punktfunk/scripts/ci/retry.sh

# shellcheck shell=bash
# Run a command, retrying with linear backoff:  bash scripts/ci/retry.sh <attempts> <cmd> [args…]
#
# WHY THIS EXISTS: the runner box executes many jobs in parallel and its network drops
# packets under that load — observed as instant "[6] Could not resolve hostname" from
# flatpak/curl (dropped UDP DNS) and "dial tcp: i/o timeout" from the deploy steps
# (dropped TCP SYNs to unom-1), each seconds after other network calls in the same job
# succeeded. Tools with built-in mirror retries (dnf) ride it out; single-shot fetches
# (flatpak remote-add, rsync, ssh) killed the whole heavy flatpak build on one dropped
# packet. Wrap every single-shot network command in CI with this instead.
#
# Backoff is attempt*10s (10/20/30/…), so 5 attempts spread over ~1.5 min — long enough
# to outlive a load burst, short enough not to eat the job timeout. The wrapped command's
# stdout passes through untouched (safe for $(…) capture); retry chatter goes to stderr.
set -u

attempts="$1"; shift
rc=1
for i in $(seq 1 "$attempts"); do
  "$@" && exit 0
  rc=$?
  [ "$i" -eq "$attempts" ] && break
  echo "::warning::attempt $i/$attempts failed (rc=$rc): $* — retrying in $((i * 10))s" >&2
  sleep $((i * 10))
done
echo "::error::all $attempts attempts failed (rc=$rc): $*" >&2
exit "$rc"