pattern
editpattern
edit- filtertype: pattern kind: ... value: ...
Empty values and commented lines will result in the default value, if any, being selected. If a setting is set, but not used by a given filtertype, it may generate an error.
This filtertype will iterate over the actionable list and match indices matching a given pattern. They will remain in, or be removed from the actionable list based on the value of exclude.
Filter chaining
It is important to note that while filters can be chained, each is linked by an implied logical AND operation. If you want to match from one of several different patterns, as with a logical OR operation, you can do so with the pattern filtertype using regex as the kind.
This example shows how to select multiple indices based on them beginning with
either alpha-, bravo-, or charlie-:
filters:
- filtertype: pattern
kind: regex
value: '^(alpha-|bravo-|charlie-).*$'
Explaining all of the different ways in which regular expressions can be used is outside the scope of this document, but hopefully this gives you some idea of how a regular expression pattern can be used when a logical OR is desired.
The different kinds are described as follows:
prefix
editTo match all indices starting with logstash-:
- filtertype: pattern kind: prefix value: logstash-
To match all indices except those starting with logstash-:
- filtertype: pattern kind: prefix value: logstash- exclude: True
suffix
editTo match all indices ending with -prod:
- filtertype: pattern kind: suffix value: -prod
To match all indices except those ending with -prod:
- filtertype: pattern kind: suffix value: -prod exclude: True
timestring
editNo age calculation takes place here. It is strictly a pattern match.
To match all indices with a Year.month.day pattern, like index-2017.04.01:
- filtertype: pattern kind: timestring value: '%Y.%m.%d'
To match all indices except those with a Year.month.day pattern, like
index-2017.04.01:
- filtertype: pattern kind: timestring value: '%Y.%m.%d' exclude: True
A word about regular expression matching with timestrings
Timestrings are parsed from strftime patterns, like %Y.%m.%d, into regular
expressions. For example, %Y is 4 digits, so the regular expression for that
looks like \d{4}, and %m is 2 digits, so the regular expression is \d{2}.
What this means is that a simple timestring to match year and month, %Y.%m
will result in a regular expression like this: ^.*\d{4}\.\d{2}.*$. This
pattern will match any 4 digits, followed by a period ., followed by 2 digits,
occurring anywhere in the index name. This means it will match monthly
indices, like index-2016.12, as well as daily indices, like
index-2017.04.01, which may not be the intended behavior.
To compensate for this, when selecting indices matching a subset of another
pattern, use a second filter with exclude set to True
- filtertype: pattern kind: timestring value: '%Y.%m' - filtertype: pattern kind: timestring value: '%Y.%m.%d' exclude: True
This will prevent the %Y.%m pattern from matching the %Y.%m part of the
daily indices.
This applies whether using timestring as a mere pattern match, or as part of
date calculations.
regex
editThis kind allows you to design a regular-expression to match
indices or snapshots:
To match all indices starting with a-, b-, or c-:
- filtertype: pattern kind: regex value: '^a-|^b-|^c-'
To match all indices except those starting with a-, b-, or c-:
- filtertype: pattern kind: regex value: '^a-|^b-|^c-' exclude: True