caddy-frontend: support failover backend.
TODO:
- really implement (Luke)
-
drop
health-check-failover-path
, but keep the query string like?a=b&p=
for configuredurl
,https-url
.health-check-failover-url
andhealth-check-failover-https-url
- test (add, adapt) (Luke)
- fix post testing (Luke)
- do manual checks on some clusters
/cc @luke @vpelletier