cloudflared falls back aggressively to HTTP/2 protocol if a connection
attempt with QUIC failed. This was done to ensure that machines with UDP
egress disabled did not stop clients from connecting to the cloudlfare
edge. This PR improves on that experience by having cloudflared remember
if a QUIC connection was successful which implies UDP egress works. In
this case, cloudflared does not fallback to HTTP/2 and keeps trying to
connect to the edge with QUIC.
Connections from cloudflared to Cloudflare edge are long lived and may
break over time. That is expected for many reasons (ranging from network
conditions to operations within Cloudflare edge). Hence, logging that as
Error feels too strong and leads to users being concerned that something
is failing when it is actually expected.
With this change, we wrap logging about connection issues to be aware
of the tunnel state:
- if the tunnel has no connections active, we log as error
- otherwise we log as warning
Sudarsan Reddy
Nuno Diegues