Grok

Since Camel 3.0

This component provides dataformat for processing inputs with grok patterns. Grok patterns are used to process unstructured data into structured objects - List<Map<String, Object>>.

This component is based on the Java Grok library

Maven users will need to add the following dependency to their pom.xml for this component:

<dependency>
    <groupId>org.apache.camel</groupId>
    <artifactId>camel-grok</artifactId>
    <version>x.x.x</version>
    <!-- use the same version as your Camel core version -->
</dependency>

Usage

Extract all IP addresses from input

  • Java

  • XML

  • YAML

from("direct:in")
    .unmarshal().grok("%{IP:ip}")
    .to("log:out");
<route>
  <from uri="direct:in"/>
  <unmarshal><grok pattern="%{IP:ip}"/></unmarshal>
  <to uri="log:out"/>
</route>
- route:
    from:
      uri: direct:in
      steps:
        - unmarshal:
            grok:
              pattern: "%{IP:ip}"
        - to:
            uri: log:out
Parse Apache logs and process only 4xx responses

  • Java

  • XML

  • YAML

from("file://apacheLogs")
    .unmarshal().grok("%{COMBINEDAPACHELOG")
    .split(body()).filter(simple("${body[response]} starts with '4'"))
    .to("log:4xx");
<route>
  <from uri="file://apacheLogs"/>
  <unmarshal><grok pattern="%{COMBINEDAPACHELOG"/></unmarshal>
  <split>
    <simple>${body}</simple>
    <filter>
      <simple>${body[response]} starts with '4'</simple>
      <to uri="log:4xx"/>
    </filter>
  </split>
</route>
- route:
    from:
      uri: file://apacheLogs
      steps:
        - unmarshal:
            grok:
              pattern: "%{COMBINEDAPACHELOG"
        - split:
            simple: "${body}"
            steps:
              - filter:
                  simple: "${body[response]} starts with '4'"
                  steps:
                    - to:
                        uri: log:4xx

Preregistered patterns

This component comes with preregistered patterns, which are based on Logstash patterns. All Java Grok Default Patterns are preregistered and as such could be used without manual registration.

Custom patterns

Camel Grok DataFormat supports plugable patterns, which are auto loaded from Camel Registry. You can register patterns with Java DSL and Spring DSL:

Java-only: registering a custom Grok pattern
bindToRegistry("myCustomPatternBean", new GrokPattern("FOOBAR", "foo|bar"));

from("direct:in")
    .unmarshal().grok("%{FOOBAR:fooBar}")
    .to("log:out");

In Spring XML, you register the custom pattern as a bean:

XML-only: Spring XML bean registration
<beans>
    <bean id="myCustomPatternBean" class="org.apache.camel.component.grok.GrokPattern">
        <constructor-arg value="FOOBAR"/>
        <constructor-arg value="foo|bar"/>
    </bean>
</beans>

Grok Data format Options

The Grok dataformat supports 4 options, which are listed below.

Name Default Java Type Description

pattern (common)

String

The grok pattern to match lines of input.

flattened (common)

false

Boolean

Whether to use flattened mode. In flattened mode an exception is thrown when there are multiple pattern matches with the same key.

allowMultipleMatchesPerLine (common)

true

Boolean

Whether to allow multiple matches per line. If false, every line of input is matched for the pattern only once. Otherwise the line can be scanned multiple times when a non-terminal pattern is used.

namedOnly (common)

false

Boolean

Whether to capture named expressions only or not (i.e. %\{IP:ip} but not ${IP}).
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