[MNG-3508] Allow 'once' configuration item on plugin execution

[jira-importer]

Ittay Dror opened MNG-3508 and commented

Scenario:

• parent pom defines modules A, B
• it also defines a plugin with some execution
• when it runs, the plugin runs 3 times (for parent, A, B)

Now, I can set 'inherited' to false, but then if I just run 'A', the plugin won't execute.

What I'd like is to be able to configure the execution to run 'once' in the lifecycle. This is useful mainly for plugins that do some kind of setup, initialization or validation, which in many cases need to be done once per execution.

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2 votes, 7 watchers

[jira-importer]

Brian E. Fox (imported) commented

http://docs.codehaus.org/display/MAVEN/Atypical+Plugin+Use+Cases

[jira-importer]

Jason van Zyl commented

Please refer to https://cwiki.apache.org/confluence/display/MAVEN/The+Great+JIRA+Cleanup+of+2014

[jira-importer]

Jason van Zyl commented

Please refer to https://cwiki.apache.org/confluence/display/MAVEN/The+Great+JIRA+Cleanup+of+2014 if you're wondering why this issue was closed out.

[jira-importer]

Paul Benedict commented

I am reopening this ticket. This request seems perfectly reasonable. As evidenced by the many "how to" questions on the web, it is a frequently encountered problem without a perfect solution. Prime example is from Brian's Sonatype blog post, and there are others I could cite (lots on Stack Overflow), but please see for yourself by searching "maven plugin run once".

Here is my use case. This is a real example from a custom plugin:

1. Plugin manages an external resource.
2. Plugin gets management configuration from the session (somewhere in the project hierarchy) in the form of properties.
3. Plugin must validly operate when bound to a phase.
4. Plugin must validly operate when directly executed from CLI.
5. Plugin must validly operate from any execution root in a multi-module build.
6. Plugin must execute only once per build (especially important in conjunction with Avoid mixing two flavours of Guice on the classpath. #5).

At this moment only custom solutions exist – code yourself a workaround/hack. An official solution would be welcomed.

PS: It doesn't seem @Mojo(executionStrategy = "once-per-session") accomplishes this. That's surprising to me because, at least on its face, the attribute name seems to suggest it? Since my plugin runs in every project of a multi-module build, I suppose that means each project gets a new session?

[jira-importer]

Delany commented

Given the other changes in the reactor for Maven 4, this might be a good time to implement.