wait-for-it.sh

#!/usr/bin/env bash
#   Use this script to test if a given TCP host/port are available
#
# The MIT License (MIT)
# Copyright (c) 2016 Giles Hall
#
# Permission is hereby granted, free of charge, to any person obtaining a copy of
# this software and associated documentation files (the "Software"), to deal in
# the Software without restriction, including without limitation the rights to
# use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies
# of the Software, and to permit persons to whom the Software is furnished to do
# so, subject to the following conditions:
#
# The above copyright notice and this permission notice shall be included in all
# copies or substantial portions of the Software.
#
# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
# IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
# FITNESS FOR A PARTICULAR PURPOSE AND NON-INFRINGEMENT. IN NO EVENT SHALL THE
# AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
# LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
# OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
# SOFTWARE.
#
cmdname=$(basename $0)

echoerr() { if [[ ${QUIET} -ne 1 ]]; then echo "$@" 1>&2; fi }

usage()
{
    cat << USAGE >&2
Usage:
    ${cmdname} host:port [-s] [-t timeout]
    -h HOST | --host=HOST       Host or IP under test
    -p PORT | --port=PORT       TCP port under test
                                Alternatively, you specify the host and port as host:port
    -s | --strict               Only execute sub-command if the test succeeds
    -q | --quiet                Don't output any status messages
    -t TIMEOUT | --timeout=TIMEOUT
                                Timeout in seconds, zero for no timeout
USAGE
    exit 1
}

wait_for()
{
    if [[ ${TIMEOUT} -gt 0 ]]; then
        echoerr "$cmdname: waiting $TIMEOUT seconds for $HOST:$PORT"
    else
        echoerr "$cmdname: waiting for $HOST:$PORT without a timeout"
    fi
    start_ts=$(date +%s)
    while :
    do
        if [[ ${ISBUSY} -eq 1 ]]; then
            nc -z ${HOST} ${PORT}
            result=$?
        else
            (echo > /dev/tcp/${HOST}/${PORT}) >/dev/null 2>&1
            result=$?
        fi
        if [[ ${result} -eq 0 ]]; then
            end_ts=$(date +%s)
            echoerr "$cmdname: $HOST:$PORT is available after $((end_ts - start_ts)) seconds"
            break
        fi
        sleep 1
    done
    return ${result}
}

wait_for_wrapper()
{
    # In order to support SIGINT during timeout: http://unix.stackexchange.com/a/57692
    if [[ ${QUIET} -eq 1 ]]; then
        timeout ${BUSYTIMEFLAG} ${TIMEOUT} $0 --quiet --child --host=${HOST} --port=${PORT} --timeout=${TIMEOUT} &
    else
        timeout ${BUSYTIMEFLAG} ${TIMEOUT} $0 --child --host=${HOST} --port=${PORT} --timeout=${TIMEOUT} &
    fi
    PID=$!
    trap "kill -INT -${PID}" INT
    wait ${PID}
    RESULT=$?
    if [[ ${RESULT} -ne 0 ]]; then
        echoerr "$cmdname: timeout occurred after waiting $TIMEOUT seconds for $HOST:$PORT"
    fi
    return ${RESULT}
}

# process arguments
while [[ $# -gt 0 ]]
do
    case "$1" in
        *:* )
            hostport=(${1//:/ })
            HOST=${hostport[0]}
            PORT=${hostport[1]}
            shift 1
            ;;
        --child)
            CHILD=1
            shift 1
            ;;
            -q | --quiet)
            QUIET=1
            shift 1
            ;;
        -s | --strict)
            STRICT=1
            shift 1
            ;;
        -h)
            HOST="$2"
            if [[ ${HOST} == "" ]]; then break; fi
            shift 2
            ;;
        --host=*)
            HOST="${1#*=}"
            shift 1
            ;;
        -p)
            PORT="$2"
            if [[ ${PORT} == "" ]]; then break; fi
            shift 2
            ;;
        --port=*)
            PORT="${1#*=}"
            shift 1
            ;;
        -t)
            TIMEOUT="$2"
            if [[ ${TIMEOUT} == "" ]]; then break; fi
            shift 2
            ;;
        --timeout=*)
            TIMEOUT="${1#*=}"
            shift 1
            ;;
        --help)
            usage
            ;;
        *)
            echoerr "Unknown argument: $1"
            usage
            ;;
    esac
done

if [[ "$HOST" == "" || "$PORT" == "" ]]; then
    echoerr "Error: you need to provide a host and port to test."
    usage
fi

TIMEOUT=${TIMEOUT:-15}
STRICT=${STRICT:-0}
CHILD=${CHILD:-0}
QUIET=${QUIET:-0}

# check to see if timeout is from busybox?
# check to see if timeout is from busybox?
TIMEOUT_PATH=$(realpath $(which timeout))
if [[ ${TIMEOUT_PATH} =~ "busybox" ]]; then
        ISBUSY=1
        BUSYTIMEFLAG="-t"
else
        ISBUSY=0
        BUSYTIMEFLAG=""
fi

if [[ ${CHILD} -gt 0 ]]; then
    wait_for
    RESULT=$?
    exit ${RESULT}
else
    if [[ ${TIMEOUT} -gt 0 ]]; then
        wait_for_wrapper
        RESULT=$?
    else
        wait_for
        RESULT=$?
    fi
fi

exit ${RESULT}