Add poll_function

This adds a poll_function argument that can be used to configure the function used
during the polling (default: exponential).

hcloud/plugin_provider.go

@@ -56,6 +56,10 @@ func (p *PluginProvider) Schema(_ context.Context, _ provider.SchemaRequest, res
 				Description: "The interval at which actions are polled by the client. Default `500ms`. Increase this interval if you run into rate limiting errors.",
 				Optional:    true,
 			},
+			"poll_function": schema.StringAttribute{
+				Description: "The type of function to be used during the polling.",
+				Optional:    true,
+			},
 		},
 		// TODO: Uncomment once we get rid of the SDK v2 Provider
 		// MarkdownDescription: `The Hetzner Cloud (hcloud) provider is used to interact with the resources supported by
@@ -69,6 +73,7 @@ type PluginProviderModel struct {
 	Token        types.String `tfsdk:"token"`
 	Endpoint     types.String `tfsdk:"endpoint"`
 	PollInterval types.String `tfsdk:"poll_interval"`
+	PollFunction types.String `tfsdk:"poll_function"`
 }
 
 // Configure is called at the beginning of the provider lifecycle, when
@@ -121,7 +126,6 @@ func (p *PluginProvider) Configure(ctx context.Context, req provider.ConfigureRe
 				fmt.Sprintf("An unexpected error was encountered trying to parse the value.\n\n%s", err.Error()),
 			)
 		}
-		opts = append(opts, hcloud.WithPollBackoffFunc(hcloud.ExponentialBackoff(2, pollInterval)))
 	}
 
 	if resp.Diagnostics.HasError() {

hcloud/provider.go

@@ -68,6 +68,13 @@ func Provider() *schema.Provider {
 				Default:     "500ms",
 				Description: "The interval at which actions are polled by the client. Default `500ms`. Increase this interval if you run into rate limiting errors.",
 			},
+			"poll_function": {
+				Type:        schema.TypeString,
+				Optional:    true,
+				Default:     "exponential",
+				Description: "The type of function to be used during the polling.",
+				ExactlyOneOf: []string{"constant", "exponential"},
+			},
 		},
 		ResourcesMap: map[string]*schema.Resource{
 			certificate.UploadedResourceType:  certificate.UploadedResource(),
@@ -139,7 +146,12 @@ func providerConfigure(_ context.Context, d *schema.ResourceData) (interface{},
 		if err != nil {
 			return nil, hcclient.ErrorToDiag(err)
 		}
-		opts = append(opts, hcloud.WithPollBackoffFunc(hcloud.ConstantBackoff(pollInterval)))
+		pollFunction, ok := d.GetOk("poll_function")
+		if ok && pollFunction == "constant" {
+			opts = append(opts, hcloud.WithPollBackoffFunc(hcloud.ConstantBackoff(pollInterval)))
+		} else {
+			opts = append(opts, hcloud.WithPollBackoffFunc(hcloud.ExponentialBackoff(2, pollInterval)))
+		}
 	}
 	if logging.LogLevel() != "" {
 		opts = append(opts, hcloud.WithDebugWriter(log.Writer()))