Very custom date format in momentjs

Question

I am working with kibana (elasticsearch dashboard) which allow to specify a date pattern to explain the index naming pattern.

For instance, default pattern is: [logstash-]YYYY-MM-DD.HH

I'd like to organize my index by block of hours, let's say by block of 4 hours. Indices would then be named logstash-2014-02-25.00, logstash-2014-02-25.04, logstash-2014-02-25.08, …

Is there any way to get such format with momentjs ? I am dreaming of [logstash-]YYYY-MM-DD.{HH%4} but the documentation does not explain such thing (how weird).

Answer 1

It seems impossible to do it with formatting primitives.

However, I found we can override some of the language-dependant formatter such as meridiem formatter. A solution would then be to insert somewhere (in kibana conf file for example):

moment.lang('fourHourblocks', {
  meridiem: function(hour, minute, isLowercase) {
    hourBlock = Math.floor(hour / 4).toString();
    if (hourBlock.length < 2) hourBlock = "0" + hourBlock;
    return hourBlock;
  }
}

then I can set the pattern to [logstash-]YYYY-MM-DD.A.

This is kind of hacky so I am still opened to other solutions