docker-entrypoint.sh

#!/usr/bin/env bash
set -e

# Enable core dumps. Requires privileged mode.
if [[ "${RELAY_ENABLE_COREDUMPS:-}" == "1" ]]; then
  mkdir -p /var/dumps
  chmod a+rwx /var/dumps
  echo '/var/dumps/core.%h.%e.%t' > /proc/sys/kernel/core_pattern
  ulimit -c unlimited
fi

# Sleep for the specified number of seconds before starting.
# For example, can be helpful to synchronize container startup in Kubernetes environment.
if [[ -n "${RELAY_DELAY_STARTUP_SECONDS:-}" ]]; then
  echo "Sleeping for ${RELAY_DELAY_STARTUP_SECONDS}s..."
  sleep "${RELAY_DELAY_STARTUP_SECONDS}"
fi

# Make sure that a specified URL (e.g. the upstream or a proxy sidecar) is reachable before starting.
# Only 200 response is accepted as success.
if [[ -n "${RELAY_PRESTART_ENDPOINT:-}" ]]; then
  max_retry="${RELAY_PRESTART_MAX_RETRIES:-120}"
  curl_timeout="${RELAY_PRESTART_REQUEST_TIMEOUT:-1}"
  for attempt in $(seq 0 "${max_retry}"); do
    if [[ "${attempt}" == "${max_retry}" ]]; then
      echo "The prestart endpoint has not returned 200 after ${max_retry} attempts, exiting!"
      exit 1
    fi
    status=$(curl --max-time "${curl_timeout}" --show-error --silent \
                  --output /dev/null --write-out "%{http_code}" \
                  -H 'Connection: close' \
                  "${RELAY_PRESTART_ENDPOINT}" \
              || true)
    if [[ "${status}" == "200" ]]; then
      break
    fi
    echo "Waiting for a 200 response from ${RELAY_PRESTART_ENDPOINT}, got ${status}"
    sleep 1
  done
fi

# For compatibility with older images
if [ "$1" == "bash" ]; then
  set -- bash "${@:2}"
elif [ "$(id -u)" == "0" ]; then
  set -- gosu relay /bin/relay "$@"
else
  set -- /bin/relay "$@"
fi

exec "$@"