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|
#!/bin/sh
#
# This script installs and configures the Serf agent that runs on
# every node. As with the other scripts, this should probably be done with
# formal configuration management, but a shell script is simple as well.
#
# The SERF_ROLE environmental variable must be passed into this script
# in order to set the role of the machine. This should be either "lb" or
# "web".
#
set -e
sudo apt-get install -y unzip
# Download and install Serf
cd /tmp
until wget -O serf.zip https://dl.bintray.com/mitchellh/serf/0.6.4_linux_amd64.zip; do
sleep 1
done
unzip serf.zip
sudo mv serf /usr/local/bin/serf
# The member join script is invoked when a member joins the Serf cluster.
# Our join script simply adds the node to the load balancer.
cat <<EOF >/tmp/join.sh
if [ "x\${SERF_TAG_ROLE}" != "xlb" ]; then
echo "Not an lb. Ignoring member join."
exit 0
fi
while read line; do
ROLE=\`echo \$line | awk '{print \\\$3 }'\`
if [ "x\${ROLE}" != "xweb" ]; then
continue
fi
echo \$line | \\
awk '{ printf " server %s %s check\\n", \$1, \$2 }' >>/etc/haproxy/haproxy.cfg
done
/etc/init.d/haproxy reload
EOF
sudo mv /tmp/join.sh /usr/local/bin/serf_member_join.sh
chmod +x /usr/local/bin/serf_member_join.sh
# The member leave script is invoked when a member leaves or fails out
# of the serf cluster. Our script removes the node from the load balancer.
cat <<EOF >/tmp/leave.sh
if [ "x\${SERF_TAG_ROLE}" != "xlb" ]; then
echo "Not an lb. Ignoring member leave"
exit 0
fi
while read line; do
NAME=\`echo \$line | awk '{print \\\$1 }'\`
sed -i'' "/\${NAME} /d" /etc/haproxy/haproxy.cfg
done
/etc/init.d/haproxy reload
EOF
sudo mv /tmp/leave.sh /usr/local/bin/serf_member_left.sh
chmod +x /usr/local/bin/serf_member_left.sh
# Configure the agent
cat <<EOF >/tmp/agent.conf
description "Serf agent"
start on runlevel [2345]
stop on runlevel [!2345]
exec /usr/local/bin/serf agent \\
-event-handler "member-join=/usr/local/bin/serf_member_join.sh" \\
-event-handler "member-leave,member-failed=/usr/local/bin/serf_member_left.sh" \\
-event-handler "query:load=uptime" \\
-tag role=${SERF_ROLE} >>/var/log/serf.log 2>&1
EOF
sudo mv /tmp/agent.conf /etc/init/serf.conf
# Start the agent!
sudo start serf
# If we're the web node, then we need to configure the join retry
if [ "x${SERF_ROLE}" != "xweb" ]; then
exit 0
fi
cat <<EOF >/tmp/join.conf
description "Join the serf cluster"
start on runlevel [2345]
stop on runlevel [!2345]
task
respawn
script
sleep 5
exec /usr/local/bin/serf join 10.0.0.5
end script
EOF
sudo mv /tmp/join.conf /etc/init/serf-join.conf
sudo start serf-join
cat <<EOF >/tmp/query.conf
description "Query the serf cluster load"
start on runlevel [2345]
stop on runlevel [!2345]
respawn
script
echo `date` I am "${HOSTNAME}<br>" > /var/www/index.html.1
serf query -no-ack load | sed 's|$|<br>|' >> /var/www/index.html.1
mv /var/www/index.html.1 /var/www/index.html
sleep 10
end script
EOF
sudo mv /tmp/query.conf /etc/init/serf-query.conf
sudo start serf-query
|
