org.apache.flume.source.http.HTTPSource 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.source.http;
import com.google.common.base.Preconditions;
import com.google.common.base.Throwables;
import org.apache.flume.ChannelException;
import org.apache.flume.Context;
import org.apache.flume.Event;
import org.apache.flume.EventDrivenSource;
import org.apache.flume.conf.Configurable;
import org.apache.flume.instrumentation.SourceCounter;
import org.apache.flume.source.AbstractSource;
import org.mortbay.jetty.Connector;
import org.mortbay.jetty.Server;
import org.mortbay.jetty.bio.SocketConnector;
import org.mortbay.jetty.servlet.ServletHolder;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;
import java.util.ArrayList;
import java.util.Collections;
import java.util.List;
import java.util.Map;
/**
* A source which accepts Flume Events by HTTP POST and GET. GET should be used
* for experimentation only. HTTP requests are converted into flume events by a
* pluggable "handler" which must implement the
* {@linkplain HTTPSourceHandler} interface. This handler takes a
* {@linkplain HttpServletRequest} and returns a list of flume events.
*
* The source accepts the following parameters: port: port to which
* the server should bind. Mandatory
handler: the class that
* deserializes a HttpServletRequest into a list of flume events. This class
* must implement HTTPSourceHandler. Default:
* {@linkplain JSONHandler}.
handler.* Any configuration
* to be passed to the handler.
*
* All events deserialized from one Http request are committed to the channel in
* one transaction, thus allowing for increased efficiency on channels like the
* file channel. If the handler throws an exception this source will return
* a HTTP status of 400. If the channel is full, or the source is unable to
* append events to the channel, the source will return a HTTP 503 - Temporarily
* unavailable status.
*
* A JSON handler which converts JSON objects to Flume events is provided.
*
*/
public class HTTPSource extends AbstractSource implements
EventDrivenSource, Configurable {
/*
* There are 2 ways of doing this:
* a. Have a static server instance and use connectors in each source
* which binds to the port defined for that source.
* b. Each source starts its own server instance, which binds to the source's
* port.
*
* b is more efficient than a because Jetty does not allow binding a
* servlet to a connector. So each request will need to go through each
* each of the handlers/servlet till the correct one is found.
*
*/
private static final Logger LOG = LoggerFactory.getLogger(HTTPSource.class);
private volatile Integer port;
private volatile Server srv;
private volatile String host;
private HTTPSourceHandler handler;
private SourceCounter sourceCounter;
@Override
public void configure(Context context) {
try {
port = context.getInteger(HTTPSourceConfigurationConstants.CONFIG_PORT);
host = context.getString(HTTPSourceConfigurationConstants.CONFIG_BIND,
HTTPSourceConfigurationConstants.DEFAULT_BIND);
checkHostAndPort();
String handlerClassName = context.getString(
HTTPSourceConfigurationConstants.CONFIG_HANDLER,
HTTPSourceConfigurationConstants.DEFAULT_HANDLER).trim();
@SuppressWarnings("unchecked")
Class clazz =
(Class)
Class.forName(handlerClassName);
handler = clazz.getDeclaredConstructor().newInstance();
//ref: http://docs.codehaus.org/display/JETTY/Embedding+Jetty
//ref: http://jetty.codehaus.org/jetty/jetty-6/apidocs/org/mortbay/jetty/servlet/Context.html
Map subProps =
context.getSubProperties(
HTTPSourceConfigurationConstants.CONFIG_HANDLER_PREFIX);
handler.configure(new Context(subProps));
} catch (ClassNotFoundException ex) {
LOG.error("Error while configuring HTTPSource. Exception follows.", ex);
Throwables.propagate(ex);
} catch (ClassCastException ex) {
LOG.error("Deserializer is not an instance of HTTPSourceHandler."
+ "Deserializer must implement HTTPSourceHandler.");
Throwables.propagate(ex);
} catch (Exception ex) {
LOG.error("Error configuring HTTPSource!", ex);
Throwables.propagate(ex);
}
if (sourceCounter == null) {
sourceCounter = new SourceCounter(getName());
}
}
private void checkHostAndPort() {
Preconditions.checkState(host != null && !host.isEmpty(),
"HTTPSource hostname specified is empty");
Preconditions.checkNotNull(port, "HTTPSource requires a port number to be"
+ " specified");
}
@Override
public void start() {
Preconditions.checkState(srv == null,
"Running HTTP Server found in source: " + getName()
+ " before I started one."
+ "Will not attempt to start.");
srv = new Server();
SocketConnector connector = new SocketConnector();
connector.setPort(port);
connector.setHost(host);
srv.setConnectors(new Connector[] { connector });
try {
org.mortbay.jetty.servlet.Context root =
new org.mortbay.jetty.servlet.Context(
srv, "/", org.mortbay.jetty.servlet.Context.SESSIONS);
root.addServlet(new ServletHolder(new FlumeHTTPServlet()), "/");
srv.start();
Preconditions.checkArgument(srv.getHandler().equals(root));
} catch (Exception ex) {
LOG.error("Error while starting HTTPSource. Exception follows.", ex);
Throwables.propagate(ex);
}
Preconditions.checkArgument(srv.isRunning());
sourceCounter.start();
super.start();
}
@Override
public void stop() {
try {
srv.stop();
srv.join();
srv = null;
} catch (Exception ex) {
LOG.error("Error while stopping HTTPSource. Exception follows.", ex);
}
sourceCounter.stop();
LOG.info("Http source {} stopped. Metrics: {}", getName(), sourceCounter);
}
private class FlumeHTTPServlet extends HttpServlet {
private static final long serialVersionUID = 4891924863218790344L;
@Override
public void doPost(HttpServletRequest request, HttpServletResponse response)
throws IOException {
List events = Collections.emptyList(); //create empty list
try {
events = handler.getEvents(request);
} catch (HTTPBadRequestException ex) {
LOG.warn("Received bad request from client. ", ex);
response.sendError(HttpServletResponse.SC_BAD_REQUEST,
"Bad request from client. "
+ ex.getMessage());
return;
} catch (Exception ex) {
LOG.warn("Deserializer threw unexpected exception. ", ex);
response.sendError(HttpServletResponse.SC_INTERNAL_SERVER_ERROR,
"Deserializer threw unexpected exception. "
+ ex.getMessage());
return;
}
sourceCounter.incrementAppendBatchReceivedCount();
sourceCounter.addToEventReceivedCount(events.size());
try {
getChannelProcessor().processEventBatch(events);
} catch (ChannelException ex) {
LOG.warn("Error appending event to channel. "
+ "Channel might be full. Consider increasing the channel "
+ "capacity or make sure the sinks perform faster.", ex);
response.sendError(HttpServletResponse.SC_SERVICE_UNAVAILABLE,
"Error appending event to channel. Channel might be full."
+ ex.getMessage());
return;
} catch (Exception ex) {
LOG.warn("Unexpected error appending event to channel. ", ex);
response.sendError(HttpServletResponse.SC_INTERNAL_SERVER_ERROR,
"Unexpected error while appending event to channel. "
+ ex.getMessage());
return;
}
response.setCharacterEncoding(request.getCharacterEncoding());
response.setStatus(HttpServletResponse.SC_OK);
response.flushBuffer();
sourceCounter.incrementAppendBatchAcceptedCount();
sourceCounter.addToEventAcceptedCount(events.size());
}
@Override
public void doGet(HttpServletRequest request, HttpServletResponse response)
throws IOException {
doPost(request, response);
}
}
}