maven settings.xml 中的存储库与 pluginRepositories

Question

I have the below settings.xml file in my ~/.m2/ folder:

<settings>
    <profiles>
        <profile>
            <id>my-repositories</id>
            <repositories>
                <repository>
                    <id>thirdparty-repository</id>
                    <name>Thirdparty repository</name>
                    <url>https://mynexus/repository/thirdparty/</url>
                </repository>
            </repositories>
            <pluginRepositories>
                <pluginRepository>
                    <id>thirdparty-plugin-repository</id>
                    <name>Thirdparty plugin repository</name>
                    <url>https://mynexus/repository/thirdparty/</url>
                </pluginRepository>
            </pluginRepositories>
        </profile>
    </profiles>
    <activeProfiles>
        <activeProfile>my-repositories</activeProfile>
    </activeProfiles>
</settings>

For both repositories the same nexus group repository is used:

https://mynexus/repository/thirdparty/

If I remove the first one: thirdparty-repository I get the below error:

Failed to read artifact descriptor for junit:junit:jar:4.8.2: Could not transfer artifact junit:junit:pom:4.8.2 from/to central (https://repo.maven.apache.org/maven2): sun.security.validator.ValidatorException: PKIX path building failed: sun.security.provider.certpath.SunCertPathBuilderException: unable to find valid certification path to requested target

Now If I re-enable it and instead remove the other one: thirdparty-plugin-repository I now get this error:

 Failed to read artifact descriptor for org.apache.maven.plugins:maven-clean-plugin:jar:2.5: Could not transfer artifact org.apache.maven.plugins:maven-clean-plugin:pom:2.5 from/to central (https://repo.maven.apache.org/maven2): sun.security.validator.ValidatorException: PKIX path building failed: sun.security.provider.certpath.SunCertPathBuilderException: unable to find valid certification path to requested target

Only when I have them both enabled at the same time it works.

Why do I need both repositories and pluginRepositories that points to the same nexus repository?

Answer 1

Suppose that you had defined a plugin with some dependencies. These dependencies will be searched in all of your <pluginRepository> definitions. Something like this:

<plugin>
   <groupId>org.liquibase</groupId>
   <artifactId>liquibase-maven-plugin</artifactId>
   <version>${liquibase.version}</version>
   <dependencies>
       <dependency>
          <groupId>io.herd.common</groupId>
          <artifactId>common-herd</artifactId>
          <version>${common.version}</version>
       </dependency>
   </dependencies>
</plugin>

Even if you have a <repository> defined which contains the common-herd artifact, Maven will not downloaded it unless you also have a <pluginRepository> containing it. And of course, the common-herd artifact can not be present inside the Maven Central Repository.

I had this problem a few months ago and Maven only downloaded the specific plugin dependency after I added a <pluginRepository>

Answer 2

I had a pb like this, idk if it will help but with this code in my POM.xml my nexus pb were resolved

    <distributionManagement>
    <repository>
        <id>nexus</id>
        <name>releases</name>
        <url>https://mynexus/repository/thirdparty/</url>
    </repository>
    <snapshotRepository>
        <id>nexus</id>
        <name>Snapshots</name>
        <url>https://mynexus/repository/thirdparty/</url>
    </snapshotRepository>
</distributionManagement>

and

        <!-- download artifacts from this repo -->
<repositories>
    <repository>
        <id>nexus</id>
        <name>Public</name>
        <url>https://mynexus/repository/thirdparty/</url>
        <releases>
            <enabled>true</enabled>
        </releases>

        <snapshots>
            <enabled>true</enabled>
        </snapshots>
    </repository>
</repositories>

hope it helped

Answer 3

In Nexus there is defined a public group which should contain all needed repositories and there should no need to configure this in your own pom nor in the settings.xml file. Only the public group of Nexus should be configured

The only thing you need is to change the url in mirror with your own location...

<settings>
  <mirrors>
    <mirror>
      <!--This sends everything else to /public -->
      <id>nexus</id>
      <mirrorOf>*</mirrorOf>
      <url>http://localhost:8081/repository/maven-public/</url>
    </mirror>
  </mirrors>
  <profiles>
    <profile>
      <id>nexus</id>
      <!--Enable snapshots for the built in central repo to direct -->
      <!--all requests to nexus via the mirror -->
      <repositories>
        <repository>
          <id>central</id>
          <url>http://central</url>
          <releases><enabled>true</enabled></releases>
          <snapshots><enabled>true</enabled></snapshots>
        </repository>
      </repositories>
     <pluginRepositories>
        <pluginRepository>
          <id>central</id>
          <url>http://central</url>
          <releases><enabled>true</enabled></releases>
          <snapshots><enabled>true</enabled></snapshots>
        </pluginRepository>
      </pluginRepositories>
    </profile>
  </profiles>
  <activeProfiles>
    <!--make the profile active all the time -->
    <activeProfile>nexus</activeProfile>
  </activeProfiles>
</settings>