MINOR: global: generate random cluster.secret if not defined

If no cluster-secret is defined by the user, a random one is silently
generated.

This ensures that at least QUIC Retry tokens are generated if abnormal
conditions are detected. However, it is advisable to specify it in the
configuration for tokens to be valid even after a reload or across LBs
instances in the same cluster.

This should be backported up to 2.6.
3 files changed