simplifying rsyslog JSON generation

With RESTful APIs, like for example ElasticSearch, you need to generate JSON strings. Rsyslog will soon do this in a very easy to use way. The current method is not hard either, but often looks a bit clumsy. The new way of doing things will most probably be part of the 8.33 release.

You now can define a template as follows:

template(name="outfmt" type="list" option.jsonf="on") {
dateFormat="rfc3339" format="jsonf")
name="hostname" format="jsonf")
name="syslogseverity-text" caseConversion="upper" format="jsonf")
name="syslogfacility-text" format="jsonf")
name="syslogtag" format="jsonf")
name="app-name" format="jsonf")
name="msg" format="jsonf")


This will generate JSON. Here is a pretty-printed version of the generated output:

"@timestamp": "2018-03-01T01:00:00+00:00",
"host": "",
"severity": "DEBUG",
"facility": "local4",
"syslog-tag": "app[1666]",
"source": "app",
"message": " this is my syslog message"

Note: the actual output will be compact on a single “line”, as this is most useful with RESTful APIs.

Future versions of rsyslog may see additional simplifications in generating the JSON. For example, I currently think about removing the need to give format=”jsonf” for each property.
The functionality described here is being added via this pull request.