Question about roslaunch and remote processes

edit

Hi everyone,

This is a repost of two questions formulated to ros-users@code.ros.org , to make the answers easier to find for other users. The original thread is

https://code.ros.org/lurker/message/20110725.175028.97fe0f40.en.html

Firstly, the output=screen attribute seems to be ignored, since I don't get any output with lines like:

<launch>
  <node machine="fugu-c" pkg="memsense_imu" type="imu_node"
        name="imu_node" output="screen">
    <rosparam file="$(find fugu_configurations)/imu/params.yaml" />
    <param name="frame_id" value="imu" />
  </node>
</launch>

I am sure (because I wrote it myself) that the node is using the rosconsole macros for output. According to the wiki, one of the reasons to use the macros instead of the standard c++ streams is the possibility to get output from remotely launched processes. Does anyone know what may be happening?

The machine file looks like this:

<launch>
<machine name="fugu-c" address="fugu-c.local" user="user"
    ros-root="/opt/ros/diamondback/ros/"
    ros-package-path="/home/user/ros:/opt/ros/diamondback/stacks" />
</launch>

And the second one, it seems that the roslaunch mechanism does not honour the ROS_HOSTNAME variable for remote machines. In the .bashrc file of the remote machine this variable is set to 'fugu-c.local', to allow the remote machine name to be resolved properly using Avahi (that seems to become quite standard in the latest distributions, this is the reason for the .local suffix). However when launching the above file, connection is stablished with the remote machine, even the core is found if running there, but any node is launched. This is the output:

started roslaunch server http://10.42.43.1:51495/
remote[fugu-c.local-0] starting roslaunch
remote[fugu-c.local-0]: creating ssh connection to fugu-c.local:22, user[user]
remote[fugu-c.local-0]: ssh connection created

SUMMARY
========

PARAMETERS
 ...
MACHINES
 * fugu-c

NODES
  /
    imu_node (memsense_imu/imu_node)
ROS_MASTER_URI=http://fugu-c.local:11311
core service [/rosout] found
error launching on [fugu-c.local-0, uri http://fugu-c:39451/]: Name or service not known
Launch of the following nodes most likely failed: memsense_imu/imu_node

Apparently, the uri is computed as the result of the hostname command on the remote machine, which returns only 'fugu-c' instead of 'fugu-c.local'. I expected that setting the ROS_HOSTNAME would overwrite this behaviour (actually it works for finding the remote core). If this is a bug or a possible improvement, where should I submmit it? If not, any idea on how to handle this? By now, we added the corresponding entry to /etc/hosts to overcome the problem, but I would expect a better solution.

Thank you in advance!