ATS Should Fail to Start if sni.yaml Fails to Load

[rob05c]

Starting ATS with a malformed sni.yaml in ATS 9.1 results in:

[Jul 30 19:24:30.069] traffic_server ERROR: <SSLSNIConfig.cc:172 (Initialize)> /opt/trafficserver/etc/trafficserver/sni.yaml failed to load: 1 [1]: yaml-cpp: error at line 1889, column 25: unknown value "STRICT"

But ATS still starts, just without loading or applying anything in sni.yaml.

This can be a security issue. If a user has records.config configured to allow everything, and uses sni.yaml to block or allow each FQDN, this will result in everything being allowed. And a user could easily miss the above log message.

It sounds like we probably want ATS to load anyway if sni.yaml doesn't exist.

But if it exists and is malformed, either with invalid YAML or with data errors (such as bad enums, as above), I think ATS should fail to start, for security.

[rob05c]

@shinrich ^