Maven does not delete extra artifacts from repository server

Question

I deployed my java projects artifacts on a repository server using mvn deploy command. When i deployed the artifacts (release version) this time i also deployed javadocs and source using following in code snippet.

<build>
        <plugins>
            <plugin>
                <groupId>org.apache.maven.plugins</groupId>
                <artifactId>maven-source-plugin</artifactId>
                <executions>
                    <execution>
                        <id>attach-sources</id>
                        <goals>
                            <goal>jar</goal>
                        </goals>
                    </execution>
                </executions>
            </plugin>
            <plugin>
                <groupId>org.apache.maven.plugins</groupId>
                <artifactId>maven-javadoc-plugin</artifactId>
                <executions>
                    <execution>
                        <id>attach-javadocs</id>
                        <goals>
                            <goal>jar</goal>
                        </goals>
                    </execution>
                </executions>
            </plugin>
        </plugins>

    </build>

Now I deployed the same project(Same release version) by commenting above snippet , maven dint delete extra artifacts (source and javadocs) .Is this expected?

Answer 1

This is normal behavior.

You should not re-deploy released versions. Here are the reasons:

• Other developers and continuous integration (CI) servers might have already downloaded this version of the artifact and have it in their local build tools' caches (Maven, Ivy, SBT, Gradle, etc). These build tools will never EVER check again in the remote, if the released versions have been downloaded into the local cache. Hence, they will never know that you have deployed a new version of the same artifact.
• There might be builds and assemblies that already depend on your artifact and include it. This could be a packaged inside a WAR/JAR, or even shaded inside a jar.
• If you re-deploy the same version, you might break debugging data handed to you by your users. If some developer doesn't have the jar in their cache and rebuilds the tag on which this was based and all the dependencies get fetched and cached locally, things like stacktraces and thread dumps will be off and the developer(s) will waste precious time figuring out what's wrong with a) their environment and b) the debugging data.
• If you re-deploy released versions, developers will look bad at you. This is a well-known poor practice and should always be avoided, unless you have just released 5 minutes ago and are perfectly sure that nobody else is using this code yet.

When you've realized you have an issue with your code and you've already released, the advised practice (unless you're using a staging repository), is to just deploy a new release with an incremented number. The more often you deploy new versions (with reason, of course), the more confident the users of your library/product will be that the development is active and things are (hopefully) fixed. Re-deploying the same version silently will most-certainly cause chaos and sleepless nights.

Also, Maven doesn't:

• Delete artifacts
• Delete entries from your maven-metadata.xml files

This is up to you. You need to rebuild the metadata using your artifact repository manager, if it's already deployed, (unless this is a snapshot).