Wait for a server and try to log in via SSH (public key)

wait4server.sh

#!/bin/bash

# global ssh arguments
SSHARG="-o StrictHostKeyChecking=false -o UserKnownHostsFile=/dev/null"
TIMEOUT="$(uname | grep -q Darwin && echo gtimeout || echo timeout)"

# get IP address from hostname
getIP() {
        # return with failure if no server given
        test -z "$1" && return 1

        # query IP
        ip="$(dig +short +search -t a $1 | tail -n 1)"
    test -z "$ip" && ip="$(ping -c1 -W 1000 $1 | egrep -m1 -o "(25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?)\.(25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?)\.(25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?)\.(25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?)")"
        test -z "$ip" \
                && {
                        # check if it is an ip already
                        echo "$1" | egrep "^(25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?)\.(25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?)\.(25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?)\.(25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?)$" -q \
                                && {
                                        # print if its ip
                                        echo "$1"
                                        return 0
                                } \
                                || return 1
                } \
                || {
                        # print queried ip
                        echo "$ip"
                        return 0
                        }

        return 1
}

# ping loop to wait for the server to be booted up
waitforserver() {
        # wait until server is ready to log in via ssh
        ip="$(getIP $1)"
        test -z "$ip" && return 1

        # ping the server
        i=0
        i2=0
        ifail=0
        noloop=""
        # check if server already responds to ping
        $TIMEOUT 1 ping -c1 $ip &> /dev/null \
                && noloop="true"
        # loop through ping
        if [[ "$noloop" != "true" ]]
        then
                while true
                do
                        # timeout config
                        timeoutcmd=1
                        timeoutsuccess=10
                        timeoutfails=300
                        # timeout if server is not pingable
                        # count one up if ping succeeded
                        # reset counter if ping failed
                        $TIMEOUT $timeoutcmd ping -c1 $ip &> /dev/null \
                                && i=$((i+1)) \
                                || i=0

                        # only sleep a second if ping succeeds
                        # otherwise it "sleeps" a second due to timeout command
                        test "$i" -gt 0 && sleep 1 || sleep 0.1
                        # introduce fail count
                        test "$i" = 0 && ifail=$((ifail+1)) || ifail=0

                        # check if minimum of tries reached
                        if [[ "$i" -le $timeoutsuccess ]] && [[ "$ifail" -le $timeoutfails ]]
                        then
                                # if ping does not reach minimum go on and print tries
                                test "$i2" = 0 && printf "\rServer alive for ${i}s (${ifail}s failing).  "
                                test "$i2" = 1 && printf "\rServer alive for ${i}s (${ifail}s failing).. "
                                test "$i2" = 2 && printf "\rServer alive for ${i}s (${ifail}s failing)..."
                                # counter for dots
                                test "$i2" -lt 2 && i2=$((i2+1)) || i2=0
                        elif [[ "$ifail" -ge $timeoutfails ]]
                        then
                                # stop if maximum is reached
                                echo -e "\n${Red}Server not alive (tried for ${ifail}s)."
                                return 1
                        else
                                # stop loop if minimum is reached
                                echo -e "\nServer alive."
                                break
                        fi
                done
        else
                echo "Server alive."
        fi

        # sshing the server
        i=0
        i2=0
        ifail=0
        noloop=""
        # check if server already responds to ping
        ssh -o BatchMode=yes -o ConnectTimeout=1 $SSHARG $ip "echo hello world" &> /dev/null \
                && noloop="true"
        # loop through ping
        if [[ "$noloop" != "true" ]]
        then
                while true
                do
                        # timeout config
                        timeoutcmd=1
                        timeoutsuccess=3
                        timeoutfails=120
                        # timeout if server is not able to log in
                        # count one up if ssh succeeded
                        # reset counter if ssh failed
                        ssh -o BatchMode=yes -o ConnectTimeout=1 $SSHARG $ip "echo hello world" &> /dev/null \
                                && i=$((i+1)) \
                                || i=0

                        # always sleep 1 second
                        sleep 1
                        # introduce fail count
                        test "$i" = 0 && ifail=$((ifail+1)) || ifail=0

                        # check if minimum of tries reached
                        if [[ "$i" -le $timeoutsuccess ]] && [[ "$ifail" -le $timeoutfails ]]
                        then
                                # if ssh does not reach minimum go on and print tries
                                test "$i2" = 0 && printf "\rHost is responding to SSH for $i seconds ($ifail seconds failing).  "
                                test "$i2" = 1 && printf "\rHost is responding to SSH for $i seconds ($ifail seconds failing).. "
                                test "$i2" = 2 && printf "\rHost is responding to SSH for $i seconds ($ifail seconds failing)..."
                                # counter for dots
                                test "$i2" -lt 2 && i2=$((i2+1)) || i2=0
                        elif [[ "$ifail" -ge $timeoutfails ]]
                        then
                                # stop if maximum is reached
                                echo -e "\n${Red}Server is not responding to ssh even after $ifail seconds."
                                return 1
                        else
                                # stop loop if minimum is reached
                                echo -e "\nHost can be logged in."
                                break
                        fi
                done
        else
                echo "Server already responding to SSH login."
                return 0
        fi
}

test -z "$1" && echo "Provide hostname, servername, IP or domain to wait for." || waitforserver $1