org.apache.flume.interceptor.StaticInterceptor Maven / Gradle / Ivy
/**
* Licensed to the Apache Software Foundation (ASF) under one
* or more contributor license agreements. See the NOTICE file
* distributed with this work for additional information
* regarding copyright ownership. The ASF licenses this file
* to you under the Apache License, Version 2.0 (the
* "License"); you may not use this file except in compliance
* with the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.apache.flume.interceptor;
import java.util.List;
import java.util.Map;
import org.apache.flume.Context;
import org.apache.flume.Event;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import static org.apache.flume.interceptor.StaticInterceptor.Constants.*;
/**
* Interceptor class that appends a static, pre-configured header to all events.
*
* Properties:
*
* key: Key to use in static header insertion.
* (default is "key")
*
* value: Value to use in static header insertion.
* (default is "value")
*
* preserveExisting: Whether to preserve an existing value for 'key'
* (default is true)
*
* Sample config:
*
*
* agent.sources.r1.channels = c1
* agent.sources.r1.type = SEQ
* agent.sources.r1.interceptors = i1
* agent.sources.r1.interceptors.i1.type = static
* agent.sources.r1.interceptors.i1.preserveExisting = false
* agent.sources.r1.interceptors.i1.key = datacenter
* agent.sources.r1.interceptors.i1.value= NYC_01
*
*
*/
public class StaticInterceptor implements Interceptor {
private static final Logger logger = LoggerFactory
.getLogger(StaticInterceptor.class);
private final boolean preserveExisting;
private final String key;
private final String value;
/**
* Only {@link HostInterceptor.Builder} can build me
*/
private StaticInterceptor(boolean preserveExisting, String key,
String value) {
this.preserveExisting = preserveExisting;
this.key = key;
this.value = value;
}
@Override
public void initialize() {
// no-op
}
/**
* Modifies events in-place.
*/
@Override
public Event intercept(Event event) {
Map headers = event.getHeaders();
if (preserveExisting && headers.containsKey(key)) {
return event;
}
headers.put(key, value);
return event;
}
/**
* Delegates to {@link #intercept(Event)} in a loop.
* @param events
* @return
*/
@Override
public List intercept(List events) {
for (Event event : events) {
intercept(event);
}
return events;
}
@Override
public void close() {
// no-op
}
/**
* Builder which builds new instance of the StaticInterceptor.
*/
public static class Builder implements Interceptor.Builder {
private boolean preserveExisting;
private String key;
private String value;
@Override
public void configure(Context context) {
preserveExisting = context.getBoolean(PRESERVE, PRESERVE_DEFAULT);
key = context.getString(KEY, KEY_DEFAULT);
value = context.getString(VALUE, VALUE_DEFAULT);
}
@Override
public Interceptor build() {
logger.info(String.format(
"Creating StaticInterceptor: preserveExisting=%s,key=%s,value=%s",
preserveExisting, key, value));
return new StaticInterceptor(preserveExisting, key, value);
}
}
public static class Constants {
public static final String KEY = "key";
public static final String KEY_DEFAULT = "key";
public static final String VALUE = "value";
public static final String VALUE_DEFAULT = "value";
public static final String PRESERVE = "preserveExisting";
public static final boolean PRESERVE_DEFAULT = true;
}
}