Hello

I love detailed explanations, so here's one.

First, an observation. If you check
https://repository.apache.org/content/groups/snapshots-group/org/apache/karaf/webconsole/org.apache.karaf.webconsole.http/4.2.0-SNAPSHOT/maven-metadata.xml,
you'll see this metadata declares latest SNAPSHOT version to be
"4.2.0-20170713.142530-162". But if you try to actually fetch this version
(that's what Aether is doing), you'll get HTTP 404, because there's *no
such version* - there's "4.2.0-20170713.142529-162" - 1 *second*
difference, but very important - this SNAPSHOT is *not resolvable*.

I started wondering about Nexus problems, about maven-deploy-plugin bugs,
but then I run this under debugger. I didn't notice this problem when using
Maven 3.5.0, but it failed under 3.3.9 (that's the version used by Jenkins).

Another worrying sign was this log:

[INFO] --- maven-deploy-plugin:2.8.2:deploy (default-deploy) @
org.apache.karaf.features.core ---
...
[INFO] Downloading:
http://localhost:8081/nexus/content/repositories/snapshots/org/apache/karaf/features/org.apache.karaf.features.core/maven-metadata.xml
[INFO] Downloaded:
http://localhost:8081/nexus/content/repositories/snapshots/org/apache/karaf/features/org.apache.karaf.features.core/maven-metadata.xml
(315 B at 4.6 KB/sec)
[INFO] Downloading:
http://localhost:8081/nexus/content/repositories/snapshots/org/apache/karaf/features/org.apache.karaf.features.core/maven-metadata.xml
[INFO] Downloaded:
http://localhost:8081/nexus/content/repositories/snapshots/org/apache/karaf/features/org.apache.karaf.features.core/maven-metadata.xml
(315 B at 10.6 KB/sec)
[INFO] Uploading:
http://localhost:8081/nexus/content/repositories/snapshots/org/apache/karaf/features/org.apache.karaf.features.core/4.2.0-SNAPSHOT/maven-metadata.xml
[INFO] Uploaded:
http://localhost:8081/nexus/content/repositories/snapshots/org/apache/karaf/features/org.apache.karaf.features.core/4.2.0-SNAPSHOT/maven-metadata.xml
(805 B at 31.4 KB/sec)
[INFO] Uploading:
http://localhost:8081/nexus/content/repositories/snapshots/org/apache/karaf/features/org.apache.karaf.features.core/4.2.0-SNAPSHOT/maven-metadata.xml
[INFO] Uploaded:
http://localhost:8081/nexus/content/repositories/snapshots/org/apache/karaf/features/org.apache.karaf.features.core/4.2.0-SNAPSHOT/maven-metadata.xml
(805 B at 30.2 KB/sec)
...

It looked as duplicate metadata upload. I was fooled by reading
maven-deploy-plugin source code, because it actually may upload metadata
multiple times (in case of attached artifacts).

But then, under debugger I saw this:

generators = {java.util.ArrayList@9874}  size = 4
 0 =
{org.apache.maven.repository.internal.RemoteSnapshotMetadataGenerator@9881}
  snapshots: java.util.Map  = {java.util.LinkedHashMap@9890}  size = 0
  legacyFormat: boolean  = false
 1 =
{org.apache.maven.repository.internal.RemoteSnapshotMetadataGenerator@9882}
  snapshots: java.util.Map  = {java.util.LinkedHashMap@9889}  size = 0
  legacyFormat: boolean  = false
 2 = {org.apache.maven.repository.internal.VersionsMetadataGenerator@9883}
  versions: java.util.Map  = {java.util.LinkedHashMap@9887}  size = 0
  processedVersions: java.util.Map  = {java.util.LinkedHashMap@9888}  size
= 0
 3 = {org.apache.maven.repository.internal.VersionsMetadataGenerator@9884}
  versions: java.util.Map  = {java.util.LinkedHashMap@9885}  size = 0
  processedVersions: java.util.Map  = {java.util.LinkedHashMap@9886}  size
= 0

which means that
org.eclipse.aether.internal.impl.DefaultDeployer#getMetadataGenerators()
returned/used too many generators. And I found that *this is the root
problem* - we have two instances of RemoteSnapshotMetadataGenerator and
both may transform "SNAPSHOT" version to two different timestamped versions
- then artifact is uploaded *once* (with first timestamped version) and
then metadata is uploaded twice - first time with correct version and then
with 1-second later version...

Why? Why duplicate generators? The problem is _class realm_ of ...
org.apache.karaf.tooling:karaf-services-maven-plugin when running on Maven
3.3.9. maven-aether-provider-3.3.9.jar declares
(META-INF/plexus/components.xml):
    <component>
      <role>org.eclipse.aether.impl.MetadataGeneratorFactory</role>
      <role-hint>snapshot</role-hint>

<implementation>org.apache.maven.repository.internal.SnapshotMetadataGeneratorFactory</implementation>
      <description />
      <isolated-realm>false</isolated-realm>
    </component>

and maven-resolver-provider-3.5.0.jar (direct dependency of
karaf-services-maven-plugin) has (META-INF/plexus/components.xml):
    <component>
      <role>org.eclipse.aether.impl.MetadataGeneratorFactory</role>
      <role-hint>snapshot</role-hint>

<implementation>org.apache.maven.repository.internal.SnapshotMetadataGeneratorFactory</implementation>
      <description />
      <isolated-realm>false</isolated-realm>
    </component>

Even if these declaration from different deps lead to single Class of
org.apache.maven.repository.internal.SnapshotMetadataGeneratorFactory (from
maven-aether-provider-3.3.9.jar), we still have TWO instances of such class.

I won't provide fix yet, I'm just letting you know that this dependency
list is wrong:
https://github.com/apache/karaf/blob/master/tooling/karaf-services-maven-plugin/pom.xml#L41-L143
- we should not mix Eclipse and Sonatype versions of Aether and we should
not depend on maven-resolver-provider. We can't easily exclude deps for
Maven plugins (like we can for dependencies) though.

I'll try to look at this issue tomorrow.

best regards
Grzegorz Grzybek

2017-07-13 13:49 GMT+02:00 Jean-Baptiste Onofré <[email protected]>:

> Just a quick update: master is now ok. I'm fixing the other Jenkins jobs.
>
> Regards
> JB
>
>
> On 07/12/2017 01:53 PM, Jean-Baptiste Onofré wrote:
>
>> Hi guys,
>>
>> FYI, a recent commit (I'm suspecting on the karaf-maven-plugin) broke the
>> build (on master). It seems that the itests fail to resolve the artifacts.
>> For instance:
>>
>> Error downloading mvn:org.apache.karaf.jms/org.a
>> pache.karaf.jms.pool/4.2.0-SNAPSHOT
>>
>> org.apache.karaf.features.internal.util.MultiException: Error:
>>      Error downloading mvn:org.apache.karaf.jms/org.a
>> pache.karaf.jms.pool/4.2.0-SNAPSHOT
>>      at org.apache.karaf.features.internal.download.impl.MavenDownlo
>> adManager$MavenDownloader.<init>(MavenDownloadManager.java:86)
>>      at org.apache.karaf.features.internal.download.impl.MavenDownlo
>> adManager.createDownloader(MavenDownloadManager.java:72)
>>
>> I'm checking the other builds too.
>>
>> My plan is to fix all building issues asap.
>>
>> Regards
>> JB
>>
>
> --
> Jean-Baptiste Onofré
> [email protected]
> http://blog.nanthrax.net
> Talend - http://www.talend.com
>

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