Fix hostname config decoding for read-only data sources

internal/provider/config_hostname.go

@@ -0,0 +1,41 @@
+package provider
+
+import (
+	"fmt"
+
+	"github.com/hashicorp/terraform-plugin-framework/types"
+	"github.com/hashicorp/terraform-plugin-framework/tfsdk"
+	"github.com/hashicorp/terraform-plugin-go/tftypes"
+)
+
+func hostnameFromConfig(config tfsdk.Config) (types.String, error) {
+	if !config.Raw.IsKnown() {
+		return types.StringUnknown(), nil
+	}
+	if config.Raw.IsNull() {
+		return types.StringNull(), nil
+	}
+
+	attributes := map[string]tftypes.Value{}
+	if err := config.Raw.As(&attributes); err != nil {
+		return types.StringNull(), fmt.Errorf("decode data source config object: %w", err)
+	}
+
+	hostnameValue, ok := attributes["hostname"]
+	if !ok {
+		return types.StringNull(), fmt.Errorf("hostname is missing from data source config")
+	}
+	if !hostnameValue.IsKnown() {
+		return types.StringUnknown(), nil
+	}
+	if hostnameValue.IsNull() {
+		return types.StringNull(), nil
+	}
+
+	var hostname string
+	if err := hostnameValue.As(&hostname); err != nil {
+		return types.StringNull(), fmt.Errorf("decode hostname: %w", err)
+	}
+
+	return types.StringValue(hostname), nil
+}