flux_log(3)

SYNOPSIS

#include <flux/core.h>

int flux_vlog (flux_t *h, int level, const char *fmt, va_list ap);

int flux_log (flux_t *h, int level, const char *fmt, …​);

void flux_log_set_appname (flux_t *h, const char *s);

void flux_log_set_procid (flux_t *h, const char *s);

DESCRIPTION

flux_log() creates RFC 5424 format log messages. The log messages are sent to the Flux message broker on h for handling if it is specified. If h is NULL, the log message is output to stderr.

The level parameter should be set to one of the syslog(3) severity levels, which are, in order of decreasing importance:

LOG_EMERG

system is unusable

LOG_ALERT

action must be taken immediately

LOG_CRIT

critical conditions

LOG_ERR

error conditions

LOG_WARNING

warning conditions

LOG_NOTICE

normal, but significant, condition

LOG_INFO

informational message

LOG_DEBUG

debug-level message

When h is specified, log messages are are added to the broker's circular buffer which can be accessed with flux-dmesg(1). From there, a message's disposition is up to the broker's log configuration.

flux_log_set_procid() may be used to override the default procid, which is initialized to the calling process's PID.

flux_log_set_appname() may be used to override the default application name, which is initialized to the value of the __progname symbol (normally the argv[0] program name).

MAPPING TO SYSLOG

A Flux log message is formatted as a Flux request with a "raw" payload, as defined by Flux RFC 3. The raw payload is formatted according to Internet RFC 5424.

If the Flux handle h is specified, the following Syslog header fields are set in a Flux log messages when it is created within flux_log():

PRI

Set to the user-specified severity level combined with the facility, which is hardwired to LOG_USER in Flux log messages.

VERSION

Set to 1.

TIMESTAMP

Set to the current UTC wallclock time.

HOSTNAME

Set to the broker rank associated with h.

APP-NAME

Set to the user-defined application name, truncated to 48 characters, excluding terminating NULL.

PROCID

Set to the PID of the calling process.

MSGID

Set to the NIL string "-".

The STRUCTURED-DATA portion of the message is empty, and reserved for future use by Flux.

The MSG portion is post-processed to ensure it contains no NULL's or non-ASCII characters. At this time non-ASCII UTF-8 is not supported by flux_log().

RETURN VALUE

flux_log() normally returns 0 on success, or -1 if there was a problem building or sending the log message, with errno set.

ERRORS

EPERM

The user does not have permission to log messages to this Flux instance.

ENOMEM

Out of memory.

RESOURCES

Flux: http://flux-framework.org

RFC 5424 The Syslog Protocol: https://tools.ietf.org/html/rfc5424

SEE ALSO

flux-dmesg(1), flux-logger(1),