Automate fetching lists of new Fastly IPs

[ewdurbin]

#290 updated the firewall for the cdn-logs host with the current ranges of Fastly IP addresses fetched via the API at https://developer.fastly.com/reference/api/utils/public-ip-list/

We should add a mechanism to automatically keep this list up to date so we don't cause logs to stop flowing again. Whatever range was being used to send syslog streams changed sometime in may and it was missed causing fastly to stop reporting any logs at all.

[egeakman]

@ewdurbin did you skip the letter "r" on purpose between "q" and "s" here:

psf-salt/pillar/base/firewall/fastly-logging.sls

Lines 51 to 56 in d6c01b1

	fastly_syslog_ipv4_q:
	source: 185.31.16.0/22
	port: 514
	fastly_syslog_ipv4_s:
	source: 199.27.72.0/21
	port: 514

[ewdurbin]

@egeakman good catch :) I manually typed... so I guess I just skipped r :)

[ewdurbin]

Resolved via #295