Update Dockerfile curl calls to use new URL and fail safer

[john-coleman]

Fixes https://github.com/zalando-stups/planb-cassandra/issues/243

• Previous https://www.apache.org/dist/cassandra/KEYS URL is a 302 redirect that is not being follows by curl
• This was causing errors from apt-key such as:
  • Warning: apt-key output should not be parsed (stdout is not a terminal)
  • gpg: no valid OpenPGP data found.

[a1exsh]

The current version of the download instructions page says use https://downloads.apache.org/cassandra/KEYS: https://cassandra.apache.org/download/

curl -I https://downloads.apache.org/cassandra/KEYS
HTTP/1.1 200 OK
Date: Tue, 07 Jul 2020 10:28:34 GMT
Server: Apache
Last-Modified: Thu, 26 Mar 2020 18:13:43 GMT
ETag: "3f242-5a1c5f1f8fdfe"
Accept-Ranges: bytes
Content-Length: 258626
Access-Control-Allow-Origin: *

Doesn't need a redirect. Let's use this one?

[a1exsh]

@john-coleman thanks. Can we drop the follow redirect flags? Doesn't leave me with a good warm feeling when downloading signature keys.

[john-coleman]

sure

[a1exsh]

:+1:

[john-coleman]

👍

[slitsche]

:+1: