<Extension _json>
    Module      xm_json
    DateFormat YYYY-MM-DD hh:mm:ss
</Extension>

<Extension _syslog>
    Module      xm_syslog
</Extension>

<Extension python>
    Module      xm_python
    PythonCode  "modules/extension/python/py/processlogs2.py"
</Extension>

<Output out>
    Module      om_file
    File        'tmp/output'
    <Exec>
        # The $SeverityValue field is added by this procedure.
        # Most other parsers also add a normalized severity value.
        parse_syslog();

        # Add a counter for each event with log level above DEBUG.
        python_call('add_counter');

        # Calculate a checksum (after the counter field is added).
        python_call('add_checksum');

        # Convert to JSON format
        to_json();
    </Exec>
</Output>

import hashlib

import nxlog

def add_checksum(event):
    # Convert field list to dictionary
    all = {}
    for field in event.field_names():
        all.update({field: event.get_field(field)})

    # Calculate checksum and add to event record
    checksum = hashlib.sha1(repr(sorted(all)).encode('utf-8')).hexdigest()
    event.set_field('ChecksumSHA1', checksum)
    nxlog.log_debug('Added checksum field')

def add_counter(event):
    # Get module object and initialize counter
    module = event.module
    if not 'counter' in module:
        module['counter'] = 0
        nxlog.log_debug('Initialized counter field')

    # Skip DEBUG messages
    severity = event.get_field('SeverityValue')
    if severity > 1:
        # Add field
        event.set_field('Counter', module['counter'])
        nxlog.log_debug('Added counter field')

        # Increment counter
        module['counter'] += 1
        nxlog.log_debug('Incremented counter')