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Regex Processor Plugin

This plugin transforms tag and field values as well as renaming tags, fields and metrics using regex patterns. Tag and field values can be transformed using named-groups in a batch fashion.

The regex processor only operates on string fields. It will not work on any other data types, like an integer or float.

Global configuration options

In addition to the plugin-specific configuration settings, plugins support additional global and plugin configuration settings. These settings are used to modify metrics, tags, and field or create aliases and configure ordering, etc. See the CONFIGURATION.md for more details.

Configuration

# Transforms tag and field values as well as measurement, tag and field names with regex pattern
[[processors.regex]]
  namepass = ["nginx_requests"]

  ## Tag value conversion(s). Multiple instances are allowed.
  [[processors.regex.tags]]
    ## Tag(s) to process with optional glob expressions such as '*'.
    key = "resp_code"
    ## Regular expression to match the tag value. If the value doesn't
    ## match the tag is ignored.
    pattern = "^(\\d)\\d\\d$"
    ## Replacement expression defining the value of the target tag. You can
    ## use regexp groups or named groups e.g. ${1} references the first group.
    replacement = "${1}xx"
    ## Name of the target tag defaulting to 'key' if not specified.
    ## In case of wildcards being used in `key` the currently processed
    ## tag-name is used as target.
    # result_key = "method"
    ## Appends the replacement to the target tag instead of overwriting it when
    ## set to true.
    # append = false

  ## Field value conversion(s). Multiple instances are allowed.
  [[processors.regex.fields]]
    ## Field(s) to process with optional glob expressions such as '*'.
    key = "request"
    ## Regular expression to match the field value. If the value doesn't
    ## match or the field doesn't contain a string the field is ignored.
    pattern = "^/api(?P<method>/[\\w/]+)\\S*"
    ## Replacement expression defining the value of the target field. You can
    ## use regexp groups or named groups e.g. ${method} references the group
    ## named "method".
    replacement = "${method}"
    ## Name of the target field defaulting to 'key' if not specified.
    ## In case of wildcards being used in `key` the currently processed
    ## field-name is used as target.
    # result_key = "method"

  ## Rename metric fields
  [[processors.regex.field_rename]]
    ## Regular expression to match on the field name
    pattern = "^search_(\\w+)d$"
    ## Replacement expression defining the name of the new field
    replacement = "${1}"
    ## If the new field name already exists, you can either "overwrite" the
    ## existing one with the value of the renamed field OR you can "keep"
    ## both the existing and source field.
    # result_key = "keep"

  ## Rename metric tags
  [[processors.regex.tag_rename]]
    ## Regular expression to match on a tag name
    pattern = "^search_(\\w+)d$"
    ## Replacement expression defining the name of the new tag
    replacement = "${1}"
    ## If the new tag name already exists, you can either "overwrite" the
    ## existing one with the value of the renamed tag OR you can "keep"
    ## both the existing and source tag.
    # result_key = "keep"

  ## Rename metrics
  [[processors.regex.metric_rename]]
    ## Regular expression to match on an metric name
    pattern = "^search_(\\w+)d$"
    ## Replacement expression defining the new name of the metric
    replacement = "${1}"

Please note, you can use multiple tags, fields, tag_rename, field_rename and metric_rename sections in one processor. All of those are applied.

Tag and field value conversions

Conversions are only applied if a tag/field name matches the key which can contain glob statements such as * (asterix) and the pattern matches the tag/field value. For fields the field values has to be of type string to apply the conversion. If any of the given criteria does not apply the conversion is not applied to the metric.

The replacement option specifies the value of the resulting tag or field. It can reference capturing groups by index (e.g. ${1} being the first group) or by name (e.g. ${mygroup} being the group named mygroup).

By default, the currently processed tag or field is overwritten by the replacement. To create a new tag or field you can additionally specify the result_key option containing the new target tag or field name. In case the given tag or field already exists, its value is overwritten. For tags you might use the append flag to append the replacement value to an existing tag.

Batch processing using named groups

In tags and fields sections it is possible to use named groups to create multiple new tags or fields respectively. To do so, all capture groups have to be named in the pattern. Additional non-capturing ones or other expressions are allowed. Furthermore, neither replacement nor result_key can be set as the resulting tag/field name is the name of the group and the value corresponds to the group's content.

Tag and field name conversions

You can batch-rename tags and fields using the tag_rename and field_rename sections. Contrary to the tags and fields sections, the rename operates on the tag or field name, not its value.

A tag or field is renamed if the given pattern matches the name. The new name is specified via the replacement option. Optionally, the result_key can be set to either overwrite or keep (default) to control the behavior in case the target tag/field already exists. For overwrite the target tag/field is replaced by the source key. With this setting, the source tag/field is removed in any case. When using the keep setting (default), the target tag/field as well as the source is left unchanged and no renaming takes place.

Metric name conversions

Similar to the tag and field renaming, metric_rename section(s) can be used to rename metrics matching the given pattern. The resulting metric name is given via replacement option. If matching pattern the conversion is always applied. The result_key option has no effect on metric renaming and shall not be specified.

Tags

No tags are applied by this processor.

Example

In the following examples we are using this metric

nginx_requests,verb=GET,resp_code=200 request="/api/search/?category=plugins&q=regex&sort=asc",referrer="-",ident="-",http_version=1.1,agent="UserAgent",client_ip="127.0.0.1",auth="-",resp_bytes=270i 1519652321000000000

Explicit specification

[[processors.regex]]
  namepass = ["nginx_requests"]

  [[processors.regex.tags]]
    key = "resp_code"
    pattern = "^(\\d)\\d\\d$"
    replacement = "${1}xx"

  [[processors.regex.fields]]
    key = "request"
    pattern = "^/api(?P<method>/[\\w/]+)\\S*"
    replacement = "${method}"
    result_key = "method"

  [[processors.regex.fields]]
    key = "request"
    pattern = ".*category=(\\w+).*"
    replacement = "${1}"
    result_key = "search_category"

  [[processors.regex.field_rename]]
    pattern = "^client_(\\w+)$"
    replacement = "${1}"

will result in

-nginx_requests,verb=GET,resp_code=200 request="/api/search/?category=plugins&q=regex&sort=asc",referrer="-",ident="-",http_version=1.1,agent="UserAgent",client_ip="127.0.0.1",auth="-",resp_bytes=270i 1519652321000000000
+nginx_requests,verb=GET,resp_code=2xx request="/api/search/?category=plugins&q=regex&sort=asc",method="/search/",category="plugins",referrer="-",ident="-",http_version=1.1,agent="UserAgent",ip="127.0.0.1",auth="-",resp_bytes=270i 1519652321000000000

Appending

[[processors.regex]]
  namepass = ["nginx_requests"]

  [[processors.regex.tags]]
    key = "resp_code"
    pattern = '^2\d\d$'
    replacement = " OK"
    result_key = "verb"
    append = true

will result in

-nginx_requests,verb=GET,resp_code=200 request="/api/search/?category=plugins&q=regex&sort=asc",referrer="-",ident="-",http_version=1.1,agent="UserAgent",client_ip="127.0.0.1",auth="-",resp_bytes=270i 1519652321000000000
+nginx_requests,verb=GET\ OK,resp_code=200 request="/api/search/?category=plugins&q=regex&sort=asc",referrer="-",ident="-",http_version=1.1,agent="UserAgent",client_ip="127.0.0.1",auth="-",resp_bytes=270i 1519652321000000000

Named groups

[[processors.regex]]
  namepass = ["nginx_requests"]

  [[processors.regex.fields]]
    key = "request"
    pattern = '^/api/(?P<method>\w+)[/?].*category=(?P<category>\w+)&(?:.*)'

will result in

-nginx_requests,verb=GET,resp_code=200 request="/api/search/?category=plugins&q=regex&sort=asc",referrer="-",ident="-",http_version=1.1,agent="UserAgent",client_ip="127.0.0.1",auth="-",resp_bytes=270i 1519652321000000000
+nginx_requests,verb=GET,resp_code=200 request="/api/search/?category=plugins&q=regex&sort=asc",method="search",category="plugins",referrer="-",ident="-",http_version=1.1,agent="UserAgent",client_ip="127.0.0.1",auth="-",resp_bytes=270i 1519652321000000000

Metric renaming

[[processors.regex]]
  [[processors.regex.metric_rename]]
    pattern = '^(\w+)_.*$'
    replacement = "${1}"

will result in

-nginx_requests,verb=GET,resp_code=200 request="/api/search/?category=plugins&q=regex&sort=asc",referrer="-",ident="-",http_version=1.1,agent="UserAgent",client_ip="127.0.0.1",auth="-",resp_bytes=270i 1519652321000000000
+nginx,verb=GET,resp_code=200 request="/api/search/?category=plugins&q=regex&sort=asc",referrer="-",ident="-",http_version=1.1,agent="UserAgent",client_ip="127.0.0.1",auth="-",resp_bytes=270i 1519652321000000000