log.With does not compose well with log.Levels #63
Description
Context
I would like the ability to do something like this:
var Log log.Logger
func HandleTask(taskID int) error {
logger := log.With(Log, "task", taskID)
logger.Info("event", "start")
...
logger.Debug("event", "query", "query", query)
if err := doQuery(query); err != nil {
logger.Error("event", "query", "err", err)
return err
}
...
logger.Info("event", "done")
}The important aspect of my example is the re-use of logging context across multiple severity levels.
The problem
As it stands now, package log encourages us to implement log levels via multiple Loggers each with a different level context created by a call to log.With. Unfortunately this approach makes it cumbersome to create additional contextual loggers on top of the leveled loggers. For example:
var lvls = log.NewLevels()
func HandleTask(taskID int) error {
dlog := log.With(lvls.Debug, "task", taskID)
ilog := log.With(lvls.Info, "task", taskID)
elog := log.With(lvls.Error, "task", taskID)
ilog.Log("event", "start")
...
dlog.Log("event", "query", "query", query)
if err := doQuery(query); err != nil {
elog.Log("event", "query", "err", err)
return err
}
...
ilog.Log("event", "done")
}In addition to being cumbersome, each call to log.With costs allocations.
Challenge
Can we find a good way to avoid the need for multiple calls to log.With when doing leveled logging?