build-helper-maven-plugin: unable to use replaced value with other plugins - regex

Question

I have a Google App Engine Standard Maven project, which I created with the appengine-standard-archetype archetype.
I want to use the ${project.version} variable as deploy version, but the value is not allowed for certain characters:
May only contain lowercase letters, digits, and hyphens. Must begin
and end with a letter or digit. Must not exceed 63 characters.
The value 0.0.1-SNAPSHOT need to be modified. I then used the build-helper-maven-plugin to obtain the replacement
<plugin>
<groupId>org.codehaus.mojo</groupId>
<artifactId>build-helper-maven-plugin</artifactId>
<version>3.0.0</version>
<executions>
<execution>
<id>version-urlsafe</id>
<goals>
<goal>regex-property</goal>
</goals>
<configuration>
<name>project.version.urlsafe</name>
<value>${project.version}</value>
<regex>\.</regex>
<replacement>-</replacement>
<toLowerCase>true</toLowerCase>
<failIfNoMatch>false</failIfNoMatch>
</configuration>
</execution>
</executions>
</plugin>
And the maven-antrun-plugin to show the value
<plugin>
<artifactId>maven-antrun-plugin</artifactId>
<version>1.8</version>
<executions>
<execution>
<id>regex-replace-echo</id>
<phase>package</phase>
<goals>
<goal>run</goal>
</goals>
<configuration>
<tasks>
<echo>******** Displaying value of property ********</echo>
<echo>${project.version.urlsafe}</echo>
</tasks>
</configuration>
</execution>
</executions>
</plugin>
At the end I used the new property as version for deploy
<app.deploy.version>${project.version.urlsafe}-urlsafe</app.deploy.version>
Note that I add the -urlsafe at the end of the value only to understand why the value is not considered
Running the deploy with mvn appengine:deploy I'm getting this output
...
[INFO] Executing tasks
main:
[echo] ******** Displaying value of property ********
[echo] 0-0-1-snapshot
...
gcloud.cmd app deploy --version ${project.version.urlsafe}-urlsafe
[INFO] GCLOUD: ERROR: (gcloud.app.deploy) argument --version/-v: Bad value [${project.version.urlsafe}-urlsafe]
Even if the ant-run plugin properly echoed the new version, when the deploy command is built, the variable itself is missing.
I then tried forcing the regex-property goal before the deploy, like follows
mvn build-helper:regex-property appengine:deploy
but I'm getting a missing configuration error in this case:
[ERROR] Failed to execute goal org.codehaus.mojo:build-helper-maven-plugin:3.0.0:regex-property (default-cli) on project maventest: The parameters 'regex', 'name', 'value' for goal org.codehaus.mojo:build-helper-maven-plugin:3.0.0:regex-property are missing or invalid -> [Help 1]
A little digression:
I decided to manually run the build-helper:regex-property as additional goal due to a previous experience with a similar a case: a plugin that inject a new variable, which is properly echoed but when it comes to use the value, is missing. Here is the reference: Unable to obtaing git.branch property
Cooperating with the plugin author we found that adding the plugin goal before the appengine one can solve the issue mvn git-commit-id:revision appengine:deploy. At the end the root cause of this problem was a Maven bug: https://issues.apache.org/jira/browse/MNG-6260
So even the workaround of directly calling the plugin is not suitable in this case due to a plugin configuration error.
How can issue can be solved? How can I obtain the ${project.version.urlsafe} variable properly created when executing the appengine deploy?

Answer 1

I had the same problem using the appengine-maven-plugin. And you're right, you need to first call the goal build-helper:regex-property before deploying on app engine.
But to make this work, you have to move the configuration part outside the executions tag.
Here is the complete configuration I am currently using:
<plugin>
<groupId>org.codehaus.mojo</groupId>
<artifactId>build-helper-maven-plugin</artifactId>
<version>3.0.0</version>
<configuration>
<name>project.version.urlsafe</name>
<value>${project.version}</value>
<regex>\.</regex>
<replacement>-</replacement>
<toLowerCase>true</toLowerCase>
<failIfNoMatch>false</failIfNoMatch>
<fileSet/>
<source/>
</configuration>
</plugin>
Then when calling mvn build-helper:regex-property appengine:deploy, everything should work as expected.