azkaban.viewer.hdfs.HtmlFileViewer.java Source code

Introduction

Here is the source code for azkaban.viewer.hdfs.HtmlFileViewer.java

Source

/*
 * Copyright 2018 LinkedIn Corp.
 *
 * Licensed 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.
 *
 *
 * THIS IS AN EXPERIMENTAL FEATURE, USE WITH CAUTION.
 *
 * This viewer is aimed to support the rendering of very basic html files.
 * The content of a html file will be rendered inside an iframe on azkaban
 * web page to protect from possible malicious javascript code. It does not
 * support rendering local image files (e.g. image stored on hdfs), but it
 * does support showing images stored on remote network locations.
 *
 * In fact, not just images, but any data that is stored on HDFS are not
 * accessible from the html page, for example, css and js files. Everything
 * must either be self contained or referenced with internet location.
 * (e.g. jquery script hosted on google.com can be fetched, but jquery script
 * stored on local hdfs cannot)
 */

package azkaban.viewer.hdfs;

import java.io.IOException;
import java.io.OutputStream;
import java.util.EnumSet;
import java.util.HashSet;
import java.util.Set;
import org.apache.hadoop.fs.FileSystem;
import org.apache.hadoop.fs.Path;
import org.apache.hadoop.fs.permission.AccessControlException;
import org.apache.log4j.Logger;

public class HtmlFileViewer extends HdfsFileViewer {

    // only display the first 25M chars. it is used to prevent
    // showing/downloading gb of data
    private static final int BUFFER_LIMIT = 25000000;
    private static final String VIEWER_NAME = "Html";
    private static final Logger logger = Logger.getLogger(HtmlFileViewer.class);
    private final Set<String> acceptedSuffix = new HashSet<>();

    public HtmlFileViewer() {
        this.acceptedSuffix.add(".htm");
        this.acceptedSuffix.add(".html");
    }

    @Override
    public String getName() {
        return VIEWER_NAME;
    }

    @Override
    public Set<Capability> getCapabilities(final FileSystem fs, final Path path) throws AccessControlException {
        final String fileName = path.getName();
        final int pos = fileName.lastIndexOf('.');
        if (pos < 0) {
            return EnumSet.noneOf(Capability.class);
        }

        final String suffix = fileName.substring(pos).toLowerCase();
        if (this.acceptedSuffix.contains(suffix)) {
            return EnumSet.of(Capability.READ);
        } else {
            return EnumSet.noneOf(Capability.class);
        }
    }

    @Override
    public void displayFile(final FileSystem fs, final Path path, final OutputStream outputStream,
            final int startLine, final int endLine) throws IOException {

        if (logger.isDebugEnabled())
            logger.debug("read in uncompressed html file");

        // BUFFER_LIMIT is the only thing we care about, line limit is redundant and actually not
        // very useful for html files. Thus using Integer.MAX_VALUE to effectively remove the endLine limit.
        TextFileViewer.displayFileContent(fs, path, outputStream, startLine, Integer.MAX_VALUE, BUFFER_LIMIT);
    }

    @Override
    public ContentType getContentType() {
        return ContentType.HTML;
    }
}