We need to replace a haproxy setup with apache. That is somehow strait forward but the puppetlabs-apache-module has a bug that prevents to do it.
The problem is, that the balancer config gets created on server config level and not in vhost level. So the out-of-band checks by proxy_hcheck are done on that level too.
By using https backends you see the following errors in log:
The hint is a good hint but does not help as it is not possible to enable SSLProxyEngine on server level.
The solution is to put that balancer config inside the vhost but this is not supported by the module.