briandowns / liblogger

A simple and performant, single-header JSON structured logger for C applications.

liblogger

liblogger is a simple JSON logger in C.

Use

To use this single-header library, call the log macro. This macro takes a log level, any number of log_field_t pointers containing a string key and a log value.

The supported int values are: int, int8, int16, int32, int64 The supported uint values are: uint, uint8, uint16, uint32, uint64

As well as double, and string.

The supported log levels are: trace, debug, info, warn, error, fatal,

For a successful log entry to be made, a key and a value need to be provided. If no value is provided, that field will not be logged.

Example

Build the example:

make example

#include <stdio.h>

#include "logger.h"

int
main(int argc, char **argv)
{
    log_init(stdout);
    log(log_INFO, 
        log_string("msg", "records added successfully"), 
        log_uint8("count", 2));
    log(log_INFO, 
        log_string("msg", "records added successfully"), 
        log_int64("count", 9223372036854775807));
    log(log_INFO, 
        log_string("msg", "records added partially"), 
        log_double("count", 3.14));
    log(log_INFO, 
        log_string("msg", "record added successfully"), 
        log_string("name", "Brian"), 
        log_double("elapsed", 5.76)); 
}

Expected output:

{ "timestamp": 1541620673, "level": "info", "msg": "records added successfully", "count": 2 }
{ "timestamp": 1541620673, "level": "info", "msg": "records added successfully", "count": 9223372036854775807 }
{ "timestamp": 1541620673, "level": "info", "msg": "records added partially", "count": 3 }
{ "timestamp": 1541620673, "level": "info", "msg": "record added successfully", "name": "Brian", "elapsed": 5.7599999999999998 }

Write to a log file:

FILE *f = fopen("file.log", "w");
log_init(f);
log(log_INFO, log_string("msg", "records added successfully"), log_uint8("count", 2));
fclose(f);

Requirements

• json-c

Lots of thanks to Ayan George for the help with getting this where it is.

Contact

Brian Downs @bdowns328

License

BSD 2 Clause License.