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These instructions will guide you through the process of setting up a reddit clone for the first time. We also have an automated install script for Ubuntu Linux 12.04.

Prerequisites

Before continuing with this guide, make sure you have all of reddit's many dependencies installed.

This guide will assume that you are installing reddit as user reddit in the directory /home/reddit. If this is not the case, modify the examples accordingly.

Get the code

Clone the git repository available here on github.

$ git clone https://github.com/reddit/reddit.git

Once this is done, you'll need to install the python module dependencies.

$ cd reddit/r2
$ python setup.py build
$ sudo python setup.py develop
$ make

The setup.py develop command only needs to be run at installation time, but the Makefile will need to be rerun any time you modify a Cython file (*.pyx) so that the code can be compiled.

PostgreSQL

PostgreSQL is reddit's primary data store. It is used for storing data on Accounts, Subreddits, Links, Comments, Votes, etc. In production, we use many separate database clusters, but for sites with less traffic (or test instances) a single postgres database should suffice.

This guide assumes you have a working PostgreSQL install running under the unix user postgres, and that you can access it with sudo -u postgres psql. That's the norm if you installed PostgreSQL on Ubuntu/Debian/Fedora from operating system packages, and on Mac OS X using Homebrew. To test that, copy and paste the following command to your terminal and run it:

sudo -u postgres psql -qAt -c "SELECT 'connected ok, superuser: ' || (select usesuper from pg_user where usename = CURRENT_USER)||', version: '||version()"

It should print something like:

connected ok, superuser: true, version: PostgreSQL 9.3.1

You want "superuser: true", since you'll be doing some database setup tasks.

Make sure the PostgreSQL version printed is a reasonable, supported version; see PostgreSQL's version policy. Mac OS X users need to be particularly wary that the version printed is the same as the version they think they installed, as Apple installs an old version of PostgreSQL as part of Mac OS X.

If you installed PostgreSQL from source code instead of operating system packages or an installer you might need to create a database cluster first, as well as install the appropriate startup scripts. It's generally much better to install PostgreSQL from operating system packages. If your OS has only very old versions of PostgreSQL, see the PostgreSQL download page for alternatives, including deb (apt) and rpm (yum) packages.

Create the database

Create a database for reddit's data.

$ sudo -u postgres createdb -E utf8 reddit

And a user for the code to connect with.

$ sudo -u postgres psql reddit
> CREATE USER reddit WITH PASSWORD 'password';
> \q

Then add reddit's SQL functions to the schema.

$ cd ~/reddit/
$ sudo -u postgres psql reddit < sql/functions.sql

Cassandra

Cassandra is a vital component the reddit architecture that stores many pieces of data used throughout the site.

You must create the keyspace for reddit and the permacache column family.

$ cassandra-cli -h localhost
[default@unknown] create keyspace reddit;
[default@unknown] use reddit;
[default@unknown] create column family permacache with column_type = 'Standard' and comparator = 'BytesType';

The reddit application will create the rest of the required column families automatically.

RabbitMQ

RabbitMQ is used for asynchronous job processing. Jobs are pushed onto a set of queues by user actions (such as creating a post or comment) for tasks that need not be done during the POST. As such, in addition to getting rabbit running, there are a set of services responsible for removing jobs from these queues covered under the services section.

Configuration of rabbit is relatively simple.

$ sudo rabbitmqctl add_vhost /
$ sudo rabbitmqctl add_user reddit reddit
$ sudo rabbitmqctl set_permissions -p / reddit ".*" ".*" ".*"

memcached

Almost everything in reddit depends on memcached running, and you won't be able to do much without it.

Most package managers will set up run scripts for memcached automatically. To check if it is already running, use telnet.

$ telnet localhost 11211

If that is unable to connect, you must start the memcache daemon.

$ memcached 

Test your installation

Before continuing, make sure that reddit is able to start up and connect to the databases.

$ cd ~/reddit/r2
$ paster serve --reload example.ini http_port=8081

You should be able to access reddit at http://127.0.0.1:8081/.

Troubleshooting

Following are some of the more commonly seen problems at this point in the installation.

Error Resolution
ImportError: No module named wrapped You need to compile the Cython modules. ```bash $ cd ~/reddit/r2 $ make ```
(OperationalError) FATAL: password authentication failed for user "reddit" The postgres user "reddit" has the wrong password. You should recreate the postgres user "reddit" with password "password". ```bash reddit$ su postgres postgres$ dropuser reddit postgres$ createuser -P reddit ```

Populate with test data

For testing purposes, you can generate random test data for your reddit install.

$ cd ~/reddit/r2
$ paster shell example.ini
>>> from r2.models import populatedb
>>> populatedb.populate()

Note: this will also create a reddit account named reddit with password password.

Services and Cron Jobs

Configuration

In ~/reddit/r2, there is a script called updateini.py which reads ini files and applies differences from a specified .update file. This means that you can make changes to the provided example.ini by modifying a .update file without worrying about merge issues down the line.

To take advantage of this infrastructure do the following.

$ cd ~/reddit/r2
$ touch run.update
$ make

Services

reddit's various services are managed with Upstart. You need a little bit of configuration to get started, change the settings according to your configuration:

# cat > /etc/default/reddit <<REDDIT
export REDDIT_ROOT=$REDDIT_HOME/reddit
export REDDIT_INI=$REDDIT_HOME/reddit/r2/run.ini
export REDDIT_USER=$REDDIT_USER
export REDDIT_CONSUMER_CONFIG=$REDDIT_HOME/consumer-counts.d
alias wrap-job=$REDDIT_HOME/reddit/scripts/wrap-job
alias manage-consumers=$REDDIT_HOME/reddit/scripts/manage-consumers
REDDIT

Create the consumer-counts.d directory mentioned above. For each asynchronous job queue, create a file with the queue job's name in it in the consumer-counts.d directory and make the contents of the file the number of processors to run. For example:

$ cd $REDDIT_HOME/consumer-counts.d
$ echo 1 > scraper_q
$ echo 1 > commentstree_q
$ echo 1 > newcomments_q
$ echo 1 > vote_comment_q
$ echo 1 > vote_link_q

Then, copy the job configuration files from the upstart/ directory to /etc/init.

$ sudo cp ~/reddit/upstart/* /etc/init/

You can then start up all the processors with:

$ sudo initctl emit reddit-start

Crons

There are several jobs that need to be run periodically to update the site. These jobs are also managed with upstart. Following is a recommended cron setup. See Cron Jobs for information on what each of these does.

0    3 * * * root /sbin/start --quiet reddit-job-update_sr_names
30  16 * * * root /sbin/start --quiet reddit-job-update_reddits
0    * * * * root /sbin/start --quiet reddit-job-update_promos
*/5  * * * * root /sbin/start --quiet reddit-job-clean_up_hardcache
*    * * * * root /sbin/start --quiet reddit-job-email
*/2  * * * * root /sbin/start --quiet reddit-job-broken_things
*/2  * * * * root /sbin/start --quiet reddit-job-rising

Troubleshooting

Check the FAQ for help with any issues you may be encountering at this point.

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