A bash script for health checking a URL. See the start of the script for instructions in how to run it.

health_checking.sh

#!/usr/bin/env bash

# How to run:
# 1) chmod +x health_checking.sh
# 2) ./health_checking.sh --url=http://localhost:8000 --timeout=60

# Define a timestamp function
timestamp() {
    date +"%s"
}

# Define a date function
dateString() {
    date +"%T"
}

startTs=$(timestamp)
echo "started at $(dateString) ($(timestamp))"

for i in "$@"
do
case ${i} in
    --url=*)
    url="${i#*=}"
    ;;
    --timeout=*)
    timeout="${i#*=}"
    ;;
    --body=*)
    body="${i#*=}"
    ;;
    --method=*)
    method="${i#*=}"
    ;;
    *)
    echo "Unknown option ${i}"
    echo "Ended at $(dateString) ($(timestamp)) (duration: $(($(timestamp)-${startTs})) seconds)"
    exit -1
    ;;
esac
done

if [[ -z "${url}" ]]; then
echo "url is missing, set it as environment variable or pass it as argument ('./health_checking.sh --url=http://localhost:8000 --method=GET --body='{\"id\": 1}' --timeout=60' or 'export url=http://localhost:8000')"
echo "Ended at $(dateString) ($(timestamp)) (duration: $(($(timestamp)-${startTs})) seconds)"
exit -1
fi

if [[ -z "${body}" ]]; then
body=''
echo "body is missing, using empty body. You can set it as environment variable or pass it as argument ('./health_checking.sh --url=http://localhost:8000 --method=GET --body='{\"id\": 1}' --timeout=60' or export body='{\"id\": 1}')"
fi

if [[ -z "${method}" ]]; then
method="GET"
echo "method is missing, using default '${method}'. You can set it as environment variable or pass it as argument ('./health_checking.sh --url=http://localhost:8000 --method=GET --body='{\"id\": 1}' --timeout=60' or 'export method=${method}')"
fi

if [[ -z "${timeout}" ]]; then
timeout=60
echo "timeout is missing, using default '${timeout}' seconds. You can set it as environment variable or pass it as argument ('./health_checking.sh --url=http://localhost:8000 --method=GET --body='{\"id\": 1}' --timeout=60' or 'export timeout=${timeout}')"
fi

echo "Health checking for url: '${url}', with timeout: '${timeout}' seconds."

response="0"
sleepTime=0  # do not sleep the first time we call the url

while [[ ${response} -ne "200" ]]
do

    # check if we exceeded the timeout
    totalTimeSpent=$(($(timestamp)-${startTs}))
    if [[ "$totalTimeSpent" -ge "$timeout" ]]; then
    echo "Timeout Error! Didn't receive a success in ${timeout} seconds."
    exit -1
    fi

    sleep ${sleepTime}
    sleepTime=1  # before calling the url next time sleep for 1 second

    if [[ -z "${body}" ]]; then
    response=$(curl -X ${method} --write-out "%{http_code}\n" --silent --output /dev/null "$url")
    else
    response=$(curl -X ${method} -d "${body}" --write-out "%{http_code}\n" --silent --output /dev/null "$url")
    fi
    echo "Response waiting for '200', got: '$response'"
done