Add testcontainer for agent image with nginx

apps/container/src/env.rs

@@ -32,6 +32,10 @@ impl EnvFile {
         env_file
     }
 
+    pub fn write_line(&mut self, key: &str, value: &str) {
+        self._write_line_buffer(key, value);
+    }
+
     pub fn write(&mut self, stream: &mut dyn Write, with_prefix: bool) {
         self._write_buffer(stream, with_prefix);
     }