The mutate filter allows you to perform general mutations on fields. You can rename, remove, replace, and modify fields in your events.
TODO(sissel): Support regexp replacements like String#gsub ?
filter {
mutate {
add_field => ... # hash (optional), default: {}
add_tag => ... # array (optional), default: []
convert => ... # hash (optional)
gsub => ... # array (optional)
join => ... # hash (optional)
lowercase => ... # array (optional)
merge => ... # hash (optional)
remove_field => ... # array (optional), default: []
remove_tag => ... # array (optional), default: []
rename => ... # hash (optional)
replace => ... # hash (optional)
split => ... # hash (optional)
strip => ... # array (optional)
update => ... # hash (optional)
uppercase => ... # array (optional)
}
}
If this filter is successful, add any arbitrary fields to this event. Field names can be dynamic and include parts of the event using the %{field} Example:
filter {
mutate {
add_field => { "foo_%{somefield}" => "Hello world, from %{host}" }
}
}
# You can also add multiple fields at once:
filter {
mutate {
add_field => {
"foo_%{somefield}" => "Hello world, from %{host}"
"new_field" => "new_static_value"
}
}
}
If the event has field “somefield” == “hello” this filter, on success, would add field “foo_hello” if it is present, with the value above and the %{host} piece replaced with that value from the event. The second example would also add a hardcoded field.
If this filter is successful, add arbitrary tags to the event. Tags can be dynamic and include parts of the event using the %{field} syntax. Example:
filter {
mutate {
add_tag => [ "foo_%{somefield}" ]
}
}
# You can also add multiple tags at once:
filter {
mutate {
add_tag => [ "foo_%{somefield}", "taggedy_tag"]
}
}
If the event has field “somefield” == “hello” this filter, on success, would add a tag “foo_hello” (and the second example would of course add a “taggedy_tag” tag).
Convert a field’s value to a different type, like turning a string to an integer. If the field value is an array, all members will be converted. If the field is a hash, no action will be taken.
Valid conversion targets are: integer, float, string.
Example:
filter {
mutate {
convert => [ "fieldname", "integer" ]
}
}
Only handle events without all/any (controlled by exclude_any config option) of these tags. Optional.
Convert a string field by applying a regular expression and a replacement. If the field is not a string, no action will be taken.
This configuration takes an array consisting of 3 elements per field/substitution.
Be aware of escaping any backslash in the config file.
Example:
filter {
mutate {
gsub => [
# replace all forward slashes with underscore
"fieldname", "/", "_",
# replace backslashes, question marks, hashes, and minuses with
# dot
"fieldname2", "[\\?#-]", "."
]
}
}
Join an array with a separator character. Does nothing on non-array fields.
Example:
filter { mutate { join => [“fieldname”, “,”] } }
Convert a string to its lowercase equivalent.
Example:
filter {
mutate {
lowercase => [ "fieldname" ]
}
}
Merge two fields of arrays or hashes. String fields will be automatically be converted into an array, so: array + string will work string + string will result in an 2 entry array in dest_field array and hash will not work
Example:
filter {
mutate {
merge => ["dest_field", "added_field"]
}
}
Remove one or more fields.
Example:
filter {
mutate {
remove => [ "client" ] # Removes the 'client' field
}
}
This option is deprecated, instead use remove_field option available in all filters.
If this filter is successful, remove arbitrary fields from this event. Fields names can be dynamic and include parts of the event using the %{field} Example:
filter {
mutate {
remove_field => [ "foo_%{somefield}" ]
}
}
# You can also remove multiple fields at once:
filter {
mutate {
remove_field => [ "foo_%{somefield}" "my_extraneous_field" ]
}
}
If the event has field “somefield” == “hello” this filter, on success, would remove the field with name “foo_hello” if it is present. The second example would remove an additional, non-dynamic field.
If this filter is successful, remove arbitrary tags from the event. Tags can be dynamic and include parts of the event using the %{field} syntax. Example:
filter {
mutate {
remove_tag => [ "foo_%{somefield}" ]
}
}
# You can also remove multiple tags at once:
filter {
mutate {
remove_tag => [ "foo_%{somefield}", "sad_unwanted_tag"]
}
}
If the event has field “somefield” == “hello” this filter, on success, would remove the tag “foo_hello” if it is present. The second example would remove a sad, unwanted tag as well.
Rename one or more fields.
Example:
filter {
mutate {
# Renames the 'HOSTORIP' field to 'client_ip'
rename => [ "HOSTORIP", "client_ip" ]
}
}
Replace a field with a new value. The new value can include %{foo} strings to help you build a new value from other parts of the event.
Example:
filter {
mutate {
replace => [ "message", "%{source_host}: My new message" ]
}
}
Split a field to an array using a separator character. Only works on string fields.
Example:
filter {
mutate {
split => ["fieldname", ","]
}
}
Strip whitespace from field. NOTE: this only works on leading and trailing whitespace.
Example:
filter {
mutate {
strip => ["field1", "field2"]
}
}
Only handle events with all/any (controlled by include_any config option) of these tags. Optional.
Note that all of the specified routing options (type,tags.exclude_tags,include_fields,exclude_fields) must be met in order for the event to be handled by the filter. The type to act on. If a type is given, then this filter will only act on messages with the same type. See any input plugin’s “type” attribute for more. Optional.
Update an existing field with a new value. If the field does not exist, then no action will be taken.
Example:
filter {
mutate {
update => [ "sample", "My new message" ]
}
}
Convert a string to its uppercase equivalent.
Example:
filter {
mutate {
uppercase => [ "fieldname" ]
}
}