feat: update aws provider template (#345)

add gotemplate function to handle HCL Expression

update aws provider template to use toHCLExpression function

templates/templates/common/aws_provider.tmpl

@@ -11,30 +11,18 @@ provider "aws" {
   allowed_account_ids = ["{{ .AccountID }}"]
   {{- if and .IgnoreTags (and .IgnoreTags.Enabled (deRefBool .IgnoreTags.Enabled)) }}
   ignore_tags {
-    {{ if and .IgnoreTags.Keys (not (eq (len .IgnoreTags.Keys) 0)) }} keys = [
-    {{- range $k := .IgnoreTags.Keys }}
-      "{{ $k }}",
+    {{- if and .IgnoreTags.Keys (not (eq (len .IgnoreTags.Keys) 0)) }}
+    keys= {{ toHCLExpression .IgnoreTags.Keys }}
     {{- end }}
-    ]
-    {{- end }}
-    {{ if and .IgnoreTags.KeyPrefixes (not (eq (len .IgnoreTags.KeyPrefixes) 0)) }} key_prefixes = [
-    {{- range $k := .IgnoreTags.KeyPrefixes }}
-      "{{ $k }}",
-    {{- end }}
-    ]
+    {{- if and .IgnoreTags.KeyPrefixes (not (eq (len .IgnoreTags.KeyPrefixes) 0)) }}
+    key_prefixes = {{ toHCLExpression .IgnoreTags.KeyPrefixes }}
     {{- end }}
   }
   {{- end }}
   {{- if and .DefaultTags (and .DefaultTags.Enabled (deRefBool .DefaultTags.Enabled)) }}
   default_tags {
     {{- if .DefaultTags.Tags }}
-    tags = merge(var.tags,{
-    {{- range $k, $v := .DefaultTags.Tags }}
-      {{- if $v }}
-      {{ $k }} = "{{ $v }}"
-      {{- end }}
-    {{- end }}
-    })
+    tags = merge(var.tags, {{ toHCLExpression .DefaultTags.Tags }})
     {{- else }}
     tags = var.tags
     {{- end }}

testdata/v2_aws_default_tags/fogg.yml

@@ -82,9 +82,10 @@ envs:
           aws:
             default_tags:
               tags:
-                Component: Vox
+                "Component": Vox
                 # tags are merged and overwrite
-                Project: Overwrite
+                "Project": Overwrite
+                "hsh:team": "TIES"
         modules:
           - source: "terraform/modules/my_module"
   fred:

util/template.go

@@ -135,6 +135,39 @@ func toHCLAssignment(name string, value any) string {
 	return string(f.Bytes())
 }
 
+// toHCLExpression converts a Go value to its HCL representation as a string.
+// It can be used within templates to include the value in expressions or function calls.
+//
+// tags = merge(var.tags, {{ toHCLExpression .DefaultTags.Tags }})
+//
+//	tags = merge(var.tags, {
+//	  Component  = "Vox"
+//	  Env        = "Foo"
+//	})
+//
+// This is designed to be called from a template.
+func toHCLExpression(value any) string {
+	f := hclwrite.NewEmptyFile()
+	rootBody := f.Body()
+
+	// Since we don't have the cty type information for the value and since it can be arbitrary, we use
+	// JSON as an intermediate representation.
+	jsonBytes, err := json.Marshal(value)
+	if err != nil {
+		// Swallow errors inside of a template.
+		return ""
+	}
+	var ctyVal ctyjson.SimpleJSONValue
+	if err := ctyVal.UnmarshalJSON(jsonBytes); err != nil {
+		// Swallow errors inside of a template.
+		return ""
+	}
+
+	tokens := hclwrite.TokensForValue(ctyVal.Value)
+	rootBody.AppendUnstructuredTokens(tokens)
+	return strings.TrimSpace(string(f.Bytes()))
+}
+
 // deRef is a generic function to dereference a pointer to it's actual value type.
 //
 // This is designed to be called from a template.
@@ -153,6 +186,7 @@ func OpenTemplate(label string, source io.Reader, templates fs.FS) (*template.Te
 	funcs["deRefBool"] = deRef[bool]
 	funcs["toHclBlock"] = toHCLBlock
 	funcs["toHclAssignment"] = toHCLAssignment
+	funcs["toHCLExpression"] = toHCLExpression
 
 	s, err := io.ReadAll(source)
 	if err != nil {