This is the "certificate downloader" app that runs in the container
with haproxy (via haproxy's "program" configuration).

This version fixes a bug in which the downloader did not always delete
the PEM file for a deleted Secret.

The Ingress is updated by changing to a Secret with a different name.

When an Ingress is changed (same name with modified configuration)
so that Secret for TLS is changed (another Secret with a different
name), the PEM file for the first Secret is not removed from the
haproxy configuration directory.

Optionally support a parameter object to control internal service shards

See merge request uplex/varnish/k8s-ingress!8

k8s uses re2, which does not support lookaround, so this rather
complicated pattern is what I came up with to forbid vcl and
vk8s prefixes.

The shard director supports many interesting use cases, for example

- retrying backend requests on different backends

- sharding by custom keys, for example for "client stickyness"
  or cache optimization

This patch adds the option to create parameter objects for backends
using the shard director.

Each named parameter object will be created only once and associated
with all directors for which the backend configuration names them.

Sleep a few seconds longer before grepping the controller log.
During a lengthy e2e test, the expected log line was not found
by grep in time.

The default format has been changed to include the instance name
and the test only needs to check for a sensible Via header at all.

... a COPYING file exists.