try load ./rusty-pipe.yaml if no $CONFIG_PATH

src/config.rs

@@ -76,11 +76,13 @@ pub struct UDP {
 }
 
 pub fn build_config() -> Result<Config, String> {
-   let config_path = env::var("CONFIG_PATH");
-   match config_path {
+   match env::var("CONFIG_PATH") {
       Ok(p) => return build_config_yaml(p),
-      Err(_) => return Ok(build_config_std()),
-   }
+      Err(_) => match build_config_yaml(String::from("./rusty-pipe.yaml")) {
+         Ok(v) => return Ok(v),
+         Err(_) => return Ok(build_config_std()),
+      },
+   };
 }
 
 fn build_config_yaml(path: String) -> Result<Config, String> {

src/testdata/config-stdin-to-stdout.yaml

@@ -4,6 +4,7 @@ streams:
     engine:
       name: stdin
   output:
+    format: 'rusty-pipe.yaml: {{ VALUE }}'
     debug: true
     engine:
       name: stdout