download.sh

#!/usr/bin/env bash
#
# Licensed to the Apache Software Foundation (ASF) under one or more
# contributor license agreements.  See the NOTICE file distributed with
# this work for additional information regarding copyright ownership.
# The ASF licenses this file to You under the Apache License, Version 2.0
# (the "License"); you may not use this file except in compliance with
# the License.  You may obtain a copy of the License at
#
#     http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.

set -euo pipefail

APACHE_DIST_URLS=(
  "https://www.apache.org/dyn/closer.cgi?action=download&filename="
  # if the version is outdated (or we're grabbing the .asc file), we might have to pull from the dist/archive :/
  "https://www-us.apache.org/dist/"
  "https://www.apache.org/dist/"
  "https://archive.apache.org/dist/"
)

download() {
  local f="$1"; shift
  local distFile="$1"; shift
  local success=
  local distUrl=
  for distUrl in "${APACHE_DIST_URLS[@]}"; do
    echo "Attempting to fetch $f from $distUrl$distFile"
    if wget -nv -O "$f" "$distUrl$distFile"; then
      success=1
      break
    fi
  done
  [ -n "$success" ]
}

existing_file=$1
download_file=$2
dist_file=$3

if [[ "$existing_file" == "_NOT_SET" ]]; then
  download "$download_file" "$dist_file"
else
  [ -f "/tmp/$existing_file" ] || { echo "Existing file $existing_file does not exist"; exit 1; }
  echo "Skipping download of $existing_file"
  mv "/tmp/$existing_file" "$download_file"
fi