彻底解决 sudo rosdep init 和 rosdep update失败问题

如果sudo rosdep init 和 rosdep update没有执行成功，有些ROS功能会无法执行，比如rqt_tf_tree会报错：

1 2	the rosdep view is empty: call 'sudo rosdep init' and 'rosdep update' [WARN] wait_for_service(/rqt_gui_py_node_26204/tf2_frames): failed to contact, will keep trying

这两个老大难其实都是网络的问题，sudo rosdep init的目的是为了在/etc目录下新建/ros/rosdep/sources.list.d/20-default.list文件。

小鱼基于rosdep源码制作了rosdepc，专门服务国内ROS用户，使用pip3 和 rosdepc 可以彻底消灭这个问题

sudo apt-get install python3-pip 
sudo pip3 install rosdepc

sudo rosdepc init
rosdepc update

rosdep update根据20-default.list文件中的网址链接去下载相应的文件，最终在/etc/ros/rosdep下放5个文件，分别是base.yaml,gentoo.yaml,osx-homebrew.yaml,python.yaml,ruby.yaml. 但又做了一些配置，所以不是下载文件能解决的。

以下步骤先从网上下载rosdistro文件夹，放到/etc/ros

执行`sudo rosdep init`后报错

1 2	ERROR: cannot download default sources list from: https://raw.githubusercontent.com/ros/rosdistro/master/rosdep/sources.list.d/20-default.list Website may be down

从网上直接下载这个文件，然后放到/etc/ros/rosdep/sources.list.d，再修改如下:

# os-specific listings first

yaml file:///etc/ros/rosdistro/rosdep/osx-homebrew.yaml osx

# generic
yaml file:///etc/ros/rosdistro/rosdep/base.yaml
yaml file:///etc/ros/rosdistro/rosdep/python.yaml
yaml file:///etc/ros/rosdistro/rosdep/ruby.yaml
gbpdistro file:///etc/ros/rosdistro/releases/fuerte.yaml fuerte

# newer distributions (Groovy, Hydro, ...) must not be listed anymore, they are being fetched from the rosdistro index.yaml instead

rosdep update 报错

kinetic 要修改python2.7的路径, melodic和noetic要修改python3 ，当然另一种方法是从其他电脑拷贝已经生成的文件。

kinetic 的修改

1 2	reading in sources list data from /etc/ros/rosdep/sources.list.d ERROR: unable to process source

对下面三个文件做修改

/usr/lib/python2.7/dist-packages/rosdep2/gbpdistro_support.py
修改: FUERTE_GBPDISTRO_URL = 'file:///etc/ros/rosdistro/releases/fuerte.yaml'


/usr/lib/python2.7/dist-packages/rosdep2/rep3.py
修改: REP3_TARGETS_URL = 'file:///etc/ros/rosdistro/releases/targets.yaml'


/usr/lib/python2.7/dist-packages/rosdistro/__init__.py
修改: DEFAULT_INDEX_URL = 'file:///etc/ros/rosdistro/index-v4.yaml'

启动新终端，再次执行rosdep update

melodic和noetic 的修改：clone代码仓https://github.com/ros/rosdistro到本地，并更改其文件rosdep/sources.list.d/20-default.list，将其url改成本地文件路径，内容类似如下：

# os-specific listings first
yaml file:///home/baby/rosdistro/rosdep/osx-homebrew.yaml osx

# generic
yaml file:///home/baby/rosdistro/rosdep/base.yaml
yaml file:///home/baby/rosdistro/rosdep/python.yaml
yaml file:///home/baby/rosdistro/rosdep/ruby.yaml
gbpdistro file:///home/baby/rosdistro/releases/fuerte.yaml fuerte

由于rosdep使用python3，可直接该动源码。我们需要改动三个文件：

/usr/lib/python3/dist-packages/rosdep2/sources_list.py，修改 DEFAULT_SOURCES_LIST_URL = 'file:///home/baby/rosdistro/rosdep/sources.list.d/20-default.list'
/usr/lib/python3/dist-packages/rosdep2/rep3.py，修改 REP3_TARGETS_URL = 'file:///home/baby/rosdistro/releases/targets.yaml'
/usr/lib/python3/dist-packages/rosdep2/gbpdistro_support.py，修改 FUERTE_GBPDISTRO_URL = 'file:///home/baby/rosdistro/releases/fuerte.yaml'
/usr/lib/python3/dist-packages/rosdistro/__init__.py，修改 DEFAULT_INDEX_URL = 'file:///home/baby/rosdistro/index-v4.yaml'

完成后先把/etc/ros/rosdep/sources.list.d/20-default.list删除，再执行sudo rosdep init与rosdep update就可以成功了。

参考:
解决 rosdep update

执行sudo rosdep init后报错

rosdep update 报错

执行`sudo rosdep init`后报错