Don't panic when the template is not defined (#598)

* Don't panic when the template is not defined

* Add acceptance tests

* Changelog

Author: tobio

CHANGELOG.md

@@ -1,5 +1,9 @@
 ## [Unreleased]
 
+### Fixed
+
+- Prevent a provider panic when an `elasticstack_elasticsearch_template` or `elasticstack_elasticsearch_component_template` includes an empty `template` (`template {}`) block. ([#598](https://github.com/elastic/terraform-provider-elasticstack/pull/598))
+
 ## [0.11.2] - 2024-03-13
 
 ### Fixed

internal/elasticsearch/index/component_template.go

@@ -156,62 +156,14 @@ func resourceComponentTemplatePut(ctx context.Context, d *schema.ResourceData, m
 	}
 
 	if v, ok := d.GetOk("template"); ok {
-		// only one template block allowed to be declared
-		definedTempl := v.([]interface{})[0].(map[string]interface{})
-		definedAliases := definedTempl["alias"].(*schema.Set)
-		templ := models.Template{}
-
-		aliases := make(map[string]models.IndexAlias, definedAliases.Len())
-		for _, a := range definedAliases.List() {
-			alias := a.(map[string]interface{})
-			templAlias := models.IndexAlias{}
-
-			if f, ok := alias["filter"]; ok {
-				if f.(string) != "" {
-					filterMap := make(map[string]interface{})
-					if err := json.Unmarshal([]byte(f.(string)), &filterMap); err != nil {
-						return diag.FromErr(err)
-					}
-					templAlias.Filter = filterMap
-				}
-			}
-			if ir, ok := alias["index_routing"]; ok {
-				templAlias.IndexRouting = ir.(string)
-			}
-			templAlias.IsHidden = alias["is_hidden"].(bool)
-			templAlias.IsWriteIndex = alias["is_write_index"].(bool)
-			if r, ok := alias["routing"]; ok {
-				templAlias.Routing = r.(string)
-			}
-			if sr, ok := alias["search_routing"]; ok {
-				templAlias.SearchRouting = sr.(string)
-			}
-
-			aliases[alias["name"].(string)] = templAlias
-		}
-		templ.Aliases = aliases
-
-		if mappings, ok := definedTempl["mappings"]; ok {
-			if mappings.(string) != "" {
-				maps := make(map[string]interface{})
-				if err := json.Unmarshal([]byte(mappings.(string)), &maps); err != nil {
-					return diag.FromErr(err)
-				}
-				templ.Mappings = maps
-			}
+		templ, ok, diags := expandTemplate(v)
+		if diags != nil {
+			return diags
 		}
 
-		if settings, ok := definedTempl["settings"]; ok {
-			if settings.(string) != "" {
-				sets := make(map[string]interface{})
-				if err := json.Unmarshal([]byte(settings.(string)), &sets); err != nil {
-					return diag.FromErr(err)
-				}
-				templ.Settings = sets
-			}
+		if ok {
+			componentTemplate.Template = &templ
 		}
-
-		componentTemplate.Template = &templ
 	}
 
 	if v, ok := d.GetOk("version"); ok {

internal/elasticsearch/index/template.go

@@ -257,37 +257,14 @@ func resourceIndexTemplatePut(ctx context.Context, d *schema.ResourceData, meta
 	}
 
 	if v, ok := d.GetOk("template"); ok {
-		templ := models.Template{}
-		// only one template block allowed to be declared
-		definedTempl := v.([]interface{})[0].(map[string]interface{})
-
-		aliases, diags := ExpandIndexAliases(definedTempl["alias"].(*schema.Set))
-		if diags.HasError() {
+		templ, ok, diags := expandTemplate(v)
+		if diags != nil {
 			return diags
 		}
-		templ.Aliases = aliases
-
-		if mappings, ok := definedTempl["mappings"]; ok {
-			if mappings.(string) != "" {
-				maps := make(map[string]interface{})
-				if err := json.Unmarshal([]byte(mappings.(string)), &maps); err != nil {
-					return diag.FromErr(err)
-				}
-				templ.Mappings = maps
-			}
-		}
 
-		if settings, ok := definedTempl["settings"]; ok {
-			if settings.(string) != "" {
-				sets := make(map[string]interface{})
-				if err := json.Unmarshal([]byte(settings.(string)), &sets); err != nil {
-					return diag.FromErr(err)
-				}
-				templ.Settings = sets
-			}
+		if ok {
+			indexTemplate.Template = &templ
 		}
-
-		indexTemplate.Template = &templ
 	}
 
 	if v, ok := d.GetOk("version"); ok {
@@ -303,6 +280,43 @@ func resourceIndexTemplatePut(ctx context.Context, d *schema.ResourceData, meta
 	return resourceIndexTemplateRead(ctx, d, meta)
 }
 
+func expandTemplate(config interface{}) (models.Template, bool, diag.Diagnostics) {
+	templ := models.Template{}
+	// only one template block allowed to be declared
+	definedTempl, ok := config.([]interface{})[0].(map[string]interface{})
+	if !ok {
+		return templ, false, nil
+	}
+
+	aliases, diags := ExpandIndexAliases(definedTempl["alias"].(*schema.Set))
+	if diags.HasError() {
+		return templ, false, diags
+	}
+	templ.Aliases = aliases
+
+	if mappings, ok := definedTempl["mappings"]; ok {
+		if mappings.(string) != "" {
+			maps := make(map[string]interface{})
+			if err := json.Unmarshal([]byte(mappings.(string)), &maps); err != nil {
+				return templ, false, diag.FromErr(err)
+			}
+			templ.Mappings = maps
+		}
+	}
+
+	if settings, ok := definedTempl["settings"]; ok {
+		if settings.(string) != "" {
+			sets := make(map[string]interface{})
+			if err := json.Unmarshal([]byte(settings.(string)), &sets); err != nil {
+				return templ, false, diag.FromErr(err)
+			}
+			templ.Settings = sets
+		}
+	}
+
+	return templ, true, nil
+}
+
 func resourceIndexTemplateRead(ctx context.Context, d *schema.ResourceData, meta interface{}) diag.Diagnostics {
 	client, diags := clients.NewApiClientFromSDKResource(d, meta)
 	if diags.HasError() {

internal/elasticsearch/index/template_test.go

@@ -111,6 +111,8 @@ resource "elasticstack_elasticsearch_index_template" "test2" {
   data_stream {
     hidden = false
   }
+
+  template {}
 }
 	`, name, name, name)
 }