Dependencies

Servers

Dependency	Version	Ubuntu Package(s)	Description
PostgreSQL	8.3+	postgresql	Robust RDBMS. Used as primary data store.
Cassandra	0.7.2+	cassandra in ppa:cassandra-ubuntu	Distributed database. Slowly becoming primary data store.
memcached	1.4+	memcached	Fast in-memory caching server. Used throughout reddit.
RabbitMQ	2.0+	rabbitmq-server	AMQP server. Used for offline processing.
HAProxy		haproxy	Load balancer for distributing requests to app servers.

Libraries

Dependency	Version	Ubuntu Package(s)	Description
Python	2.7.x	python-dev	Headers for building python modules.
Setuptools		python-setuptools	Provides easy_install and support for setup.py.
Profiler		python-profiler	Enables reddit app to provide profile information.
PIL		python-imaging	Used for image manipulation (thumbnails, CAPTCHAs, etc.)
libmemcached	0.32+	libmemcached5 and libmemcached-dev	For communication with memcached.
libpqxx		libpqxx-dev	C++ library for PostgreSQL.
gettext		gettext	Used for i18n support.

Misc. Utilities

Dependency	Version	Ubuntu Package(s)	Description
Git		git-core	reddit code is stored in Git.
GCC / G++		g++	GNU C++ Compiler. Used for compiling python modules etc.
Cython		cython	Performance-intensive code is in Cython for speed.
Subversion		subversion	Needed to install some python dependencies.
daemontools		daemontools and daemontools-run	Simple daemon management system.
optipng		optipng	Used to compress auto-generated CSS spritemap.
psql		postgresql-client	CLI client for managing PostgreSQL.