struCtured-logger

struCtured-logger is a simple JSON logger for C applications. This first version only supports strings for the key types but I'm working on another version to support numbers and boolean values.

Use

To use this library, call the log macro. This macro takes a log level, a string key, and a log value. The values supported are int, int64, double, and string. To use one of those as a value, the value needs to be passed as a parameter to one of the associated functions. Ie log_int64(6789).

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 "log.h"

int
main(int argc, char **argv)
{
    log_init(stdout);
    log(LOG_INFO, "msg", log_string("records added successfully"), "count", log_int(2));
    log(LOG_INFO, "msg", log_string("records added successfully"), "count", log_int64(9223372036854775807));
    log(LOG_INFO, "msg", log_string("records added partially"), "count", log_int64(3.14));
    log(LOG_INFO, "msg", log_string("record added successfully"), "name", log_string("Brian"), "elapsed", log_double(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");
if (f == NULL) {
    perror("couldn't open file.log");
    return 1;
}
log_init(f);
log(LOG_INFO, "msg", log_string("records added successfully"), "count", log_int(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

Apache License.