Crate flexi_logger

A flexible and easy-to-use logger that writes logs to stderr and/or to files or other output streams.

To read the log specification from an environment variable and get the log written to stderr, start flexi_logger e.g. like this:

flexi_logger::Logger::with_env().start().unwrap();

See

• Logger for a full description of all configuration options,
• and the writers module for the usage of additional log writers,
• and the homepage for how to get started.

There are configuration options to e.g.

• decide whether you want to write your logs to stderr or to a file,
• configure the path and the filenames of the log files,
• use file rotation,
• specify the line format for the log lines,
• define additional log output streams, e.g for alert or security messages,
• support changing the log specification while the program is running,

flexi_logger uses a similar syntax as env_logger for specifying which logs should really be written (but is more graceful with the syntax, and can provide error information).

By default, i.e. if feature colors is not switched off, the log lines that appear on your terminal are coloured. In case the chosen colors don’t fit to your terminal’s color theme, you can adapt the colors to improve readability. See the documentation of method style for a description how this can be done.

Modules

code_examples	Here are some examples for the flexi_logger initialization.
writers	Contains the trait LogWriter for extending flexi_logger with additional log writers, and two concrete implementations for writing to files (FileLogWriter) or to the syslog (SyslogWriter). You can also use your own implementations of LogWriter.

Structs

DeferredNow	Deferred timestamp creation.
LogSpecBuilder	Builder for LogSpecification.
LogSpecification	Immutable struct that defines which loglines are to be written, based on the module, the log level, and the text.
Logger	The entry-point for using flexi_logger.
LoggerHandle	Allows reconfiguring the logger programmatically.
ModuleFilter	Defines which loglevel filter to use for the specified module.
Record	Re-exports from log crate

Enums

AdaptiveFormat	Specifies the FormatFunction and decides if coloring should be used.
Age	The age after which a log file rotation will be triggered, when Criterion::Age is chosen.
Cleanup	Defines the strategy for handling older log files.
Criterion	Criterion when to rotate the log file.
Duplicate	Used to control which messages are to be duplicated to stderr, when log_to_file() is used.
FlexiLoggerError	Describes errors in the initialization of flexi_logger.
Level	Re-exports from log crate
LevelFilter	Re-exports from log crate
LogTarget	Describes the default log target.
Naming	The naming convention for rotated log files.

Functions

colored_default_format	A colored version of the logline-formatter default_format that produces log lines like ERROR [my_prog::some_submodule] File not found
colored_detailed_format	A colored version of the logline-formatter detailed_format.
colored_opt_format	A colored version of the logline-formatter opt_format.
colored_with_thread	A colored version of the logline-formatter with_thread.
default_format	A logline-formatter that produces log lines like INFO [my_prog::some_submodule] Task successfully read from conf.json
detailed_format	A logline-formatter that produces log lines like [2016-01-13 15:25:01.640870 +01:00] INFO [foo::bar] src/foo/bar.rs:26: Task successfully read from conf.json i.e. with timestamp, module path and file location.
opt_format	A logline-formatter that produces log lines with timestamp and file location, like [2016-01-13 15:25:01.640870 +01:00] INFO [src/foo/bar:26] Task successfully read from conf.json
style	Helper function that is used in the provided coloring format functions to apply colors based on the log level and the effective color palette.
with_thread	A logline-formatter that produces log lines like [2016-01-13 15:25:01.640870 +01:00] T[taskreader] INFO [src/foo/bar:26] Task successfully read from conf.json i.e. with timestamp, thread name and file location.

Type Definitions

FormatFunction	Function type for Format functions.
ReconfigurationHandle	Deprecated For backwards compatibility.