Incorporate the review comment from Julien

Signed-off-by: ChenYing Kuo <[email protected]>

README.md

@@ -150,7 +150,7 @@ A typical usage is to run 1 bridge in a robot, and 1 bridge in another host moni
 It's important to make sure that NO DDS communication can occur between 2 hosts that are bridged by `zenoh-bridge-ros2dds`. Otherwise, some duplicate or looping traffic can occur.  
 To make sure of this, you can either:
 
-- define `ROS_LOCALHOST_ONLY=1`.  
+- use ROS_AUTOMATIC_DISCOVERY_RANGE=LOCALHOST after Iron and ROS_LOCALHOST_ONLY=1 before Iron.  
   Preferably, enable MULTICAST on the loopback interface with this command (on Linux): `sudo ip l set lo multicast on`
 - use different `ROS_DOMAIN_ID` on each hosts
 - use a `CYCLONEDDS_URI` that configures CycloneDDS to only use internal interfaces to the robot. This configuration has to be used for all ROS Nodes as well as for the bridge.  

zenoh-plugin-ros2dds/src/config.rs

@@ -501,15 +501,15 @@ where
     D: Deserializer<'de>,
 {
     let discovery_range: String = Deserialize::deserialize(deserializer).unwrap();
-    Ok(Some(match discovery_range.as_str() {
-        "SUBNET" => RosAutomaticDiscoveryRange::Subnet,
-        "LOCALHOST" => RosAutomaticDiscoveryRange::Localhost,
-        "OFF" => RosAutomaticDiscoveryRange::Off,
-        "SYSTEM_DEFAULT" => RosAutomaticDiscoveryRange::SystemDefault,
-        unknown => {
-            panic!(r#"Invalid parameter {unknown} for ROS_AUTOMATICALLY_DISCOVERY_RANGE"#)
-        }
-    }))
+    match discovery_range.as_str() {
+        "SUBNET" => Ok(Some(RosAutomaticDiscoveryRange::Subnet)),
+        "LOCALHOST" => Ok(Some(RosAutomaticDiscoveryRange::Localhost)),
+        "OFF" => Ok(Some(RosAutomaticDiscoveryRange::Off)),
+        "SYSTEM_DEFAULT" => Ok(Some(RosAutomaticDiscoveryRange::SystemDefault)),
+        unknown => Err(de::Error::custom(format!(
+            r#"Invalid parameter {unknown} for ROS_AUTOMATICALLY_DISCOVERY_RANGE"#
+        ))),
+    }
 }
 
 fn deserialize_static_peers<'de, D>(deserializer: D) -> Result<Option<Vec<String>>, D::Error>
@@ -528,7 +528,6 @@ where
     } else {
         Ok(Some(peer_list))
     }
-    //deserializer.deserialize_option(OptPathVisitor)
 }
 
 fn default_transient_local_cache_multiplier() -> usize {

zenoh-plugin-ros2dds/src/lib.rs

@@ -303,6 +303,14 @@ pub async fn run(runtime: Runtime, config: Config) {
     // Dynamic Discovery is changed after iron. Need to check the ROS 2 version.
     // https://docs.ros.org/en/rolling/Tutorials/Advanced/Improved-Dynamic-Discovery.html
     if ros_distro_is_less_than("iron") {
+        if config.ros_automatic_discovery_range.is_some() {
+            tracing::warn!("ROS_AUTOMATIC_DISCOVERY_RANGE will be ignored since it's not supported before ROS 2 Iron");
+        }
+        if config.ros_static_peers.is_some() {
+            tracing::warn!(
+                "ROS_STATIC_PEERS will be ignored since it's not supported before ROS 2 Iron"
+            );
+        }
         // if "ros_localhost_only" is set, configure CycloneDDS to use only localhost interface
         if config.ros_localhost_only {
             env::set_var(
@@ -318,6 +326,8 @@ pub async fn run(runtime: Runtime, config: Config) {
         let (ros_automatic_discovery_range, ros_static_peers) = if config.ros_localhost_only {
             // If ROS_LOCALHOST_ONLY is set, need to transform into new environmental variables
             // Refer to https://github.com/ros2/ros2_documentation/pull/3519#discussion_r1186541935
+            tracing::warn!("ROS_LOCALHOST_ONLY is deprecated but still honored if it is enabled. Use ROS_AUTOMATIC_DISCOVERY_RANGE and ROS_STATIC_PEERS instead.");
+            tracing::warn!("'localhost_only' is enabled, 'automatic_discovery_range' and 'static_peers' will be ignored.");
             (Some(RosAutomaticDiscoveryRange::Localhost), None)
         } else {
             (