
[[filter_elements]]
= Filter Elements

[partintro]
--
* <<fe_aliases,aliases>>
* <<fe_allocation_type,allocation_type>>
* <<fe_count,count>>
* <<fe_date_from,date_from>>
* <<fe_date_from_format,date_from_format>>
* <<fe_date_to,date_to>>
* <<fe_date_to_format,date_to_format>>
* <<fe_direction,direction>>
* <<fe_disk_space,disk_space>>
* <<fe_epoch,epoch>>
* <<fe_exclude,exclude>>
* <<fe_field,field>>
* <<fe_intersect,intersect>>
* <<fe_key,key>>
* <<fe_kind,kind>>
* <<fe_max_num_segments,max_num_segments>>
* <<fe_pattern,pattern>>
* <<fe_period_type,period_type>>
* <<fe_range_from,range_from>>
* <<fe_range_to,range_to>>
* <<fe_reverse,reverse>>
* <<fe_source,source>>
* <<fe_state,state>>
* <<fe_stats_result,stats_result>>
* <<fe_timestring,timestring>>
* <<fe_threshold_behavior,threshold_behavior>>
* <<fe_unit,unit>>
* <<fe_unit_count,unit_count>>
* <<fe_unit_count_pattern,unit_count_pattern>>
* <<fe_use_age,use_age>>
* <<fe_value,value>>
* <<fe_week_starts_on,week_starts_on>>

You can use <<envvars,environment variables>> in your configuration files.
--



[[fe_aliases]]
== aliases

include::inc_filter_by_aliases.asciidoc[]

NOTE: This setting is used only when using the <<filtertype_alias,alias>>
    filter.

The value of this setting must be a single alias name, or a list of alias names.
This can be done in any of the ways YAML allows for lists or arrays.  Here are
a few examples.

**Single**
[source,txt]
-------
filters:
- filtertype: alias
  aliases: my_alias
  exclude: False
-------

**List**

- Flow style:
+
[source,txt]
-------
filters:
- filtertype: alias
  aliases: [ my_alias, another_alias ]
  exclude: False
-------

- Block style:
+
[source,txt]
-------
filters:
- filtertype: alias
  aliases:
    - my_alias
    - another_alias
  exclude: False
-------

There is no default value. This setting must be set by the user or an
exception will be raised, and execution will halt.


[[fe_allocation_type]]
== allocation_type

NOTE: This setting is used only when using the
    <<filtertype_allocated,allocated>> filter.

[source,yaml]
-------------
- filtertype: allocated
  key: ...
  value: ...
  allocation_type: require
  exclude: True
-------------

The value of this setting must be one of `require`, `include`, or `exclude`.

Read more about these settings in the
{ref}/shard-allocation-filtering.html[Elasticsearch documentation].

The default value for this setting is `require`.



[[fe_count]]
== {es} Curator count filter setting

NOTE: This setting is only used with the <<filtertype_count,count>> filtertype +
    and is a required setting.

[source,yaml]
-------------
- filtertype: count
  count: 10
-------------

The value for this setting is a number of indices or snapshots to match.

Items will remain in the actionable list depending on the value of
<<fe_exclude,exclude>>, and <<fe_reverse,reverse>>.

There is no default value. This setting must be set by the user or an exception
will be raised, and execution will halt.


[[fe_date_from]]
== date_from

NOTE: This setting is only used with the <<filtertype_period,period>> filtertype +
    when <<fe_period_type,period_type>> is `absolute`.

[source,yaml]
-------------
 - filtertype: period
   period_type: absolute
   source: name
   timestring: '%Y.%m.%d'
   unit: months
   date_from: 2017.01
   date_from_format: '%Y.%m'
   date_to: 2017.01
   date_to_format: '%Y.%m'
-------------

The value for this setting should be a date which can be easily parsed
using the strftime string in <<fe_date_from_format,`date_from_format`>>:

include::inc_strftime_table.asciidoc[]

[[fe_date_from_format]]
== date_from_format

NOTE: This setting is only used with the <<filtertype_period,period>> filtertype +
    when <<fe_period_type,period_type>> is `absolute`.

[source,yaml]
-------------
 - filtertype: period
   period_type: absolute
   source: name
   timestring: '%Y.%m.%d'
   unit: months
   date_from: 2017.01
   date_from_format: '%Y.%m'
   date_to: 2017.01
   date_to_format: '%Y.%m'
-------------

The value for this setting should be an strftime string which corresponds to
the date in <<fe_date_from,`date_from`>>:

include::inc_strftime_table.asciidoc[]

[[fe_date_to]]
== date_to

NOTE: This setting is only used with the <<filtertype_period,period>> filtertype +
    when <<fe_period_type,period_type>> is `absolute`.

[source,yaml]
-------------
 - filtertype: period
   period_type: absolute
   source: name
   timestring: '%Y.%m.%d'
   unit: months
   date_from: 2017.01
   date_from_format: '%Y.%m'
   date_to: 2017.01
   date_to_format: '%Y.%m'
-------------

The value for this setting should be a date which can be easily parsed
using the strftime string in <<fe_date_to_format,`date_to_format`>>:

include::inc_strftime_table.asciidoc[]

[[fe_date_to_format]]
== date_to_format

NOTE: This setting is only used with the <<filtertype_period,period>> filtertype +
    when <<fe_period_type,period_type>> is `absolute`.

[source,yaml]
-------------
 - filtertype: period
   period_type: absolute
   source: name
   timestring: '%Y.%m.%d'
   unit: months
   date_from: 2017.01
   date_from_format: '%Y.%m'
   date_to: 2017.01
   date_to_format: '%Y.%m'
-------------

The value for this setting should be an strftime string which corresponds to
the date in <<fe_date_to,`date_to`>>:

include::inc_strftime_table.asciidoc[]


[[fe_direction]]
== direction

NOTE: This setting is only used with the <<filtertype_age,age>> filtertype.

[source,yaml]
-------------
 - filtertype: age
   source: creation_date
   direction: older
   unit: days
   unit_count: 3
-------------

This setting must be either `older` or `younger`.  This setting is used to
determine whether indices or snapshots are `older` or `younger` than the
reference point in time determined by <<fe_unit,unit>>,
<<fe_unit_count,unit_count>>, and optionally, <<fe_epoch,epoch>>.  If
`direction` is `older`, then indices (or snapshots) which are _older_ than the
reference point in time will be matched.  Likewise, if `direction` is
`younger`, then indices (or snapshots) which are _younger_ than the reference
point in time will be matched.

There is no default value. This setting must be set by the user or an
exception will be raised, and execution will halt.



[[fe_disk_space]]
== disk_space

NOTE: This setting is only used with the <<filtertype_space,space>> filtertype +
    and is a required setting.

[source,yaml]
-------------
- filtertype: space
  disk_space: 100
-------------

The value for this setting is a number of gigabytes.

Indices in excess of this number of gigabytes will be matched.

There is no default value. This setting must be set by the user or an exception
will be raised, and execution will halt.



[[fe_epoch]]
== epoch

NOTE: This setting is available in the <<filtertype_age,age>> filtertype, and
  any filter which has the <<fe_use_age,`use_age`>> setting. This setting is
  strictly optional.

TIP: This setting is not common.  It is most frequently used for testing.

<<fe_unit,unit>>, <<fe_unit_count,unit_count>>, and optionally,
<<fe_epoch,epoch>>, are used by Curator to establish the moment in time point of
reference with this formula:

[source,sh]
-----------
point_of_reference = epoch - ((number of seconds in unit) * unit_count)
-----------

If <<fe_epoch,epoch>> is unset, the current time is used. It is possible to set
a point of reference in the future by using a negative value for
<<fe_unit_count,unit_count>>.

=== Example

[source,yaml]
-------------
 - filtertype: age
   source: creation_date
   direction: older
   unit: days
   unit_count: 3
   epoch: 1491577200
-------------

The value for this setting must be an epoch timestamp. In this example, the
given epoch time of `1491577200` is 2017-04-04T15:00:00Z (UTC).  This will use
3 days older than that timestamp as the point of reference for age comparisons.



[[fe_exclude]]
== exclude

NOTE: This setting is available in _all_ filter types.

If `exclude` is `True`, the filter will remove matches from the actionable list.
If `exclude` is `False`, then only matches will be kept in the actionable list.

The default value for this setting is different for each filter type.

=== Examples

[source,yaml]
-------------
- filtertype: opened
  exclude: True
-------------

This filter will result in only `closed` indices being in the actionable list.

[source,yaml]
-------------
- filtertype: opened
  exclude: False
-------------

This filter will result in only `open` indices being in the actionable list.



[[fe_field]]
== field

NOTE: This setting is available in the <<filtertype_age,age>> filtertype, and
  any filter which has the <<fe_use_age,`use_age`>> setting. This setting is
  strictly optional.

[source,yaml]
-------------
 - filtertype: age
   source: field_stats
   direction: older
   unit: days
   unit_count: 3
   field: '@timestamp'
   stats_result: min_value
-------------

The value of this setting must be a timestamp field name.  This field must be
present in the indices being filtered or an exception will be raised, and
execution will halt.

In Curator 5.3 and older, source `field_stats` uses the
http://www.elastic.co/guide/en/elasticsearch/reference/5.6/search-field-stats.html[Field Stats API]
to calculate either the `min_value` or the `max_value` of the <<fe_field,`field`>>
as the <<fe_stats_result,`stats_result`>>, and then use that value for age
comparisons.  In 5.4 and above, even though it is still called `field_stats`, it
uses an aggregation to calculate the same values, as the `field_stats` API is
no longer used in Elasticsearch 6.x and up.

This setting is only used when <<fe_source,source>> is `field_stats`.

The default value for this setting is `@timestamp`.



[[fe_intersect]]
== intersect

NOTE: This setting is only available in the <<filtertype_age,period>> filtertype.
   This setting is strictly optional.

[source,yaml]
-------------
 - filtertype: period
   source: field_stats
   direction: older
   intersect: true
   unit: weeks
   range_from: -1
   range_to: -1
   field: '@timestamp'
   stats_result: min_value
-------------

The value of this setting must be `True` or `False`.

`field_stats` uses an aggregation query to
calculate either the `min_value` and the `max_value` of the <<fe_field,`field`>>
as the <<fe_stats_result,`stats_result`>>.  If `intersect` is `True`, then
only indices where the `min_value` _and_ the `max_value` are within the `range_from`
and `range_to` (relative to `unit`) will match.  This means that either `min_value`
or `max_value` can be used for <<fe_stats_result,`stats_result`>> when `intersect`
is `True` with identical results.

This setting is only used when <<fe_source,source>> is `field_stats`.

The default value for this setting is `False`.



[[fe_key]]
== key

NOTE: This setting is required when using the
    <<filtertype_allocated,allocated filtertype>>.

[source,yaml]
-------------
- filtertype: allocated
  key: ...
  value: ...
  allocation_type:
  exclude: True
-------------

The value of this setting should correspond to a node setting on one or more
nodes in your cluster.

For example, you might have set

[source,sh]
-----------
node.tag: myvalue
-----------

in your `elasticsearch.yml` file for one or more of your nodes.  To match
allocation in this case, set key to `tag`.

These special attributes are also supported:

[cols="2*", options="header"]
|===
|attribute
|description

|`_name`
|Match nodes by node name

|`_host_ip`
|Match nodes by host IP address (IP associated with hostname)

|`_publish_ip`
|Match nodes by publish IP address

|`_ip`
|Match either `_host_ip` or `_publish_ip`

|`_host`
|Match nodes by hostname
|===

There is no default value. This setting must be set by the user or an exception
will be raised, and execution will halt.



[[fe_kind]]
== kind

NOTE: This setting is only used with the <<filtertype_pattern,pattern>> +
    filtertype and is a required setting.

This setting tells the <<filtertype_pattern,pattern>> what pattern type to
match. Acceptable values for this setting are `prefix`, `suffix`, `timestring`,
and `regex`.

include::inc_filter_chaining.asciidoc[]

There is no default value. This setting must be set by the user or an exception
will be raised, and execution will halt.

include::inc_kinds.asciidoc[]



[[fe_max_num_segments]]
== max_num_segments

NOTE: This setting is only used with the <<filtertype_forcemerged,forcemerged>>
  filtertype.

[source,yaml]
-------------
- filtertype: forcemerged
  max_num_segments: 2
  exclude: True
-------------

The value for this setting is the cutoff number of segments per shard.  Indices
which have this number of segments per shard, or fewer, will be actionable
depending on the value of <<fe_exclude,exclude>>, which is `True` by default for
the <<filtertype_forcemerged,forcemerged>> filter type.

There is no default value. This setting must be set by the user or an exception
will be raised, and execution will halt.



[[fe_pattern]]
== pattern

NOTE: This setting is only used with the <<filtertype_count,count>> filtertype

[source,yaml]
-------------
- filtertype: count
  count: 1
  pattern: '^(.*)-\d{6}$'
  reverse: true
-------------

This particular example will match indices following the basic rollover pattern
of `indexname-######`, and keep the highest numbered index for each group.

For example, given indices `a-000001`, `a-000002`, `a-000003` and `b-000006`,
and `b-000007`, the indices will would be matched are `a-000003` and `b-000007`.
Indices that do not match the regular expression in `pattern` will be
automatically excluded.

This is particularly useful with indices created and managed using the
{ref}/indices-rollover-index.html[Rollover API], as you can select only the
active indices with the above example (<<fe_exclude,`exclude`>> defaults to `False`).
Setting <<fe_exclude,`exclude`>> to `True` with the above example will _remove_
the active rollover indices, leaving only those which have been rolled-over.

While this is perhaps most useful for the aforementioned scenario, it can
also be used with age-based indices as well.

Items will remain in the actionable list depending on the value of
<<fe_exclude,exclude>>, and <<fe_reverse,reverse>>.

There is no default value. The value must include a capture group, defined by
parenthesis, or left empty.  If a value is provided, and there is no capture
group, and exception will be raised and execution will halt.


[[fe_period_type]]
== period_type

NOTE: This setting is only used with the <<filtertype_period,period>> filtertype

[source,yaml]
-------------
 - filtertype: period
   period_type: absolute
   source: name
   timestring: '%Y.%m.%d'
   unit: months
   date_from: 2017.01
   date_from_format: '%Y.%m'
   date_to: 2017.01
   date_to_format: '%Y.%m'
-------------

The value for this setting must be either `relative` or `absolute`. The default
value is `relative`.


[[fe_range_from]]
== range_from

NOTE: This setting is only used with the <<filtertype_period,period>> filtertype

[source,yaml]
-------------
 - filtertype: period
   source: name
   range_from: -1
   range_to: -1
   timestring: '%Y.%m.%d'
   unit: days
-------------

<<fe_range_from,range_from>> and <<fe_range_to,range_to>> are counters of whole
<<fe_unit,units>>. A negative number indicates a whole unit in the past, while
a positive number indicates a whole unit in the future. A `0` indicates the
present unit.

Read more about this setting in context in the
<<filtertype_period,period filtertype documentation>>, including examples.



[[fe_range_to]]
== range_to

NOTE: This setting is only used with the <<filtertype_period,period>> filtertype

[source,yaml]
-------------
 - filtertype: period
   source: name
   range_from: -1
   range_to: -1
   timestring: '%Y.%m.%d'
   unit: days
-------------

<<fe_range_from,range_from>> and <<fe_range_to,range_to>> are counters of whole
<<fe_unit,units>>. A negative number indicates a whole unit in the past, while
a positive number indicates a whole unit in the future. A `0` indicates the
present unit.

Read more about this setting in context in the
<<filtertype_period,period filtertype documentation>>, including examples.



[[fe_reverse]]
== reverse

NOTE: This setting is used in the <<filtertype_count,count>> and
 <<filtertype_space,space>> filtertypes

This setting affects the sort order of the indices.  `True` means
reverse-alphabetical.  This means that if all index names share the same pattern
with a date--e.g. index-2016.03.01--older indices will be selected first.

The default value of this setting is `True`.

This setting is ignored if <<fe_use_age,use_age>> is `True`.

TIP: There are context-specific examples of how `reverse` works in the
  <<filtertype_count,count>> and <<filtertype_space,space>> documentation.



[[fe_source]]
== source
The _source_ from which to derive the index or snapshot age. Can be one of
`name`, `creation_date`, or `field_stats`.

NOTE: This setting is only used with the <<filtertype_age,age>> filtertype, or +
with the <<filtertype_space,space>> filtertype when <<fe_use_age,use_age>> is
set to `True`.

NOTE: When using the <<filtertype_age,age>> filtertype, source requires +
<<fe_direction,direction>>, <<fe_unit,unit>>, <<fe_unit_count,unit_count>>, +
and additionally, the optional setting, <<fe_epoch,epoch>>.

include::inc_sources.asciidoc[]



[[fe_state]]
== state

NOTE: This setting is only used with the <<filtertype_state,state>> filtertype.

[source,yaml]
-------------
- filtertype: state
  state: SUCCESS
-------------

The value for this setting must be one of `SUCCESS`, `PARTIAL`, `FAILED`,
or `IN_PROGRESS`.  This setting determines what kind of snapshots will be
passed.

The default value for this setting is `SUCCESS`.



[[fe_stats_result]]
== stats_result

NOTE: This setting is only used with the <<filtertype_age,age>> filtertype.

[source,yaml]
-------------
 - filtertype: age
   source: field_stats
   direction: older
   unit: days
   unit_count: 3
   field: '@timestamp'
   stats_result: min_value
-------------

The value for this setting can be either `min_value` or `max_value`.  This
setting is only used when <<fe_source,source>> is `field_stats`, and determines
whether Curator will use the minimum or maximum value of <<fe_field,field>> for
time calculations.

The default value for this setting is `min_value`.



[[fe_timestring]]
== timestring

NOTE: This setting is only used with the <<filtertype_age,age>> filtertype, or +
with the <<filtertype_space,space>> filtertype if <<fe_use_age,use_age>> is
set to `True`.


=== strftime

This setting must be a valid Python strftime string.  It is used to match and
extract the timestamp in an index or snapshot name.

include::inc_strftime_table.asciidoc[]

These identifiers may be combined with each other, and/or separated from each
other with hyphens `-`, periods `.`, underscores `_`, or other characters valid
in an index name.

Each identifier must be preceded by a `%` character in the timestring.  For
example, an index like `index-2016.04.01` would use a timestring of
`'%Y.%m.%d'`.

When <<fe_source,source>> is `name`, this setting must be set by the user or an
exception will be raised, and execution will halt. There is no default value.

include::inc_timestring_regex.asciidoc[]



[[fe_threshold_behavior]]
== threshold_behavior

NOTE: This setting is only available in the <<filtertype_space,space>> filtertype.
  This setting is optional, and defaults to `greater_than` to preserve backwards compatability.

[source,yaml]
-------------
- filtertype: space
  disk_space: 5
  threshold_behavior: less_than
-------------

The value for this setting is `greater_than` (default) or `less_than`.

When set to `less_than`, indices in less than `disk_space` gigabytes will be matched.
When set to `greater_than` (default), indices larger than `disk_space` will be matched.



[[fe_unit]]
== unit

NOTE: This setting is used with the <<filtertype_age,age>> filtertype, with the
<<filtertype_period,period>> filtertype, or with the <<filtertype_space,space>>
filtertype if <<fe_use_age,use_age>> is set to `True`.

[source,yaml]
-------------
 - filtertype: age
   source: creation_date
   direction: older
   unit: days
   unit_count: 3
-------------

This setting must be one of `seconds`, `minutes`, `hours`, `days`, `weeks`,
`months`, or `years`. The values `seconds` and `minutes` are not allowed with
the <<filtertype_period,period>> filtertype and will result in an error
condition if used there.

For the <<filtertype_age,age>> filtertype, or when <<fe_use_age,use_age>> is set
to `True`, <<fe_unit,unit>>, <<fe_unit_count,unit_count>>, and optionally,
<<fe_epoch,epoch>>, are used by Curator to establish the moment in time point of
reference with this formula:

[source,sh]
-----------
point_of_reference = epoch - ((number of seconds in unit) * unit_count)
-----------

include::inc_unit_table.asciidoc[]


If <<fe_epoch,epoch>> is unset, the current time is used. It is possible to set
a point of reference in the future by using a negative value for
<<fe_unit_count,unit_count>>.

This setting must be set by the user or an exception will be raised, and
execution will halt.

TIP: See the <<filtertype_age,age filter documentation>> for more information
  about time calculation.



[[fe_unit_count]]
== unit_count

NOTE: This setting is only used with the <<filtertype_age,age>> filtertype, or +
with the <<filtertype_space,space>> filtertype if <<fe_use_age,use_age>> is
set to `True`.

[source,yaml]
-------------
 - filtertype: age
   source: creation_date
   direction: older
   unit: days
   unit_count: 3
-------------

The value of this setting will be used as a multiplier for <<fe_unit,unit>>.

<<fe_unit,unit>>, <<fe_unit_count,unit_count>>, and optionally,
<<fe_epoch,epoch>>, are used by Curator to establish the moment in time point of
reference with this formula:

[source,sh]
-----------
point_of_reference = epoch - ((number of seconds in unit) * unit_count)
-----------

include::inc_unit_table.asciidoc[]

If <<fe_epoch,epoch>> is unset, the current time is used. It is possible to set
a point of reference in the future by using a negative value for
<<fe_unit_count,unit_count>>.

This setting must be set by the user or an exception will be raised, and
execution will halt.

If this setting is used in conjunction with <<fe_unit_count_pattern,unit_count_pattern>>, the configured
value will only be used as a fallback value in case the pattern could not be matched. The value _-1_ has
a special meaning in this case and causes the index to be ignored when pattern matching fails.

TIP: See the <<filtertype_age,age filter documentation>> for more information
  about time calculation.



[[fe_unit_count_pattern]]
== unit_count_pattern

NOTE: This setting is only used with the age filtertype to define, whether the
<<fe_unit_count,unit_count>> value is taken from the configuration or read from
the index name via a regular expression.

[source,yaml]
-------------
 - filtertype: age
   source: creation_date
   direction: older
   unit: days
   unit_count: 3
   unit_count_pattern: -([0-9]+)-
-------------

This setting can be used in cases where the value against which index age should be assessed is not a static
value but can be different for every index. For this case, there is the option of extracting the index
specific value from the index names via a regular expression defined in this parameter.

Consider for example the following index name patterns that contain the retention time in their name:
_logstash-30-yyyy.mm.dd_, _logstash-12-yyyy.mm_, __3_logstash-yyyy.mm.dd_.

To extract a value from the index names, this setting will be compiled as a regular expression and matched
against index names, for a successful match, the value of the first capture group from the regular expression
is used as the value for <<fe_unit_count,unit_count>>.

If there is any error during compiling or matching the expression, or the expression does not
contain a capture group, the value configured in <<fe_unit_count,unit_count>> is used as a fallback value,
unless it is set to _-1_, in which case the index will be skipped.

TIP: Regular expressions and match groups are not explained here as they are a fairly large and complex topic,
but there are numerous resources online that will help. Using an online tool for testing regular expressions
like https://regex101.com/[regex101.com] will help a lot when developing patterns.

*Examples*

* _logstash-30-yyyy.mm.dd_: Daily index that should be deleted after 30 days, indices that
don't match the pattern will be deleted after 365 days
[source,yaml]
-------------
 - filtertype: age
   source: creation_date
   direction: older
   unit: days
   unit_count: 365
   unit_count_pattern: -([0-9]+)-
-------------


* _logstash-12-yyyy.mm_: Monthly index that should be deleted after 12 months, indices that
don't match the pattern will be deleted after 3 months

[source,yaml]
-------------
 - filtertype: age
   source: creation_date
   direction: older
   unit: months
   unit_count: 3
   unit_count_pattern: -([0-9]+)-
-------------


* __3_logstash-yyyy.mm.dd_: Daily index that should be deleted after 3 years, indices that
don't match the pattern will be ignored

[source,yaml]
-------------
 - filtertype: age
   source: creation_date
   direction: older
   unit: years
   unit_count: -1
   unit_count_pattern: ^_([0-9]+)_
-------------

IMPORTANT: Be sure to pay attention to the interaction of this parameter and <<fe_unit_count,unit_count>>!


[[fe_use_age]]
== use_age

[source,yaml]
-------------
- filtertype: count
  count: 10
  use_age: True
  source: creation_date
-------------

This setting allows filtering of indices by their age _after_ other
considerations.

The default value of this setting is `False`

NOTE: Use of this setting requires the additional setting, <<fe_source,source>>.

TIP: There are context-specific examples using `use_age` in the
  <<filtertype_count,count>> and <<filtertype_space,space>> documentation.



[[fe_value]]
== value

NOTE: This setting is only used with the <<filtertype_pattern,pattern>>
filtertype and is a required setting.  There is a separate
  <<option_value,value option>> associated with the
  <<allocation,allocation action>>, and the
  <<filtertype_allocated,allocated filtertype>>.

The value of this setting is used by <<fe_kind,kind>> as follows:

* `prefix`: Search the first part of an index name for the provided value
* `suffix`: Search the last part of an index name for the provided value
* `regex`: Provide your own regular expression, and Curator will find the matches.
* `timestring`: An strftime string to extrapolate and find indices that match.
    For example, given a `timestring` of `'%Y.%m.%d'`, matching indices would
    include `logstash-2016.04.01` and `.marvel-2016.04.01`, but not
    `myindex-2016-04-01`, as the pattern is different.

IMPORTANT: Whatever you provide for `value` is always going to be a part of a +
    regular expression.  The safest practice is to always encapsulate within
    single quotes.  For example: `value: '-suffix'`, or `value: 'prefix-'`

There is no default value. This setting must be set by the user or an exception
will be raised, and execution will halt.

TIP: There are context-specific examples using `value` in the <<fe_kind,kind>>
  documentation.



[[fe_week_starts_on]]
== week_starts_on

NOTE: This setting is only used with the <<filtertype_period,period>> filtertype +
    when <<fe_period_type,period_type>> is `relative`.

[source,yaml]
-------------
 - filtertype: period
   source: name
   range_from: -1
   range_to: -1
   timestring: '%Y.%m.%d'
   unit: weeks
   week_starts_on: sunday
-------------

The value of this setting indicates whether weeks should be measured starting on
`sunday` or `monday`.  Though Monday is the ISO standard, Sunday is frequently
preferred.

This setting is only used when <<fe_unit,unit>> is set to `weeks`.

The default value for this setting is `sunday`.
