Available variables to be used in the log formatter functions, eg in layout_glue_generator:

  • levelr: log level as an R object, eg INFO

  • level: log level as a string, eg INFO

  • time: current time as POSIXct

  • node: name by which the machine is known on the network as reported by Sys.info

  • arch: machine type, typically the CPU architecture

  • os_name: Operating System's name

  • os_release: Operating System's release

  • os_version: Operating System's version

  • user: name of the real user id as reported by Sys.info

  • pid: the process identification number of the R session

  • node: name by which the machine is known on the network as reported by Sys.info

  • r_version: R's major and minor version as a string

  • ns: namespace usually defaults to global or the name of the holding R package of the calling the logging function

  • ns_pkg_version: the version of ns when it's a package

  • ans: same as ns if there's a defined logger for the namespace, otherwise a fallback namespace (eg usually global)

  • topenv: the name of the top environment from which the parent call was called (eg R package name or GlobalEnv)

  • call: parent call (if any) calling the logging function

  • fn: function's (if any) name calling the logging function

  log_level = NULL,
  namespace = NA_character_,
  .logcall = sys.call(),
  .topcall = sys.call(-1),
  .topenv = parent.frame()



log level as per log_levels


string referring to the logger environment / config to be used to override the target of the message record to be used instead of the default namespace, which is defined by the R package name from which the logger was called, and falls back to a common, global namespace.


the logging call being evaluated (useful in formatters and layouts when you want to have access to the raw, unevaluated R expression)


R expression from which the logging function was called (useful in formatters and layouts to extract the calling function's name or arguments)


original frame of the .topcall calling function where the formatter function will be evaluated and that is used to look up the namespace as well via logger:::top_env_name