1.6.0 warns about missing dependencies when previous versions did not

[MarkEWaite]

With the inclusion of #220 in extra enforcer plugin 1.6.0, dependencies are reported as missing even though previous versions of the extra enforcer plugin did not warn about those dependencies and later use in the project do not report the dependencies as missing.

Background

Jenkins plugins (like the implied labels plugin) use a parent pom that includes the extra enforcer rules plugin. When plugins are upgraded to a parent pom version that uses extra enforcer rules 1.6.0, the plugin builds now received warnings like the following:

[WARNING] Missing:
----------
1) org.jenkins-ci.main:jenkins-test-harness:jar:1802.v9de0d87365d2

  Try downloading the file manually from the project website.

  Then, install it using the command:
      mvn install:install-file -DgroupId=org.jenkins-ci.main -DartifactId=jenkins-test-harness -Dversion=1802.v9de0d87365d2 -Dpackaging=jar -Dfile=/path/to/file

  Alternatively, if you host your own repository you can deploy the file there:
      mvn deploy:deploy-file -DgroupId=org.jenkins-ci.main -DartifactId=jenkins-test-harness -Dversion=1802.v9de0d87365d2 -Dpackaging=jar -Dfile=/path/to/file -Durl=[url] -DrepositoryId=[id]

  Path to dependency:
        1) org.jenkins-ci.main:jenkins-test-harness:jar:1802.v9de0d87365d2

----------
1 required artifact is missing.

for artifact:
  org.jenkins-ci.main:jenkins-test-harness:jar:1802.v9de0d87365d2

from the specified remote repositories:
  central (https://repo.maven.apache.org/maven2, releases=true, snapshots=false)
Path to dependency:
        1) org.jenkins-ci.main:jenkins-test-harness:jar:1802.v9de0d87365d2

The dependencies that are reported as unresolvable are then later resolved in the build process without issue.

Duplicate the issue

Duplicate the issue with the commands:

$ rm -rf implied-labels-plugin
$ git clone https://github.com/jenkinsci/implied-labels-plugin.git
$ cd implied-labels-plugin
$ echo '<settings></settings>' > settings.xml
$ mvn validate

Configuration change to avoid the issue

When I was seeing the issue, my ~/.m2/settings.xml file included the following mirror definition:

  <mirrors>
    <mirror>
      <id>repo.jenkins-ci.org</id>
      <url>https://repo.jenkins-ci.org/public/</url>
      <mirrorOf>m.g.o-public</mirrorOf>
    </mirror>
  </mirrors>

I can avoid the issue by changing my ~/.m2/settings.xml file to use the following mirror definition instead:

  <mirrors>
    <mirror>
      <id>repo.jenkins-ci.org</id>
      <url>https://repo.jenkins-ci.org/public/</url>
      <mirrorOf>*,!repo.jenkins-ci.org,!incrementals</mirrorOf>
    </mirror>
  </mirrors>

Other users have reported the same issue, including:

• @basil - Jenkins developers mailing list
• @martinda - Jenkins community forum
• @NotMyFault - Jenkins core pull request
• At least one other user in the Jenkins gitter channel

Expected results

I think that warnings about unresolvable dependencies in the extra enforcer rules should be consistent with the warnings in the rest of a maven build process.

[jglick]

Also reported as jenkinsci/jenkins#6875 (comment)

[jglick]

The artifact in question: https://repo.jenkins-ci.org/artifactory/public/org/jenkins-ci/main/jenkins-test-harness/1802.v9de0d87365d2/ (defined in repo itself as https://github.com/jenkinsci/implied-labels-plugin/blob/52f21e2d1fbcd6833a117165305931e1175e447b/pom.xml#L59)

[slawekjaranowski]

By the way mirrorOf must contains id of repositories which you want to mirror ...
https://maven.apache.org/guides/mini/guide-mirror-settings.html

In provided project I see only repositories with id: central, incrementals, repo.jenkins-ci.org, there is no repository with id m.g.o-public, so your mirror configuration can't work

With definition

<mirrorOf>*,!repo.jenkins-ci.org,!incrementals</mirrorOf>

you mirror central repositories by https://repo.jenkins-ci.org/public/

For resolving artifact only center was used - I fixed it.