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https://issues.apache.org/jira/browse/HADOOP-17088?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17198824#comment-17198824
]
Yushi Hayasaka commented on HADOOP-17088:
-----------------------------------------
Let me add an example.
Usually, when we want to load a Hadoop configuration file, we write like that:
* Main.java
{code:java}
package com.example.test;
import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.fs.Path;
import java.io.File;
public class Main {
public static void main(String[] args) {
String filePath = "/tmp/core-site.xml";
File file = new File(filePath);
Configuration configuration = new Configuration(false);
configuration.addResource(new Path(file.toURI()));
configuration.get("test");
}
}
{code}
* /tmp/core-site.xml
{code:xml}
<?xml version="1.0" encoding="UTF-8"?>
<?xml-stylesheet type="text/xsl" href="configuration.xsl"?>
<!--
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. See accompanying LICENSE file.
-->
<!-- Put site-specific property overrides in this file. -->
<configuration xmlns:xi="http://www.w3.org/2001/XInclude";>
<xi:include href="mountTable.xml" />
<property>
<name>fs.defaultFS</name>
<value>viewfs://clusterX</value>
</property>
</configuration>
{code}
* /tmp/mountTable.xml
{code:xml}
<configuration>
<property>
<name>fs.viewfs.mounttable.ClusterX.link./data</name>
<value>hdfs://nn1-clusterx.example.com:8020/data</value>
</property>
</configuration>
{code}
(I used [ViewFs
Guide|https://hadoop.apache.org/docs/r3.3.0/hadoop-project-dist/hadoop-hdfs/ViewFs.html]
example)
This example passes `Path` object to `addResource` parameter and the `Path` is
created from `URI` through `File.toURI()`. But actually it does not work
because of the error as I explain on the description of this ticket at first.
The example works well when we use `file.getPath()` (returns String) instead of
`toURI`.
Also, I think there is no difference with a security point of view because we
can load the XML file which is specified by `xi:include` and located outside of
the classpath when we load a configuration file using `file.getPath()`.
> Failed to load Xinclude files with relative path in case of loading conf via
> URI
> --------------------------------------------------------------------------------
>
> Key: HADOOP-17088
> URL: https://issues.apache.org/jira/browse/HADOOP-17088
> Project: Hadoop Common
> Issue Type: Bug
> Reporter: Yushi Hayasaka
> Priority: Major
> Labels: pull-request-available
> Time Spent: 40m
> Remaining Estimate: 0h
>
> When we create a configuration file, which load a external XML file with
> relative path, and try to load it via calling `Configuration.addResource`
> with `Path(URI)`, we got an error, which failed to load a external XML, after
> https://issues.apache.org/jira/browse/HADOOP-14216 is merged.
> {noformat}
> Exception in thread "main" java.lang.RuntimeException: java.io.IOException:
> Fetch fail on include for 'mountTable.xml' with no fallback while loading
> 'file:/opt/hadoop/etc/hadoop/core-site.xml'
> at
> org.apache.hadoop.conf.Configuration.loadResource(Configuration.java:3021)
> at
> org.apache.hadoop.conf.Configuration.loadResources(Configuration.java:2973)
> at
> org.apache.hadoop.conf.Configuration.getProps(Configuration.java:2848)
> at
> org.apache.hadoop.conf.Configuration.iterator(Configuration.java:2896)
> at com.company.test.Main.main(Main.java:29)
> Caused by: java.io.IOException: Fetch fail on include for 'mountTable.xml'
> with no fallback while loading 'file:/opt/hadoop/etc/hadoop/core-site.xml'
> at
> org.apache.hadoop.conf.Configuration$Parser.handleEndElement(Configuration.java:3271)
> at
> org.apache.hadoop.conf.Configuration$Parser.parseNext(Configuration.java:3331)
> at
> org.apache.hadoop.conf.Configuration$Parser.parse(Configuration.java:3114)
> at
> org.apache.hadoop.conf.Configuration.loadResource(Configuration.java:3007)
> ... 4 more
> {noformat}
> The cause is that the URI is passed as string to java.io.File constructor and
> File does not support the file URI, so my suggestion is trying to convert
> from string to URI at first.
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