OS X Server does not create the xcsbuildd.plist file and usually fails with this error:
SSH Known Hosts file path is located at /Library/Server/Xcode/Config/ssh_known_hosts SSH strict host checking is enabled (you can disable this by editing the SSHStrictHostKeyChecking key in /Library/Server/Xcode/Config/xcsbuildd.plist Untrusted HTTPS certificates is disabled (you can enable this by editing the TrustSelfSignedSSLCertificates key in /Library/Server/Xcode/Config/xcsbuildd.plist
Here is a file if you need it: xcsbuildd.plist
Simply copy it to
/Library/Server/Xcode/Config/ folder and then restart xcsbuildd with
sudo killall xcsbuildd.