Couchbase recover web console password

You will need to have access to the config.dat file that resides onto the couchbase server (can be any of them if is into a cluster).

/opt/couchbase/bin/erl \
-noinput -eval \
'case file:read_file("/opt/couchbase/var/lib/couchbase/config/config.dat") of {ok, B}  -> io:format("~p~n", [binary_to_term(B)]) end.' \
-run init stop | grep cred
  {rest_creds,
         {creds,[{"Administrator",[{password,"Administrator"}]}]}]},

There you go
username : Administrator
password : Administrator