[Discourse.ros.org] [OpenEmbedded] Meta-ros Kinetic runtime issue with roscore

[Mike Thompson]

mpthompson March 1

Hey everyone, I'm adding ros-meta to a Yocto/OpenEmbedded build of a Linux distribution for a custom Xilinx Zynq based camera board and it looks like I'm running into some runtime dependency issues when running roscore. I'm using the experimental kinetic distribution of ros-meta at: https://github.com/bulwahn/meta-ros/tree/kinetic-experimental My bblayers.conf file looks as follows: BBLAYERS ?= " \ ${TOPDIR}/../poky/meta \ ${TOPDIR}/../poky/meta-poky \ ${TOPDIR}/../poky/meta-yocto-bsp \ ${TOPDIR}/../meta-openembedded/meta-oe \ ${TOPDIR}/../meta-openembedded/meta-python \ ${TOPDIR}/../meta-openembedded/meta-multimedia \ ${TOPDIR}/../meta-xilinx \ ${TOPDIR}/../meta-ros \ ${TOPDIR}/../meta-shadowbox \ " Added the following line to by core-image.bb file: IMAGE_INSTALL += "roslaunch" Used the following command to create my own image. bitbake core-image Build completed without any errors. Created an SD card including the kernel and file system that includes ROS. On the booted Xilinx Zynq based system running the Linux environment I just built, I'm configuring ROS Kinetic with the following: export ROS_ROOT=/opt/ros/kinetic export ROS_DISTRO=kinetic export ROS_PACKAGE_PATH=/opt/ros/kinetic/share export PATH=$PATH:/opt/ros/kinetic/bin export LD_LIBRARY_PATH=/opt/ros/kinetic/lib export PYTHONPATH=/opt/ros/kinetic/lib/python2.7/site-packages export ROS_MASTER_URI=http://localhost:11311 export CMAKE_PREFIX_PATH=/opt/ros/kinetic touch /opt/ros/kinetic/.catkin I have the following problems running roscore. root@microzed-camera:~# roscore Traceback (most recent call last): File "/opt/ros/kinetic/bin/roscore", line 36, in <module> from rosmaster.master_api import NUM_WORKERS File "/opt/ros/kinetic/lib/python2.7/site-packages/rosmaster/__init__.py", line 35, in <module> from .main import rosmaster_main File "/opt/ros/kinetic/lib/python2.7/site-packages/rosmaster/main.py", line 43, in <module> import rosmaster.master File "/opt/ros/kinetic/lib/python2.7/site-packages/rosmaster/master.py", line 47, in <module> import rosmaster.master_api File "/opt/ros/kinetic/lib/python2.7/site-packages/rosmaster/master_api.py", line 72, in <module> from rosmaster.util import xmlrpcapi File "/opt/ros/kinetic/lib/python2.7/site-packages/rosmaster/util.py", line 48, in <module> from defusedxml.xmlrpc import monkey_patch ImportError: No module named defusedxml.xmlrpc root@microzed-camera:~# From what I can find on ROS Answers, it looks like defusedxml was as a fairly recent dependency added to ROS Kinetic. I assume this dependency probably didn't make it into the meta-ros dependencies. Any suggestions on how I go about adding it to the Yocto/OpenEmbedded build of the system? Thanks, Mike

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[Rohan Agrawal]

rohbotics March 2

Hey Mike, Nice to hear that the "custom Xilinx Zynq based board" is still going Defusedxml is a python package that was added to facilitate adding security to ROS, as it provides protection against a bunch of different XML attacks. This is part of the SROS effort to add some security and hardening to ROS. Anyway to get roscore to run, have you tried adding python-defusedxml as a dependency here: https://github.com/bulwahn/meta-ros/blob/kinetic-experimental/recipes-ros/ros-comm/roslaunch_1.12.2.bb#L18 I have only done some looking around at OpenEmbeded stuff, and never got around to actually using it so I am not sure if this is the 'right' way to fix this, or if it would even work. Out of curiosity what is the size of the image that comes out the build process? I would think it would quite small relative to a Ubuntu image. Rohan

[Mike Thompson]

mpthompson March 2

Hey Rohan, I resolved this issue by adding the following recipe for defusedxml to: meta-ros/recipes-devtools/python/python-defusedxml_0.4.1.bb The contents of the recipe is: DESCRIPTION = "XML bomb protection for Python stdlib modules" SECTION = "devel/python" LICENSE = "PSFL" LIC_FILES_CHKSUM = "file://PKG-INFO;beginline=8;endline=8;md5=a560e172e996ab553d352ccff41c7d20" SRCNAME = "defusedxml" SRC_URI = "http://pypi.python.org/packages/source/d/defusedxml/defusedxml-${PV}.tar.gz" SRC_URI[md5sum] = "230a5eff64f878b392478e30376d673a" SRC_URI[sha256sum] = "cd551d5a518b745407635bb85116eb813818ecaf182e773c35b36239fc3f2478" S = "${WORKDIR}/${SRCNAME}-${PV}" inherit setuptools Then adding a dependency to roslaunch_1.12.2.bb for this python module. The following commit is a complete fix. github.com/shadowboxtech/meta-ros Added python-defusedxml recipe to fix runtime dependency. by mpthompson on 05:53AM - 02 Mar 17 changed 3 files with 63 additions and 0 deletions. The resulting image file for the entire Linux OS including roscore is about 47MB in size which is considerably smaller than an Ubuntu image. However, this is for the absolute minimum user tools and ROS install. Mike

[Qnetjoe]

qnetjoe April 27

Hi Mike, I am interested in doing something similar using a Microzed, but honestly don't know where to even start, can you point me to some good resources, so I might be able to do the same? Thanks!

[Lukas Bulwahn]

bulwahn May 8

Hi Qnetjoe, I would propose that you start as follows: Get an understanding of yocto and bitbake following the Yocto Quick Start: http://www.yoctoproject.org/docs/2.2.1/yocto-project-qs/yocto-project-qs.html After stepping through that document, you should be able to build and start a small Linux image in the qemu emulator. Build and run an image with ROS for the qemu emulator following the instructions at: http://wiki.ros.org/hydro/Installation/OpenEmbedded Build and run a minimal image for the Microzed board, using the microzed configuration provided in the meta-xilinx layer at: http://git.yoctoproject.org/cgit/cgit.cgi/meta-xilinx/tree/conf/machine/microzed-zynq7.conf?h=master http://git.yoctoproject.org/cgit/cgit.cgi/meta-xilinx/tree/ By the way, I found this by searching on https://layers.openembedded.org/, and it quickly linked me to: https://layers.openembedded.org/layerindex/branch/master/machines/?q=Microzed Combine what you learned in Step 2 and Step 3, and build an image with ROS for the Microzed board. When combining, you will probably need to choose the build configuration that is a compromise between the build configurations you used in step 2 and in step 3. This will then probably need certain adjustments in meta-ros. Here some further advice: Get a build machine with a lot of CPU power, RAM and a SSD disk to build images much quicker. You will not get away with some laptop and some Linux virtual machine. when bitbaking the images. Report issues you encounter on the meta-ros github issue tracker. Please always provide at least the build configuration you use, and possibly even the bblayers.conf file, so that others can reproduce the reported issue. I hope this helps. Lukas