Building a Maven p2 repo with features

[reckart]

This is a kind of a follow-up to #925 attempting to build the update site as a Maven update site.

I am trying to adapt the approach taken by the Jetty team and have added this tycho-p2-repository-plugin configuration to my update site Maven module:

      <plugin>
        <groupId>org.eclipse.tycho</groupId>
        <artifactId>tycho-p2-repository-plugin</artifactId>
        <version>${tycho-version}</version>
        <executions>
          <execution>
            <id>maven-p2-site</id>
            <phase>prepare-package</phase>
            <goals>
              <goal>assemble-maven-repository</goal>
            </goals>
            <configuration>
              <includeReactor>true</includeReactor>
              <includeDependencies>false</includeDependencies>
            </configuration>
          </execution>
        </executions>
      </plugin>

However, there are two problems with that:

1. it only picks up the OSGi bundles from the reactor, not the feature modules (that are built using Tycho)
2. it only works if building the entire reactor, not when only building the update site module.

So I tried adjusting to adding the features as dependencies and including dependencies in the build:

  <dependencies>
    <dependency>
      <groupId>org.apache.uima</groupId>
      <artifactId>org.apache.uima.runtime.feature.group</artifactId>
      <version>3.3.0-SNAPSHOT</version>
    </dependency>
    <dependency>
      <groupId>org.apache.uima</groupId>
      <artifactId>org.apache.uima.tools.feature.group</artifactId>
      <version>3.3.0-SNAPSHOT</version>
    </dependency>
  </dependencies>

      <plugin>
        <groupId>org.eclipse.tycho</groupId>
        <artifactId>tycho-p2-repository-plugin</artifactId>
        <version>${tycho-version}</version>
        <executions>
          <execution>
            <id>maven-p2-site</id>
            <phase>prepare-package</phase>
            <goals>
              <goal>assemble-maven-repository</goal>
            </goals>
            <configuration>
              <includeReactor>false</includeReactor>
              <includeDependencies>true</includeDependencies>
            </configuration>
          </execution>
        </executions>
      </plugin>

But that yields an empty update site again:

% unzip -l uimaj-eclipse-update-site/target/p2-site.zip
Archive:  uimaj-eclipse-update-site/target/p2-site.zip
  Length      Date    Time    Name
---------  ---------- -----   ----
      403  05-04-2022 12:11   content.xml
      610  05-04-2022 12:11   artifacts.xml
---------                     -------
     1013                     2 files

Also, the uimaj-eclipse-update-site contains a category.xml file, but it seems to be ignored, although I can see it being added via the -categoryDefinition to the org.eclipse.tycho.p2.tools.publisher.TychoFeaturesAndBundlesPublisher when build with -X.

I can see an odd error message printed to stderr, but it doesn't tell me which file is the problem:

    Generating metadata for ..
    Generation completed with success [0 seconds].
>>  [Fatal Error] :1:1: Premature end of file.
    [INFO] Building zip: .../uimaj-eclipse-update-site/target/p2-site.zip

[laeubi]

1. it only picks up the OSGi bundles from the reactor, not the feature modules (that are built using Tycho)

I think features are not supported right now neverless.

2. it only works if building the entire reactor, not when only building the update site module.

That is intentional as the goal for jetty is to include everything currently build without any further configuration, if you only build the site, then there is nothing to include (how should the mojo know?)

So I tried adjusting to adding the features as dependencies and including dependencies in the build

That is the correct approach, but will only work for bundles right now, so instead of a feature you need to add a dependency to all the bundles that feature includes.

By the way, this feature was specifically crafted to be used in "non tycho" cases, it does not work well if you try to mix things here, see

• Support maven-p2-site generation as part of regular tycho build #436

[reckart]

Well, an Update Site containing only metadata should hopefully not be so large that it matters?

[laeubi]

I checked this and mvn protocol support was added back in Nov 25, 2020 so ther must be something broken or wrong URL used somewhere...

[laeubi]

Well, an Update Site containing only metadata should hopefully not be so large that it matters?

Sure, just wanted to note that in case one uses that for larger ones, anyways inside it is still using mvn urls so actually it should work at from the very beginning without any hacks.

[reckart]

I tried the jar:https://repo.maven.apache.org/maven2/org/eclipse/jetty/jetty-p2/10.0.9/jetty-p2-10.0.9-p2site.zip!/ URL once with a fresh Eclipse 2022-03, once after updating to the latest release version from the m2e release update side and once with the snapshot update site - it only worked after I had installed m2e from the snapshot site 🤷

[laeubi]

You must use mvn:org.eclipse.jetty:jetty-p2:10.0.9:zip:p2site as the repo URL.

[laeubi]

Can you please try out the current tycho snapshot build for version 2.7.3-SNAPSHOT if that fixes the problem for you?

[reckart]

Looks good 👍