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