Warn on startup if no mirrors are allowed

Author: cgzones

apt-cacher-rs.conf

@@ -49,8 +49,9 @@
 #aliases = []
 
 # List of allowed mirrors.
+# Note that by default no mirrors are allowed.
 # Example:
-#   allowed_mirrors = [ 'deb.debian.org' ]
+#   allowed_mirrors = [ 'deb.debian.org', '*.ubuntu.com' ]
 #allowed_mirrors = []
 
 # List of allowed clients.

src/main.rs

@@ -3053,6 +3053,10 @@ fn main() -> Result<(), Box<dyn std::error::Error + Send + Sync>> {
         }
     }
 
+    if global_config().allowed_mirrors.is_empty() {
+        warn!("No mirror allowed, consider setting option 'allowed_mirrors'");
+    }
+
     info!(
         "Using cache directory `{}`",
         global_config().cache_directory.display()