backoff.sh

#!/bin/bash

set -uo pipefail

function check_s3_status() {
    S3_BUCKET_STATUS=$(curl -I https://my-buckets.s3.amazonaws.com | head -n 1)
    [[ ${S3_BUCKET_STATUS} == *"HTTP/1.1 200 OK"* ]] && echo "OK with code: ${S3_BUCKET_STATUS}" && return 0
    echo "Failed with code: ${S3_BUCKET_STATUS}"
    return 1
}

function with_backoff {
  local MAX_RETRIES=6
  local DELAY=0
  local RETRY_COUNT=0
  local EXIT_CODE=0

  while [[ "${MAX_RETRIES}" -gt "${RETRY_COUNT}" ]]
  do
    "$@"
    EXIT_CODE=$?

    if [[ ${EXIT_CODE} == 0 ]]
    then
      break
    fi

    echo "Retrying in ${DELAY}"
    sleep ${DELAY}
    RETRY_COUNT=$(( ${RETRY_COUNT} + 1 ))
    DELAY=$(( (2**${RETRY_COUNT}) * 5 ))
  done

  return ${EXIT_CODE}
}

with_backoff check_s3_status