example fails to run

[dan]

I installed according to the directions here and verified that I have the right versions for ubuntu (18.04), ros (melodic), and gazebo (9.6.0). The installation seemed to go OK, but when I try to run roslaunch osrf_gear sample_environment.launch I get the following errors:

Traceback (most recent call last):
  File "/opt/ros/melodic/lib/osrf_gear/gazebo_unpauser.py", line 30, in <module>
    rospy.wait_for_service('/gazebo/unpause_physics')
  File "/opt/ros/melodic/lib/python2.7/dist-packages/rospy/impl/tcpros_service.py", line 160, in wait_for_service
    rospy.core.logwarn_throttle(10, "wait_for_service(%s): failed to contact, will keep trying"%resolved_name)
  File "/opt/ros/melodic/lib/python2.7/dist-packages/rospy/core.py", line 243, in logwarn_throttle
    _base_logger(msg, logger_throttle=period, logger_level='warn')
  File "/opt/ros/melodic/lib/python2.7/dist-packages/rospy/core.py", line 184, in _base_logger
    if _logging_throttle(caller_id, throttle):
  File "/opt/ros/melodic/lib/python2.7/dist-packages/rospy/core.py", line 222, in __call__
    now = rospy.Time.now()
  File "/opt/ros/melodic/lib/python2.7/dist-packages/rospy/rostime.py", line 155, in now
    return get_rostime()
  File "/opt/ros/melodic/lib/python2.7/dist-packages/rospy/rostime.py", line 190, in get_rostime
    raise rospy.exceptions.ROSInitException("time is not initialized. Have you called init_node()?")
rospy.exceptions.ROSInitException: time is not initialized. Have you called init_node()?
[gazebo_unpauser-18] process has died [pid 10922, exit code 1, cmd /opt/ros/melodic/lib/osrf_gear/gazebo_unpauser.py __name:=gazebo_unpauser __log:=/home/dbarry/.ros/log/aff3f22e-3de5-11e9-a9ce-94de80ba34f3/gazebo_unpauser-18.log].

[dan]

I setup another machine with a new install of Ubuntu 18.04. In that case, gazebo failed to run at first, but after sudo apt upgrade libignition-math2 it worked. And then roslaunch osrf_gear sample_environment.launch works, so my older machine (one that ran ariac2) must have some residual code that causes the error.

[sumanth nirmal]

I had a similar problem with symbol lookup error when launching Gazebo using roslaunch osrf_gear sample_environment.launch, which was resolved by upgrading libignition-math2 sudo apt upgrade libignition-math2

I have also managed to make docker containerized environment for ARIAC2019 https://github.com/sumanth-nirmal/ariac2019-docker#quick-start hope that helps to start off with the initial environment setup.

[dan]

Since it works with a new build and also with docker, the issue must be machine-specific, so I'm marking it resolved. However, I would suggest that the need for an updated ignition-math2 library should be included in the wiki.

[Rud Merriam]

I just ran into the ignition problem installing on my laptop so a mention on the Wiki is a good idea.

[Shane Loretz]

@dan I added a note to the wiki about upgrading ignition math https://bitbucket.org/osrf/ariac/wiki/2019/tutorials/installation

apt show libgazebo9 says gazebo 9 depends on libignition-math4 instead of libignition-math2. Is that the exact command you ran? I'm surprised upgrading libignition-math2 fixed the issue for you.