BASH script: exponential backoff with limit of 60s

exponential-backoff-with-limit.bash

set -E # required to get exit code from while ()
BASE=${BACKOFF_BASE:-1}
MAX=${BACKOFF_MAX:-60}
FAILURES=0
while (

  # Code here
  
) 2>&1; RC=$?; [[ $RC -ne 0 ]]; do
  FAILURES=$(( $FAILURES + 1 ))
  SECONDS=$(( ($BASE * 2) ** ($FAILURES - 1) ))
  if [[ $SECONDS -ge $MAX ]]; then
    SECONDS=$MAX
    FAILURES=$(( $FAILURES - 1 )) # make sure SECONDS doesn't grow too large
  fi
  print_warning "$FAILURES failure(s), retrying in $SECONDS second(s)" >&2
  sleep $SECONDS
  echo
done