logger

Levels

The following table defines the log levels and messages in logger, in decreasing order of severity. The left column lists the log level designation in and the right column provides a brief description of each log level.

Level	Description
Fatal	Severe errors that cause premature termination.
	Expect these to be immediately visible on a status console.
Error	Other runtime errors or unexpected conditions.
	Expect these to be immediately visible on a status console.
Critical
Warn	Use of deprecated APIs, poor use of APIConfig, 'almost' errors, other runtime situations that are undesirable or unexpected, but not necessarily "wrong".
	Expect these to be immediately visible on a status console.
Info	Interesting runtime events (startup/shutdown).
	Expect these to be immediately visible on a console, so be conservative and keep to a minimum.
Debug	Detailed information on the flow through the system.
	Expect these to be written to logs only.
Trace	Most detailed information.
	Expect these to be written to logs only.

Colors

The supported keys in the :colors keyword list are:

Level	Color
Fatal	Defaults to: Red
Error	Defaults to: Red
Critical	Defaults to: LightRed
Warn	Defaults to: Yellow
Info	Defaults to: Green
Debug	Defaults to: Blue
Trace	Defaults to: Magenta

See the IO.ANSI module for a list of colors and attributes.

For example, info takes precedence over debug. If your log level is set to info, info, warn, and error will be printed to the console. If your log level is set to warn, only warn and error will be printed.

Types

Type	Format
Text	%[levelName]s:%[name]s:%[message]s%[fields]s\n
Apache Common	{host} {userIdentifier} {authUserId} [{datetime}] "{method} {request} HTTP/1.0" {responseCode} {bytes}
Apache Combined	%[host]s - %[user]s %[authUserId]d [%[ASC_TIME]s] "%[method]s %[request]s HTTP/1.0" %[responseCode]d %[bytes]d "%[referrer]s" "%[agent]s"
Apache Error	[{timestamp}] [{module}:{severity}] [pid {pid}:tid {threadID}] [client: %{client}] %{message}
RFC3164	{timestamp} {hostname} {application}[{pid}]: {message}
RFC5424	{version} {iso-timestamp} {hostname} {application} {pid} {message-id} {structured-data} {message}
Common Log File Format	%[host]s - %[user]s %[authUserId]d [%[ASC_TIME]s] "%[method]s %[request]s HTTP/1.0" %[responseCode]d %[bytes]d

Metadata

In addition to the keys provided by the user via logger.metadata/1, the following extra keys are available to the :metadata list:

Name	Description
host
application	The current application
module	The current module
function	The current function
file	The current file
line	The current line
pid	The current process identifier
threadID
user
authUserId
method
request
responseCode
bytes