[jira] [Resolved] (COUCHDB-2970) config:set("log","level",...) fails to change lager backend levels

["Alexander Shorin (JIRA)" <ji...@apache.org>]

     [ https://issues.apache.org/jira/browse/COUCHDB-2970?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Alexander Shorin resolved COUCHDB-2970.
---------------------------------------
       Resolution: Fixed
         Assignee: Jay Doane
    Fix Version/s: 2.0.0

> config:set("log","level",...) fails to change lager backend levels
> ------------------------------------------------------------------
>
>                 Key: COUCHDB-2970
>                 URL: https://issues.apache.org/jira/browse/COUCHDB-2970
>             Project: CouchDB
>          Issue Type: Bug
>          Components: Logging
>            Reporter: Jay Doane
>            Assignee: Jay Doane
>             Fix For: 2.0.0
>
>
> The following remsh session shows that at first, both config log level and lager_file_backend levels are the same (info), but after we use config to change the level to notice, the lager level remains at info:
> {code}
> (cloudant@db1.v)26> config:get("log","level").
> "info"
> (cloudant@db1.v)27> gen_event:which_handlers(lager_event).
> [{lager_file_backend,"/var/log/cloudant/cloudant.log"},
>  lager_backend_throttle]
> (cloudant@db1.v)28> lager:get_loglevel({lager_file_backend,"/var/log/cloudant/cloudant.log"}).
> info
> (cloudant@db1.v)29> config:set("log","level","notice",false).
> ok
> (cloudant@db1.v)30> lager:get_loglevel({lager_file_backend,"/var/log/cloudant/cloudant.log"}).
> info
> {code}
> The problem occurs because https://github.com/apache/couchdb-couch-log-lager/blob/master/src/couch_log_lager.erl#L67 obtains the handlers from application:get_env(lager, handlers), which returns the a structure defined in sys.config, but it should use gen_event:which_handlers(lager_event), which returns the actual list of handlers:
> {code}
> (cloudant@db1.v)31> application:get_env(lager, handlers).                                
> {ok,[{lager_file_backend,
>          [{file,"/var/log/cloudant/cloudant.log"},
>           {formatter,lager_default_formatter},
>           {formatter_config,
>               [date," ",time," [",severity,"] ",node," ",pid," ",message,
>                "\n"]}]}]}
> (cloudant@db1.v)32> gen_event:which_handlers(lager_event).                               [{lager_file_backend,"/var/log/cloudant/cloudant.log"},
>  lager_backend_throttle]
> {code}



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