You're right.  So the options so far:
1.  Use a new convention that requires the needed appender first in the logback config
2.  Use a new convention that says the needed appender must have a certain name ("A1"?)
3.  Add a config that stores the name of the needed appender, and make sure that appender has the same name.

If we had reasonable defaults, option 3 does not seem so bad.  A reasonable default would be "A1," so even current installations would not need to change anything to have logs and the logviewer continue to work.

In theory, (following your suggestion) someone may want to launch different logviewers to read different logs.  In that case, there could be a common logback config with different appenders, and each logviewer would need its own appender to look for.  Option 3 could also support this use case.  (E.g., a logviewer for "METRICS" only) This is a use case that makes it necessary instead of redundant to configure the appender name in both the storm and logback configs.