Maven Could not resolve dependencies for hadoop project - maven

Question

I wanted to build the sample projects from hadoop book but I got "Could not resolve dependencies error".
Here is my Error during build:
[INFO] Building Chapter 2: MapReduce 3.0
[INFO] ------------------------------------------------------------------------
[WARNING] The POM for org.apache.hadoop:hadoop-core:jar:0.23.10 is missing, no dependency information available
[WARNING] The POM for org.apache.hadoop:hadoop-test:jar:0.23.10 is missing, no dependency information available
[INFO] ------------------------------------------------------------------------
[INFO] Reactor Summary:
[INFO]
[INFO] Chapter 2: MapReduce .............................. FAILURE [1.409s]
[INFO] Hadoop: The Definitive Guide, Example Code ........ SKIPPED
[INFO] ------------------------------------------------------------------------
[INFO] BUILD FAILURE
[INFO] ------------------------------------------------------------------------
[INFO] Total time: 1.819s
[INFO] Finished at: Wed May 14 12:19:14 EEST 2014
[INFO] Final Memory: 6M/67M
[INFO] ------------------------------------------------------------------------
[ERROR] Failed to execute goal on project ch02: Could not resolve dependencies for project com.hadoopbook:ch02:jar:3.0: The following artifacts could not be resolved: org.apache.hadoop:hadoop-core:jar:0.23.10, org.apache.hadoop:hadoop-test:jar:0.23.10: Failure to find org.apache.hadoop:hadoop-core:jar:0.23.10 in https://repository.apache.org/content/repositories/releases/ was cached in the local repository, resolution will not be reattempted until the update interval of apache.releases has elapsed or updates are forced -> [Help 1]
and here is my pom.xml for ch02 project
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/maven-v4_0_0.xsd">
<modelVersion>4.0.0</modelVersion>
<parent>
<groupId>com.hadoopbook</groupId>
<artifactId>hadoop-meta</artifactId>
<version>3.0</version>
<relativePath>../hadoop-meta/pom.xml</relativePath>
</parent>
<groupId>com.hadoopbook</groupId>
<artifactId>ch02</artifactId>
<packaging>jar</packaging>
<version>3.0</version>
<name>Chapter 2: MapReduce</name>
<dependencies>
<dependency>
<groupId>junit</groupId>
<artifactId>junit</artifactId>
</dependency>
<dependency>
<groupId>org.hamcrest</groupId>
<artifactId>hamcrest-all</artifactId>
</dependency>
</dependencies>
</project>
Any idea how can I build this code using maven and what the problem is ?
Thanks

Answer 1

What's happening is that Maven can't find the what it is looking for in the remote repository. So when it reaches out to Apache's Maven repository it's just not finding the resources for version 0.23.10 hadoop-test.
Particularly line #8 of the pom file in the question <relativePath>../hadoop-meta/pom.xml</relativePath> is directing Maven to look at hadoop-meta/pom.xml. On line #48 through #50 you'll see the specification for the hadoop-test repository:
<groupId>org.apache.hadoop</groupId>
<artifactId>hadoop-test</artifactId>
<version>${hadoop.version}</version>
That ${hadoop.version} is the value that you specify in your maven command, ie 0.23.10.
So then maven goes out to the Apache repo and looks for hadoop-test v0.23.10, which isn't present. So then Maven falls over.
Now if you used a version that is present in the hadoop-test, or if you altered the pom files so that hadoop-test isn't a dependency.

Answer 2

I had this problem as well, it turned out it was because of NetBeans adding something to my pom.xml file. Double check nothing was added since previous successful deployments.