Grep

The Grep Filter plugin allows to match or exclude specific records based in regular expression patterns.

Configuration Parameters

The plugin supports the following configuration parameters:

Key

Value Format

Description

Regex

FIELD REGEX

Keep records which field matches the regular expression.

Exclude

FIELD REGEX

Exclude records which field matches the regular expression.

Getting Started

In order to start filtering records, you can run the filter from the command line or through the configuration file. The following example assumes that you have a file called lines.txt with the following content

aaa
aab
bbb
ccc
ddd
eee
fff
ggg

Command Line

Note: using the command line mode need special attention to quote the regular expressions properly. It's suggested to use a configuration file.

The following command will load the tail plugin and read the content of lines.txt file. Then the grep filter will apply a regular expression rule over the log field (created by tail plugin) and only pass the records which field value starts with aa:

$ bin/fluent-bit -i tail -p 'path=lines.txt' -F grep -p 'regex=log aa' -m '*' -o stdout

Configuration File

[INPUT]
Name tail
Path lines.txt
[FILTER]
Name grep
Match *
Regex log aa
[OUTPUT]
Name stdout
Match *

The filter allows to use multiple rules which are applied in order, you can have many Regex and Exclude entries as required.

Nested fields example

Currently nested fields are not supported. If you have records in the following format

{
"kubernetes": {
"pod_name": "myapp-0",
"namespace_name": "default",
"pod_id": "216cd7ae-1c7e-11e8-bb40-000c298df552",
"labels": {
"app": "myapp"
},
"host": "minikube",
"container_name": "myapp",
"docker_id": "370face382c7603fdd309d8c6aaaf434fd98b92421ce7c7c8aafe7697d4aa362"
}
}

and if you want to exclude records that match given nested field (for example kubernetes.labels.app), you could use combination of nest and grep filters. Here is an example that will exclude records that match kubernetes.labels.app: myapp:

[FILTER]
Name nest
Match *
Operation lift
Nested_under kubernetes
[FILTER]
Name nest
Match *
Operation lift
Nested_under labels
[FILTER]
Name grep
Match *
Exclude app myapp