Serf event handler for nginx loadbalancing with multiple apps

eventhandler.sh

#!/usr/bin/env bash
#This script will get executed each time a event happens
#on the serf cluster
if [ ${SERF_EVENT} = "member-join" ]; then
    #We will go over each line that is returned to us from serf
    while read line; do
        #Lets assign some variables

        #First we shall get the nodename
        nodename=`echo $line | awk '{print \$1 }'`

        #Next the IP
        ip=`echo $line | awk '{print \$2 }'`

        #Then the tag1
        tag1=`echo $line | awk '{print \$4 }' |cut -d "," -f "1"`
        #Tag2
        tag2=`echo $line | awk '{print \$4 }' |cut -d "," -f "2"`

        # I'll assign this as a dict, so that i can reference it directly (serf doesnt give the tags in same order each time)
        declare -A tags
        tags=( [`echo $tag1 |cut -d "=" -f 1`]=`echo $tag1 |cut -d "=" -f 2` [`echo $tag2 |cut -d "=" -f 1`]=`echo $tag2 |cut -d "=" -f 2` )

        #If its a new LB that joined (This is if its nginx that are joining itself into the cluster)
        #The reason behind having this, is that if the docker container crashed
        #We want to be able to spawn a new one in its place, which will find the nodes already active and bring them up
        if [ ${tags[role]} = "lb" ]; then
            #Executing the serf members to find the active members
            serf members |grep webserver |grep alive | while read line; do
                #Getting the IP
                ip=`echo $line |cut -d " " -f 2 |cut -d ":" -f 1`
                #Getting tags and setting as dict
                tag1=`echo $line | awk '{print \$4 }' |cut -d "," -f "1"`
                tag2=`echo $line | awk '{print \$4 }' |cut -d "," -f "2"`
                declare -A tags
                tags=( [`echo $tag1 |cut -d "=" -f 1`]=`echo $tag1 |cut -d "=" -f 2` [`echo $tag2 |cut -d "=" -f 1`]=`echo $tag2 |cut -d "=" -f 2` )

                #At this point if its a app1 server we add it to app1
                if [ ${tags[app]} = "app1" ]; then
                    sed -i 's/upstream app1 {/upstream app1 {\n \t\tserver '$ip';/' /etc/nginx/nginx.conf
                    /etc/init.d/nginx reload
                fi
                #At this point if its a app1 server we add it to app2
                if [ ${tags[app]} = "app2" ]; then
                    echo "updating conf" >> log.txt
                    sed -i 's/upstream app2 {/upstream app2 {\n \t\tserver '$ip';/' /etc/nginx/nginx.conf
                    /etc/init.d/nginx reload
                fi
            done
        fi
        #If its a new webserver that joined
        if [ ${tags[role]} = "webserver" ]; then
            if [ ${tags[app]} = "app1" ]; then
                sed -i 's/upstream app1 {/upstream app1 {\n \t\tserver '$ip';/' /etc/nginx/nginx.conf
                /etc/init.d/nginx reload
                fi
            if [ ${tags[app]} = "app2" ]; then
                echo "updating conf" >> log.txt
                sed -i 's/upstream app2 {/upstream app2 {\n \t\tserver '$ip';/' /etc/nginx/nginx.conf
                /etc/init.d/nginx reload
                fi
        fi
    done

#Update procedure
#This is used as a failsafe, if for some reason a member isnt joined correctly first time
#We can trigger this custom event at a random basis, which will ensure that we manually refresh based on membership status
elif [ ${SERF_EVENT} = "user" ]; then
    if [ ${SERF_USER_EVENT} = "refreshConfig" ]; then
        serf members |grep webserver |grep alive | while read line; do
            #Getting the IP
            ip=`echo $line |cut -d " " -f 2 |cut -d ":" -f 1`
            #First ill remove IP
            sed -i '/server '$ip';/d' /etc/nginx/nginx.conf
            #Getting tags and setting as dict
            tag1=`echo $line | awk '{print \$4 }' |cut -d "," -f "1"`
            tag2=`echo $line | awk '{print \$4 }' |cut -d "," -f "2"`
            declare -A tags
            tags=( [`echo $tag1 |cut -d "=" -f 1`]=`echo $tag1 |cut -d "=" -f 2` [`echo $tag2 |cut -d "=" -f 1`]=`echo $tag2 |cut -d "=" -f 2` )

            #At this point if its a app1 server we add it to app1
            if [ ${tags[app]} = "app1" ]; then
                sed -i 's/upstream app1 {/upstream app1 {\n \t\tserver '$ip';/' /etc/nginx/nginx.conf
            fi
            #At this point if its a app1 server we add it to app2
            if [ ${tags[app]} = "app2" ]; then
                echo "updating conf" >> log.txt
                sed -i 's/upstream app2 {/upstream app2 {\n \t\tserver '$ip';/' /etc/nginx/nginx.conf
            fi
        done
        /etc/init.d/nginx reload
    fi

#if a member leaves gracefully
elif [ ${SERF_EVENT} = "member-leave" ]; then
    while read line; do
        #Lets assign some variables
        nodename=`echo $line | awk '{print \$1 }'`
        ip=`echo $line | awk '{print \$2 }'`
        tag1=`echo $line | awk '{print \$4 }' |cut -d "," -f "1"`
        tag2=`echo $line | awk '{print \$4 }' |cut -d "," -f "2"`
        declare -A tags
        tags=( [`echo $tag1 |cut -d "=" -f 1`]=`echo $tag1 |cut -d "=" -f 2` [`echo $tag2 |cut -d "=" -f 1`]=`echo $tag2 |cut -d "=" -f 2` )
        sed -i '/server '$ip';/d' /etc/nginx/nginx.conf
        /etc/init.d/nginx reload
    done

#if a member leaves by failing (eg crashing, network issue and so on)
elif [ ${SERF_EVENT} = "member-failed" ]; then
    while read line; do
        #Lets assign some variables
        nodename=`echo $line | awk '{print \$1 }'`
        ip=`echo $line | awk '{print \$2 }'`
        tag1=`echo $line | awk '{print \$4 }' |cut -d "," -f "1"`
        tag2=`echo $line | awk '{print \$4 }' |cut -d "," -f "2"`
        declare -A tags
        tags=( [`echo $tag1 |cut -d "=" -f 1`]=`echo $tag1 |cut -d "=" -f 2` [`echo $tag2 |cut -d "=" -f 1`]=`echo $tag2 |cut -d "=" -f 2` )
        sed -i '/server '$ip';/d' /etc/nginx/nginx.conf
        /etc/init.d/nginx reload
    done
fi