Spread

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Note: this is an internal document intended for Wikimedia system administrators and is not intended for a general audience

Spread is the application-level multicast backend for wackamole.

Installation

• Download from http://www.spread.org
• ./configure ; make
• make install as root
• remove the default configuration file from /usr/local/etc/spread.conf and replace it with a symlink, ln -s /home/wikipedia/conf/spread/spread.conf /usr/local/etc/spread.conf
• Add a spread user and group
  • groupadd -g114 spread
  • useradd -u114 -s/sbin/nologin -gspread spread
• Create directory for it to chroot into, don't ask me why it doesn't do this itself
  • mkdir -m660 /var/run/spread
  • chown spread:wikidev /var/run/spread
• Start the daemon with nohup /usr/local/bin/spread&
• Add the above line to rc.local

Configuration

Spread seems to pick an IP address randomly and demand that its broadcast domain be in spread.conf. Well maybe not quite randomly, since it seems to pick the 10/8 one. Anyway, the format is fairly self-explanatory, there's a broadcast domain and a list of hosts.