Installation

Supported Platforms

Python 2.6, 2.7, 3.3, and 3.4 are supported. Both CPython (the standard Python implementation) and PyPy are supported and tested.

Linux, OSX, and Windows are supported.

Installation through pip

pip is the suggested tool for installing packages. It will handle installing all Python dependencies for the driver at the same time as the driver itself. To install the driver*:

pip install cassandra-driver

You can use pip install --pre cassandra-driver if you need to install a beta version.

*Note: if intending to use optional extensions, install the dependencies first. The driver may need to be reinstalled if dependencies are added after the initial installation.

OSX Installation Error

If you’re installing on OSX and have XCode 5.1 installed, you may see an error like this:

clang: error: unknown argument: '-mno-fused-madd' [-Wunused-command-line-argument-hard-error-in-future]

To fix this, re-run the installation with an extra compilation flag:

ARCHFLAGS=-Wno-error=unused-command-line-argument-hard-error-in-future pip install cassandra-driver

Windows Installation Notes

Installing the driver with extensions in Windows sometimes presents some challenges. A few notes about common hang-ups:

Setup requires a compiler. When using Python 2, this is as simple as installing this package (this link is also emitted during install if setuptools is unable to find the resources it needs). Depending on your system settings, this package may install as a user-specific application. Make sure to install for everyone, or at least as the user that will be building the Python environment.

It is also possible to run the build with your compiler of choice. Just make sure to have your environment setup with the proper paths. Make sure the compiler target architecture matches the bitness of your Python runtime. Perhaps the easiest way to do this is to run the build/install from a Visual Studio Command Prompt (a shortcut installed with Visual Studio that sources the appropriate environment and presents a shell).

Manual Installation

You can always install the driver directly from a source checkout or tarball. When installing manually, ensure the python dependencies are already installed. You can find the list of dependencies in requirements.txt.

Once the dependencies are installed, simply run:

python setup.py install

Verifying your Installation

To check if the installation was successful, you can run:

python -c 'import cassandra; print cassandra.__version__'

It should print something like “2.7.0”.

(Optional) Compression Support

Compression can optionally be used for communication between the driver and Cassandra. There are currently two supported compression algorithms: snappy (in Cassandra 1.2+) and LZ4 (only in Cassandra 2.0+). If either is available for the driver and Cassandra also supports it, it will be used automatically.

For lz4 support:

pip install lz4

For snappy support:

pip install python-snappy

(If using a Debian Linux derivative such as Ubuntu, it may be easier to just run apt-get install python-snappy.)

(Optional) Metrics Support

The driver has built-in support for capturing Cluster.metrics about the queries you run. However, the scales library is required to support this:

pip install scales

(Optional) Non-python Dependencies

The driver has several optional features that have non-Python dependencies.

C Extensions

By default, a number of extensions are compiled, providing faster hashing for token-aware routing with the Murmur3Partitioner, libev event loop integration, and Cython optimized extensions.

When installing manually through setup.py, you can disable both with the --no-extensions option, or selectively disable them with with --no-murmur3, --no-libev, or --no-cython.

To compile the extensions, ensure that GCC and the Python headers are available.

On Ubuntu and Debian, this can be accomplished by running:

$ sudo apt-get install gcc python-dev

On RedHat and RedHat-based systems like CentOS and Fedora:

$ sudo yum install gcc python-devel

On OS X, homebrew installations of Python should provide the necessary headers.

See Windows Installation Notes for notes on configuring the build environment on Windows.

Cython-based Extensions

By default, this package uses Cython to optimize core modules and build custom extensions. This is not a hard requirement, but is engaged by default to build extensions offering better performance than the pure Python implementation.

This is a costly build phase, especially in clean environments where the Cython compiler must be built This build phase can be avoided using the build switch, or an environment variable:

python setup.py install --no-cython

Alternatively, an environment variable can be used to switch this option regardless of context:

CASS_DRIVER_NO_CYTHON=1 <your script here>
- or, to disable all extensions:
CASS_DRIVER_NO_EXTENSIONS=1 <your script here>

This method is required when using pip, which provides no other way of injecting user options in a single command:

CASS_DRIVER_NO_CYTHON=1 pip install cassandra-driver
CASS_DRIVER_NO_CYTHON=1 sudo -E pip install ~/python-driver

The environment variable is the preferred option because it spans all invocations of setup.py, and will prevent Cython from being materialized as a setup requirement.

If your sudo configuration does not allow SETENV, you must push the option flag down via pip. However, pip applies these options to all dependencies (which break on the custom flag). Therefore, you must first install dependencies, then use install-option:

sudo pip install six futures
sudo pip install --install-option="--no-cython"

libev support

The driver currently uses Python’s asyncore module for its default event loop. For better performance, libev is also supported through a C extension.

If you’re on Linux, you should be able to install libev through a package manager. For example, on Debian/Ubuntu:

$ sudo apt-get install libev4 libev-dev

On RHEL/CentOS/Fedora:

$ sudo yum install libev libev-devel

If you’re on Mac OS X, you should be able to install libev through Homebrew. For example, on Mac OS X:

$ brew install libev

The libev extension is not built for Windows (the build process is complex, and the Windows implementation uses select anyway).

If successful, you should be able to build and install the extension (just using setup.py build or setup.py install) and then use the libev event loop by doing the following:

>>> from cassandra.io.libevreactor import LibevConnection
>>> from cassandra.cluster import Cluster

>>> cluster = Cluster()
>>> cluster.connection_class = LibevConnection
>>> session = cluster.connect()

(Optional) Configuring SSL

Andrew Mussey has published a thorough guide on Using SSL with the DataStax Python driver.