added "getValueByOrderedKeys" function to support more dynamic keys in

secrets

README.md

@@ -123,4 +123,18 @@ A working example can be found in `examples/k8s`. The files inside manifests dir
     $ kubectl exec apache-demo-8479b98dd4-82jnn -c apache -- cat /path/to/secret/config
    key1=valueFromSecret
    key2=2ndValueFromSecret
-    ```
+    ```
+
+## Advanced features
+### getValueByOrderedKeys
+This extension allows you to use dynamic keys in your secrets, which could happen if you use an external Secret operator for example.
+
+When is this useful? E.g. if you use keys inside Secrets to represent some kind of hierarchical configuration:
+```yaml
+value: my-value
+value_aws: aws-specific-value
+value_azure: azure-specific-value
+```
+
+Use the following line to access it: `value={{ getValueByOrderedKeys (index .Secrets "secretValues") "value_aws" "value" }}`
+This will return the value for the first matching key in `.Secrets.secretValues`, `aws-specific-value` but would fall back to `my-value` in case it does not find a value for key `value_aws`.

examples/k8s/configmap.yml

@@ -4,5 +4,5 @@ metadata:
   name: apache-demo-cfg
 data:
   secret-config: |-
-    key1={{ index .Secrets "apache-demo" "secret1" }}
+    key1={{ getValueByOrderedKeys (index .Secrets "apache-demo") "secret1" }}
     key2={{ index .Secrets "apache-demo" "secret2" }}

examples/simple/templates/etc/config

@@ -1,2 +1,2 @@
-test1={{ .Secrets.example.TEST1 }}
+test1={{ getValueByOrderedKeys (index .Secrets "example") "notExistingKey" "TEST1" }}
 test2={{ .Secrets.example.TEST2 }}

main.go

@@ -51,8 +51,11 @@ func main() {
 }
 
 func renderSecretsIntoTemplates(templatePaths []string, leftDelimiter string, rightDelimiter string, continueOnMissingKey bool, targetBasePath string, templateBasePath string, secrets map[string]map[string]string) error {
+	funcMap := template.FuncMap{
+		"getValueByOrderedKeys": getValueByOrderedKeys,
+	}
 	for _, templatePath := range templatePaths {
-		t, err := template.ParseFiles(templatePath)
+		t, err := template.New(path.Base(templatePath)).Funcs(funcMap).ParseFiles(templatePath)
 		if err != nil {
 			return fmt.Errorf("failed to parse template files(%q): %w", templatePath, err)
 		}
@@ -67,8 +70,11 @@ func renderSecretsIntoTemplates(templatePaths []string, leftDelimiter string, ri
 		if err != nil {
 			return fmt.Errorf("failed to create target dir for %q: %w", templatePath, err)
 		}
-		targetFile, _ := os.Create(targetPath)
-		err = t.Execute(targetFile, struct {
+		targetFile, err := os.Create(targetPath)
+		if err != nil {
+			return fmt.Errorf("failed to create target file at %q: %w", targetPath, err)
+		}
+		err = t.Funcs(funcMap).Execute(targetFile, struct {
 			Secrets map[string]map[string]string
 		}{
 			Secrets: secrets,
@@ -143,3 +149,13 @@ func mkDirIfNotExists(path string) error {
 
 	return nil
 }
+
+func getValueByOrderedKeys(stringMap map[string]string, keys ...string) (string, error) {
+	for _, key := range keys {
+		val, ok := stringMap[key]
+		if ok {
+			return val, nil
+		}
+	}
+	return "", fmt.Errorf("no matching key found in secret")
+}

main_test.go

@@ -127,3 +127,61 @@ func Test_getAllTemplateFilePaths(t *testing.T) {
 		t.Errorf("getAllTemplateFilePaths() = %v, want %v", tempPaths, wantedResult)
 	}
 }
+
+func Test_getValueByOrderedKeys(t *testing.T) {
+	tests := []struct {
+		name      string
+		stringMap map[string]string
+		keys      []string
+		want      string
+		wantErr   bool
+	}{
+		{
+			name:      "one-match",
+			stringMap: map[string]string{"key1": "val1"},
+			keys:      []string{"key1"},
+			want:      "val1",
+			wantErr:   false,
+		},
+		{
+			name:      "match-first",
+			stringMap: map[string]string{"key1": "val1", "key2": "val2"},
+			keys:      []string{"key1"},
+			want:      "val1",
+			wantErr:   false,
+		},
+		{
+			name:      "match-second",
+			stringMap: map[string]string{"key1": "val1", "key2": "val2"},
+			keys:      []string{"key2"},
+			want:      "val2",
+			wantErr:   false,
+		},
+		{
+			name:      "skip-first-match-second",
+			stringMap: map[string]string{"key1": "val1", "key2": "val2"},
+			keys:      []string{"key3", "key2"},
+			want:      "val2",
+			wantErr:   false,
+		},
+		{
+			name:      "key-not-found",
+			stringMap: map[string]string{"key1": "val1", "key2": "val2"},
+			keys:      []string{"key3"},
+			want:      "",
+			wantErr:   true,
+		},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			got, err := getValueByOrderedKeys(tt.stringMap, tt.keys...)
+			if (err != nil) != tt.wantErr {
+				t.Errorf("getValueByOrderedKeys() error = %v, wantErr %v", err, tt.wantErr)
+				return
+			}
+			if got != tt.want {
+				t.Errorf("getValueByOrderedKeys() got = %v, want %v", got, tt.want)
+			}
+		})
+	}
+}