
  var thing service.ServiceThing
  resourceName := "aws_service_thing.test"

  resource.ParallelTest(t, resource.TestCase{
    PreCheck:                 func() { acctest.PreCheck(ctx, t) },
    ErrorCheck:               acctest.ErrorCheck(t, names.ServiceServiceID),
    ProtoV5ProviderFactories: acctest.ProtoV5ProviderFactories,
    CheckDestroy:             testAccCheckThingDestroy(ctx),
    Steps: []resource.TestStep{
      {
        Config: testAccThingConfig_namePrefix("tf-acc-test-prefix-"),
        Check: resource.ComposeTestCheckFunc(
          testAccCheckThingExists(ctx, resourceName, &thing),
          acctest.CheckResourceAttrNameFromPrefix(resourceName, "name", "tf-acc-test-prefix-"),
          resource.TestCheckResourceAttr(resourceName, "name_prefix", "tf-acc-test-prefix-"),
        ),
      },
      // If the resource supports import:
      {
        ResourceName:      resourceName,
        ImportState:       true,
        ImportStateVerify: true,
      },
    },
  })
}

func testAccThingConfig_nameGenerated() string {
  return fmt.Sprintf(`
resource "aws_service_thing" "test" {
  # ... other configuration ...
}
`)
}

func testAccThingConfig_namePrefix(namePrefix string) string {
  return fmt.Sprintf(`
resource "aws_service_thing" "test" {
  # ... other configuration ...

  name_prefix = %[1]q
}
`, namePrefix)
}

Resource Documentation

• In the resource documentation (e.g., website/docs/r/{service}_{thing}.html.markdown), add the following to the arguments reference.

* `name_prefix` - (Optional) Creates a unique name beginning with the specified prefix. Conflicts with `name`.

• Adjust the existing name argument description to ensure it is denoted as Optional, mention that it can be generated and that it conflicts with name_prefix.

* `name` - (Optional) Name of the thing. If omitted, Terraform will assign a random, unique name. Conflicts with `name_prefix`.