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galaxy/doc/source/admin/dependency_resolvers.rst
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John Chilton 1148081435 Implement a conda dependency resolver.
Much more information on planemo PR that I used to build a test bed for this:

https://github.com/galaxyproject/planemo/pull/392

Also syncs galaxy with planemo shared library changed.
2015-12-26 22:46:28 +00:00

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Dependency Resolvers in Galaxy
==============================
There are two parts to building a link between Galaxy and command line bioinformatics tools: the tool XML that
specifies a mapping between the Galaxy web user interface and the tool command line and tool dependencies that specify
how to source the actual packages that implement the tool’s commands. The final script that Galaxy submits to run a
job uses includes commands, such as changes to the ``PATH`` environment variable, that are generated by *dependency
resolvers*. There is a default dependency resolver configuration but administrators can provide their own configuration
using the ``dependency_resolvers_conf.xml`` configuration file in the Galaxy ``config/`` directory.
The binding between tool XML and the tools they need to run is specified in the tool XML using *requirements*
tags, for example
.. code-block:: xml
<requirement type="package" version="0.7.10.039ea20639">bwa</requirement>
In some cases these requirement tags can be specified without a version
.. code-block:: xml
<requirement type="package">bedtools</requirement>
The requirement turn into inputs to the dependency resolver. Each dependency resolver is thus given given one or
two inputs: the name of the dependency to resolve and, in most cases, the version string of the
dependency.
Default Dependency Resolvers
----------------------------
The default configuration of dependency resolvers is equivalent to the following ``dependency_resolvers_conf.xml``
.. code-block:: xml
<dependency_resolvers>
<!-- the default configuration, first look for dependencies installed from the toolshed -->
<tool_shed_packages />
<!-- then look for env.sh files profile according to the "galaxy packages" schema -->
<galaxy_packages />
<galaxy_packages versionless="true" />
<conda />
<conda versionless="true" />
</dependency_resolvers>
This default dependency resolver configuration contains three items. First, the *tool shed dependency resolver* is used,
then the *Galaxy packages dependency resolver* is used, first looking for packages by name and version string and then
finally looking for the package just by name. The default configuration thus prefers packages installed from the Galaxy
Tool Shed, before trying to find a "Galaxy package" satisfying the specific version the dependency requires before
finally falling back to looking for a Galaxy package with merely the correct name. If any of the dependency
resolvers succeeds a dependency resolution object is returned and no more resolvers are called. This dependency
resolution object provides shell commands to prepend to the shell script that runs the tool.
Tool Shed Dependency Resolver
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
The ``tool_shed_packages`` dependency resolver works with packages installed from the Galaxy Tool Shed. When a package
is installed from the Tool Shed it creates a directory structure under the directory that is specified as the
``tool_dependency_dir`` in Galaxy's configuration. This directory structure contains references to the tool's name,
owner (in the Tool Shed) and version string (amongst other things) and ultimately contains a file named ``env.sh``
that contains commands to make the dependency runnable. This is installed, along with the packaged tool, by the tool
package and doesn't require any configuration by the Galaxy administrator.
The Tool Shed dependency resolver is not able to resolve package requirements that do not have a version string,
like the `bedtools` example above.
Galaxy Packages Dependency Resolver
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
The ``galaxy_packages`` dependency resolver allows Galaxy admins to specify how Galaxy should load manually
installed packages. This resolver can be configured either to use the version string or in *versionless* mode.
The Galaxy Packages dependency resolver takes a ``base_path`` argument that specifies the path under which
it starts looking for the files it requires. The default value for this ``base_path`` is the
``tool_dependency_dir`` configured in Galaxy's ``config/galaxy.ini``. Below the base path, the Galaxy Packages
resolver looks for directories named after tools, e.g. ``bedtools``. As mentioned before, this resolver
works in versioned and versionless mode. The default mode is versioned, where the dependency resolver looks for a
directory named after the dependency's version string. For example, if the Galaxy tool specifies that it
needs ``bedtools`` version 2.20.1, the dependency resolver will look for a directory ``bedtools/2.20.1``.
If the Galaxy Package dependency resolver finds a ``bin`` directory in this directory, it adds it to the ``PATH``
used by the scripts Galaxy uses to run tools. If, however, it finds an ``env.sh`` script, it sources this
script before running the tool that requires this dependency. This can be used to set up the environment
needed for the tool to run. For example, this ``env.sh`` uses `Environment Modules <http://modules.sourceforge.net/>`_
to setup the environment for ``bedtools``
.. code-block:: bash
#!/bin/sh
if [ -z "$MODULEPATH" ] ; then
. /etc/profile.d/module.sh
fi
module add bedtools/bedtools-2.20.1
The Galaxy Package dependency resolver operates quite similarly when used in versionless module. Instead of looking
for a directory named after a version, it looks for a directory ending in ``default``. For example
``bedtools/default``. It then looks for a `bin` subdirectory or ``envh.sh`` and incorporates these in the tool
script that finally gets run. This versionless (i.e. default) lookup is also used if the package requirement
does not specify a version string.
Environment Modules Dependency Resolver
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
The example above used Environment Modules to set the ``PATH`` (and other settings) for ``bedtools``. With
the ``modules`` dependency resolver it is possible to use Environment Modules directory. This resolver
takes these parameters:
modulecmd
path to Environment Modules' ``modulecmd`` tool
modulepath
value used for MODULEPATH environment variable, used to locate modules
versionless
whether to resolve tools using a version string or not (default: *false*)
find_by
whether to use the ``DirectoryModuleChecker`` or ``AvailModuleChecker`` (permissable values are "directory" or "avail",
default is "avail")
prefetch
in the AvailModuleChecker prefetch module info with ``module avail`` (default: true)
default_indicator
what indicate to the AvailModuleChecker that a module is the default version (default: "(default)"). Note
that the first module found is considered the default when no version is used by the resolver, so
the sort order of modules matters.
The Environment Modules dependency resolver can work in two modes. The ``AvailModuleChecker`` searches the results
of the ``module avail`` command for the name of the dependency. If it is configured in versionless mode,
or is looking for a package with no version specified, it accepts any module whose name matches and is a bare word
or the first module whose name matched. For this reason, the default version of the module should be the first one
listed, something that can be achieved by tagging it with a word that appears first in sort order, for example the
string "(default)" (yielding a module name like ``bedtools/(default)``). So when looking for ``bedtools`` in
versionless mode the search would match the first module called ``bedtools``, and in versioned mode the search would
only match if a module named ``bedtools/2.20.1`` was present (assuming you're looking for ``bedtools/2.20.1``).
The``DirectoryModuleChecker`` looks for files or directories in the path specified by ``MODULEPATH`` or
``MODULESHOME`` that match the dependency being resolved. In versionless mode a match on simply
the dependency name is needed, and in versioned mode a match on the dependency name and
version string is needed.
If a module matches the dependency is found, code to executed ``modulecmd sh load`` with the name of the dependency
is added to the script that is run to run the tool. E.g. ``modulecmd sh load bedtools``. If version strings are being
used, they'll be used in the ``load`` command e.g. ``modulecmd sh load bwa/0.7.10.039ea20639``.
Homebrew Dependency Resolver
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
This dependency resolver uses homebrew packages to resolve requirements.
Brew Tool Shed Package Resolver
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
This dependency resolver would resolve tool shed packages that had been
auto converted to the tool shed. It is highly experimental, undocumented,
and will almost certainy be removed from the code base.
Conda Dependency Resolver
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
The conda XML tag can be used to configure a conda dependency resolver.
This resolver can be configured with the following options.
prefix
The conda_prefix used to locate dependencies in (default: ``<tool_dependency_dir>/_conda``).
exec
The conda executable to use, it will default to the one on the
PATH (if available) and then to ``<conda_prefix>/bin/conda``.
versionless
whether to resolve tools using a version string or not (default: *false*)
debug
Pass debug flag to conda commands (default: false).
ensure_channels
conda channels to enable by default. See
http://conda.pydata.org/docs/custom-channels.html for more
information about channels. (default: r,bioconda).
auto_install
Set to True to instruct Galaxy to look for and install missing tool
dependencies before each job runs. (default: False)
auto_init
Set to True to instruct Galaxy to install conda from the web
automatically if it cannot find a local copy and conda_exec is not
configured.