Config override

src/ConfigFile.java

@@ -10,18 +10,32 @@
 public class ConfigFile extends Config
 {
     private Properties props;
+    private String env_override_prefix;
 
     public ConfigFile(String file_name)
         throws java.io.IOException
     {
         props = new Properties();
 
         props.load(new FileInputStream(file_name));
+
+        if (get("env_override_prefix") != null)
+        {
+          env_override_prefix = get("env_override_prefix");
+        }
     }
 
     @Override
     public String get(String key)
     {
-        return props.getProperty(key);
+      if (env_override_prefix != null)
+      {
+        String k = env_override_prefix + key;
+        if (System.getenv().containsKey(k))
+        {
+          return System.getenv().get(k);
+        }
+      }
+      return props.getProperty(key);
     }
 }