Maven downloads artifacts that are defined in two locations:

  • Artifact repositories defined in a pom.xml file of the project. Configuring repositories in pom.xml is not specific to Eclipse Che. For more information, see the Maven documentation about the POM.

  • Artifact repositories defined in a settings.xml file. By default, settings.xml is located at `~/.m2/settings.xml.

Defining repositories in settings.xml

To specify your own artifact repositories at example.server.org, use the settings.xml file. To do that, ensure, that settings.xml is present in all the containers that use Maven tools, in particular the Maven container and the Java plug-in container.

By default, settings.xml is located at the <home dir>/.m2 directory. Because the user home directory is not on a persistent volume, you must re-create the file each time you restart the workspace. This is a known issue, see the issue on GitHub.

A workaround is to make the file persist between the restarts of the workspace, create a directory /projects/maven/.m2, and move the settings.xml file in it. Then set the value of the user.home Java system property to /projects/maven in all your Maven containers.

Procedure

  1. Configure your settings.xml file to use artifact repositories at example.server.org:

    <settings>
  <profiles>
    <profile>
      <id>my-nexus</id>
      <pluginRepositories>
        <pluginRepository>
           <id>my-nexus-snapshots</id>
           <releases>
             <enabled>false</enabled>
           </releases>
           <snapshots>
             <enabled>true</enabled>
           </snapshots>
           <url>http://example.server.org/repository/maven-snapshots/</url>
        </pluginRepository>
        <pluginRepository>
           <id>my-nexus-releases</id>
           <releases>
             <enabled>true</enabled>
           </releases>
           <snapshots>
             <enabled>false</enabled>
           </snapshots>
           <url>http://example.server.org/repository/maven-releases/</url>
        </pluginRepository>
      </pluginRepositories>
      <repositories>
        <repository>
           <id>my-nexus-snapshots</id>
           <releases>
             <enabled>false</enabled>
           </releases>
           <snapshots>
             <enabled>true</enabled>
           </snapshots>
           <url>http://example.server.org/repository/maven-snapshots/</url>
        </repository>
        <repository>
           <id>my-nexus-releases</id>
           <releases>
             <enabled>true</enabled>
           </releases>
           <snapshots>
             <enabled>false</enabled>
           </snapshots>
           <url>http://example.server.org/repository/maven-releases/</url>
        </repository>
      </repositories>
    </profile>
  </profiles>
  <activeProfiles>
    <activeProfile>my-nexus</activeProfile>
  </activeProfiles>
</settings>

  2. Configure the devfile to use the /projects/maven value for the user.home Java system property.

    1. For the Java plug-in container, configure the language server start arguments preference:

      components:
  - id: redhat/java11/latest
    type: chePlugin
    preferences:
      java.jdt.ls.vmargs: >-
        -noverify -Xmx1G -XX:+UseG1GC -XX:+UseStringDeduplication
        -Duser.home=/projects/maven

    2. For the Maven container, configure the MAVEN_OPTS environment variable:

      mountSources: true
    alias: maven
    type: dockerimage
    ...
    env:
       -name: MAVEN_OPTS
        value: >-
          -Duser.home=/projects/maven

Using self-signed certificates in Java projects

Internal artifact repositories often do not have a self-signed (SSL) certificate signed by an authority that is trusted by default in Java. They are usually signed by an internal company authority or are self-signed. Configure your tools to accept these certificates by adding them to the Java truststore.

Procedure

  1. Obtain a server certificate file from the repository server. It is often a file named tls.crt.

    1. Create a Java truststore file:

      $ keytool -import -file tls.crt -alias nexus -keystore truststore.jks -storepass changeit

Trust this certificate? [no]:  yes
Certificate was added to keystore
Owner: CN=example.com
Issuer: CN=example.com
Serial number: 80ca0f6980c6019a
Valid from: Thu Feb 06 11:00:29 CET 2020 until: Fri Feb 05 11:00:29 CET 2021
Certificate fingerprints:
     MD5:  88:3C:EC:E1:BE:57:DD:9D:46:36:8E:DD:BF:14:04:22
     SHA1: 08:D8:79:D3:F8:6B:5C:3D:71:AA:23:CA:72:01:47:BD:9D:91:0A:AD
     SHA256: 5C:BB:66:81:44:D2:50:EE:EB:CE:D6:15:7E:63:E1:9A:71:EA:58:3F:14:01:15:4E:68:5D:71:0A:A0:31:33:29
Signature algorithm name: SHA256withRSA
Subject Public Key Algorithm: 4096-bit RSA key
Version: 3

Extensions:

#1: ObjectId: 2.5.29.17 Criticality=false
SubjectAlternativeName [
  DNSName: *.apps.example.com
]

Trust this certificate? [no]:  yes
Certificate was added to keystore

    2. Upload the truststore file to /projects/maven/truststore.jks to make it available for all containers.

  2. Add the truststore file.

    • In the Maven container:

      1. Add the javax.net.ssl system property to the MAVEN_OPTS environment variable:

          - mountSources: true
    alias: maven
    type: dockerimage
    ...
    env:
       -name: MAVEN_OPTS
        value: >-
          -Duser.home=/projects/maven -Djavax.net.ssl.trustStore=/projects/truststore.jks

      2. Restart the workspace.

    • In the Java plug-in container:

      In the devfile, add the javax.net.ssl system property for the Java language server:

      components:
  - id: redhat/java11/latest
    type: chePlugin
    preferences:
      java.jdt.ls.vmargs: >-
        -noverify -Xmx1G -XX:+UseG1GC -XX:+UseStringDeduplication
        -Duser.home=/projects/maven
        -Djavax.net.ssl.trustStore=/projects/truststore.jks
[...]
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