This REP describes a "rosdep 2" tool that is significantly different from its predecessor . This new version uses a "sources list", similar in semantics to the apt tool . It is also a standalone tool that can be separately installed and used with or without a ROS package system.
This specification is meant to be minimal. See "Future Improvements" for possible extensions.
The example workflows below provide a high-level sketch of how rosdep 2 is used. The main differences are:
- Standalone installation.
- Installation requires an init and update step to create the local database.
- More querying APIs.
sudo pip install -U rosdep sudo rosdep init rosdep update
Common installation workflow:
$ rosdep check ros_comm All system dependencies have been satisified $ rosdep install geometry
$ rosdep keys roscpp pkg-config $ rosdep resolve pkg-config pkg-config $ rosdep keys geometry eigen apr glut python-sip python-numpy graphviz paramiko cppunit libxext log4cxx pkg-config $ rosdep resolve eigen libeigen3-dev
rosdep 2 loads valid data sources specified in the sources list in order. This follows the behavior of apt, which designates the "most preferred source listed first."
Each rosdep entry from the data sources is combined into a single rosdep database. Entries from data sources listed higher in the sources have higher precedence.
A data source is considered valid if all of its tags match the local tags. A data source with no tags is always loaded.
There are no longer conflicts in rosdep 2. rosdep.yaml files are processed in order of precedence, with the first entry for a rosdep key "winning". Subsequent entries for the same key, even if they are non-conflicting, are not merged.
rosdep 2 always loads its database from a local cache. The user must explicitly update this local cache to get new resolution rules.
A .list file lists data sources, with the most preferred data source first. The general format is:
source-type uri [tags...]
Where source-type can be:
Lines that start with a # are considered to be comments.
yaml https://github.com/ros/rosdistro/raw/master/rosdep/base.yaml yaml https://github.com/ros/rosdistro/raw/master/rosdep/python.yaml gbpdistro https://github.com/ros/rosdistro/raw/master/releases/fuerte.yaml fuerte
gbpdistro refers to a git-buildpackage-based toolchain currently in use for building REP 122-compliant stacks. This toolchain is still in a prototype phase; thus, this gbpdistro specification is unstable.
This REP does not define the gbpdistro format, but it is assumed to be a YAML file with that conforms to:
gbp-repos: - name: NAME1 target: all url: git://github.com/PROJECT1/REPO1.git - name: NAME2 target: [lucid, oneiric] url: git://github.com/PROJECT2/REPO2.git release-name: RELEASE-NAME
rosdep 2 can create a data source based on a gbpdistro file. For each entry in the gbp-repos key, rosdep 2 produces a rosdep key for NAME that maps to the Ubuntu package name ros-<RELEASE-NAME>-<NAME>. In the future, this mechanism could also be used to produce rosdep key mappings for other platforms, like OS X Homebrew.
rosdep 2 uses a "targets" file that provides a lookup table for resolving all targets based on RELEASE-NAME. The targets files is a machine-readable representation of REP 3 .
rosdep 2 uses a similar definition as apt sources.list.d :
The /etc/ros/rosdep/sources.list.d directory provides a way to add entries in separate files. File names need to end with .list and may only contain letters (a-z and A-Z), digits (0-9), underscore (_), hyphen (-) and period (.) characters. Otherwise they will be silently ignored.
For simplicity, we don't implement an /etc/ros/rosdep/sources.list and instead soley use the /etc/ros/rosdep/sources.list.d/ implementation, which is much easier for idempotent configuration by scripts.
No longer takes in any arguments and uses the easier to type db instead of depdb. The database that is used to resolve rosdep keys is determined by the sources list, and thus is not dependent on a particular resource (e.g. ROS package or stack). The previous depdb command is still processed but not promoted.
Both commands are the same as their predecessors, but use a more consistent dash separator. The previous versions are supported but not promoted.
Initializes a default /etc/ros/rosdep/sources.list.d directory for the user. This is a bootstrapping command that only needs to be run once, most likely as:sudo rosdep init
List the rosdep keys that the ROS stacks and packages depend on. This command only works with a ROS_PACKAGE_PATH set.
Prints the resolution of the listed rosdeps to the console. This enables users to easily query rosdep and verify its behavior. It is meant to be used together with the keys command.
Processes /etc/ros/rosdep/sources.list.d and downloads new datafiles for the local database. This is the only command that examines remote sources. All other commands are processed against local data.
The original rosdep gave preference to the developer of a ROS stack. It enabled that developer to declare dependency rules and distribute them with the stack. As a corollary, it strongly favored reproducibility and correctness: old source trees could be checked out and be built the same way. As a result of these goals, rosdep rules were stored with code. Also, aggregation of rules in lower-level stacks was frowned upon, as it would restrict downstream developers
This design has not scaled very well. There are several issues, in particular, that have strongly motivated a redesign:
The rosdep 2 design favors the end-user as well as maintainers of software distributions. The main goals of rosdep 2 are:
- Clarity of resolution.
- Easily end-user control over rosdep resolution.
The semantics of Ubuntu's apt tool are followed as much as possible to provide familiarity.
The main incompatibility is rosdep 2 does not read rosdep.yaml files from ROS stacks. It only loads from data sources in the sources list.
There are minor incompatibilities in the command-line API. The main installation commands are also the same, so many scripts based on rosdep are likely to continue to work. However, the new rosdep command requires an initialization/update step to create the rosdep database, which may cause some initial incompatibilities. Scripts that use rosdep and run on freshly installed machines, such as chroots, will be especially effected.
The output format of some commands, like db and where-defined have been changed for clarity and easier processing. As far as the author knows, no scripts depend on the output format of these commands.
For example, rosdep 1:
$ rosdep where_defined eigen eigen defined in set(['/opt/ros/electric/stacks/common_rosdeps/rosdep.yaml', ">>/opt/ros/electric/stacks/common_rosdeps/rosdep.yaml<<Unused due to package 'common_rosdeps' being in a stack.]]"])
$ rosdep where-defined eigen https://github.com/ros/rosdistro/raw/master/rosdep/base.yaml
rosmake no longer has options for invoking rosdep internally as rosdep is now an external tool.
Although the querying APIs go beyond the minimal specification necessary for rosdep 2, they were useful in its development as they provide command-line verification of the resolution behavior. For the same reasons, the new querying APIs make rosdep's behavior more clear to the end user. Users can see the rosdep keys that are tied to a particular ROS package. The user can also see how those keys relate to system dependencies prior to performing installation.
The new rosdep eschews conflict in favor of clarity. A particular rosdep entry always comes from a single source, and the source that is chosen is the one that is ranked highest. An alternative would have been to merge compatible rules for a rosdep key, such as rules that have non-intersecting OSes. This would mean that entries could come from multiple sources, which is less clear.
The initial reference implementation loaded rosdep.yaml files from stacks as well, but it increased confusion. Based on the specific implementation:
Either of these conflicts with the goal of providing clear resolution to the user. Furthermore, it requires maintaining dual sets of rosdep.yaml files.
rosdep 2 does not obey the ROS_ETC_DIR environment variable defined in REP 124 . This decision was made for four reasons:
- Confusing behavior with rosdep init, which is run under sudo and thus would require an extra command-line arguments to preserve environment variables.
- Conflicts with goal of clarity. rosdep always uses the same local database.
- "tags" in the .list file format implicitly support multiple distributions.
- rosdep 2 is a standalone tool not included with any ROS distribution.
The following rosdep command take in <stacks-and-packages> as arguments:
In order to support rosdep as its own standalone tool, it is easy to imagine extending each of those commands to take rosdep keys as well.
This improvement has strong synergy with ROS Fuerte, which transitions lower-level stacks to be rosdep keys. For example, ros_comm is both a stack name and a rosdep key.
The rosdep init and rosdep update commands will likely need more configurability than their current bare specification provide. For example, it will be desirable to configure them to use a different sources list than /etc/ros/rosdep/sources.list.d.
The rosdep2 package provides a reference implementation of this specification. It can be installed via pip:
sudo pip install -U rosdep
A Git repository is available at https://github.com/ros-infrastructure/rosdep.
The reference implementation is not yet fully compatible with this specification.
|||rosdep wiki page (http://ros.org/wiki/rosdep)|
|||(1, 2) sources.list man page (http://manpages.debian.net/cgi-bin/man.cgi?query=sources.list&sektion=5&apropos=0&manpath=Debian+Sid&locale=en)|
|||(1, 2) REP 111: Multiple Package Manager Support for Rosdep (http://ros.org/reps/rep-0111.html)|
|||rosdep YAML format (http://ros.org/doc/independent/api/rosdep/html/rosdep_yaml_format.html)|
|||REP 122: FHS layout for ROS installation (http://ros.org/reps/rep-0122.html)|
|||REP 123: ROS_ETC_DIR, ROS_DISTRO environment variables and ROS_ROOT changes (http://ros.org/reps/rep-0123.html)|
|||REP 3: Target Platforms (http://ros.org/reps/rep-0003.html)|
This document has been placed in the public domain.