The strategies.yaml parser can incorrectly interpret the YAML elements in the host protocol.

[jrushford]

A user inadvertently created an invalid host definition in the strategies.yaml. When configuring the scheme section of a host the user added the port element as an array field. The parser allowed this but at runtime, the next hop lookup failed to get the proper port number which caused a runtime assertion failure.

Incorrect YAML:

    protocol:
        - scheme: http
        - port:  80

Correct YAML:

    protocol:
        - scheme: http
          port: 80

This is also correct but maybe more clear:

   protocol:
      -
        scheme: http
        port:  80
      -
        scheme: https
        port:  443

The YAML parser should catch and report the error.

[jrushford]

@ywkaras After parsing the YAML, I think a check for all required settings should catch this problem.

[ywkaras]

It seems like we should have seen this note in diags.log:

trafficserver/proxy/http/remap/NextHopSelectionStrategy.cc

Line 76 in 8a948af

NH_Note("Invalid 'scheme' value, '%s', for the strategy named '%s', setting to NH_SCHEME_NONE", scheme_val.c_str(),

Seems like we should either default the scheme to NH_SCHEME_HTTP, or call Emergency() rather than Note(), so TS doesn't continue running in unpredictable ways.

[jrushford]

Fixed by PR #8742