I'm having trouble with one of our HAProxy-Servers that uses a backend with TLS. When starting HAProxy the backend will report all servers as down:
Server web_remote/apache_rem_1 is DOWN, reason: Layer6 invalid response, info: "SSL handshake failure", check duration: 41ms. 1 active and 0 backup servers left. 0 sessions active, 0 requeued, 0 remaining in queue.
The configuration for the backend is as follows:
backend web_remote balance leastconn option httpchk HEAD / option redispatch retries 3 default-server inter 5000 rise 2 fall 5 maxconn 10000 maxqueue 50000 server apache_rem_1 192.0.2.1:12345 check maxconn 1000 maxqueue 5000 ssl ca-file /etc/ssl/web.pem server apache_rem_2 2001:DB8:3:4:5:6:8:12345 check maxconn 1000 maxqueue 5000 ssl ca-file /etc/ssl/web.pem
This backend worked just fine until now, a quick
wget on the server also worked and
openssl s_client reports the certificate of the backend to be valid.
Is there anything else for HAProxy/TLS that could be configured wrong? How could I debug this issue when everything else reports the handshake was successful?