overleaf/services/web/bin/cdn_upload_batch

#!/bin/bash
set -e

content_type=$1
bucket=$2
text_extension=$3
shift 3
content_type_options=""
if [[ "$content_type" != "-" ]]; then
  content_type_options="-h Content-Type:${content_type};charset=utf-8"
fi

# DOCS for gsutil -- it does not have long command line flags!
## global flags
# -h NAME:VALUE   add header, can occur multiples times
# -m              upload with multiple threads
## rsync flags
# -c              use checksums for determining changed files (mtime is not stable)
# -r              traverse into directories recursively
# -x              Python regex for excluding files from the sync
if [[ "$text_extension" == "-" || $(find /tmp/public -type f -name "*$text_extension" | wc -l) != "0" ]]; then
  # Potentially skip upload of non-compressed .js/.css files.
  # shellcheck disable=SC2086
  gsutil \
    -h "Cache-Control:public, max-age=31536000" \
    ${content_type_options} \
    -m \
    rsync \
    -c \
    -r \
    "$@" \
    "/tmp/public/" \
    "${bucket}/public/"
fi

# shellcheck disable=SC2086
gsutil \
  -h "Cache-Control:public, max-age=31536000" \
  -h "Content-Encoding:gzip" \
  ${content_type_options} \
  -m \
  rsync \
  -c \
  -r \
  "$@" \
  "/tmp/compressed/public/" \
  "${bucket}/public/"