Comment 6 for bug 1908065

It does not appear that systemd-journald is automatically parsing SYSLOG_IDENTIFIER. The following sample program:

#include <systemd/sd-journal.h>

int main(int argc, char *argv[]) {
    sd_journal_send("MESSAGE=%s", "Hello world!",
                    "SYSLOG_IDENTIFIER=%s", "sssd[sudo]",
                    NULL);
}

produces logs with:

    MESSAGE=Hello world!
    SYSLOG_IDENTIFIER=sssd[sudo]

There is no SYSLOG_PID, and SYSLOG_IDENTIFIER is the literal "sssd[sudo]".

/var/log/syslog also contains: "<timestamp> <hostname> sssd[sudo][12345]: Hello world!"

systemd.journal-fields documentation also states the fields are not explicitly validated, so that implies to me no processing on them should be taking place.