Hacking Python SDK » History » Version 10

Version 9 (Tom Clegg, 08/08/2014 11:30 AM) → Version 10/23 (Brett Smith, 08/13/2014 01:38 PM)

h1. Hacking Python SDK

{{toc}}

h2. Prerequisites

The FUSE driver requires associated libraries to build:

<pre>
sudo apt-get install libattr1-dev libfuse-dev pkg-config fuse
sudo adduser "$USER" fuse
sudo chmod g+rw /dev/fuse
sudo chown root:fuse /dev/fuse
</pre>

After installing @fuse@ and adding yourself to the @fuse@ group, you need to start a new login session. Make sure the @groups@ command reports that you're in the @fuse@ group.

h2. Get the source code

<pre>
cd
git clone https://github.com/curoverse/arvados.git
</pre>

h2. virtualenv

virtualenv helps you isolate the dependencies for a specific package or environment, much like Bundler does for our Rails applications. The recommended way to deploy is to build a virtualenv for Arvados development.

To build the virtualenv, run:

<pre>
$ virtualenv --setuptools VENVDIR
</pre>

(@VENVDIR@ can be a directory anywhere you like, although best practice is to keep it outside your source directory.)

To set up the shell to use the isolated virtualenv environment, run:

<pre>
$ source VENVDIR/bin/activate
</pre>

To learn more about using and configuring virtualenv, read the "virtualenv usage documentation":https://virtualenv.pypa.io/en/latest/virtualenv.html#usage.



h2. Run tests

Strategy:
# Set up the environment to use a dedicated virtualenv
# Run the client library test suite
# Build a client library package and install it to the virtualenv
# Run the FUSE driver test suite
# Build a FUSE driver package and install it to the virtualenv

Note: The test suite brings up a Keep server and an API server to run tests against. For best results:
* Try [[Hacking Keep]] and [[Hacking API Server]] to make sure you have all the right dependencies for running the Keep and API servers.
* Make sure you have a blob_signing_key in services/api/config/application.yml
* Build Keep binary. @cd .../arvados/services/keep; ./go.sh install keep@

Script (make sure to edit the first line to refer to your virtualenv):

<pre>
source VENVDIR/bin/activate

cd ~/arvados/sdk/python
python setup.py test
python setup.py egg_info -b ".$(git log --format=format:%ct.%h -n1 .)" sdist rotate --keep=1 --match .tar.gz
pip install dist/arvados-python-client-0.1.*.tar.gz

cd ~/arvados/services/fuse
python setup.py test
python setup.py egg_info -b ".$(git log --format=format:%ct.%h -n1 .)" sdist rotate --keep=1 --match .tar.gz
pip install dist/arvados_fuse-0.1.*.tar.gz
</pre>

h2. Logging

The Python SDK uses Python's built-in logging module to log errors, warnings, and debug messages. The arvados module sets up logging for messages under "arvados" based on local configuration (e.g., the @ARVADOS_DEBUG@ setting). Other SDK modules and command-line tools should @import arvados@ and then send messages to a logger under "arvados" to ensure consistent log handling. Typical setup looks like this:

<pre><code class="python">
import arvados
import logging

logger = logging.getLogger('arvados.YOURTHING')
</code></pre>

Once you've set this up, you can send messages to the logger using methods like @logger.debug()@ and @logger.error()@. See the "Logger class documentation":https://docs.python.org/2/library/logging.html#logger-objects for full details.

Command-line scripts may reconfigure the @arvados.logger@ object based on additional configuration like command-line switches. @services/fuse/bin/arv-mount@ demonstrates adjusting the level and setting a custom log handler.