Gradle multi project - execute root task only once

Question

I am working with the following project structure Project

---Subproject1

---Subproject2

---Subproject3

|build.gradle

|settings.gradle

Subproject2 depends on Subproject 1

Subproject3 depends on Subproject 2

For all subprojects I need to have task "build", which will be custom for each project. But some initialization task (same for all subprojects) must be executed before "build". Thing is - this initialization task must be executed once and only once during build, no mater what I'm building - root project or any of subprojects. For example, if I do build of Subproejct3, sequence must be following: init build Subproject1 build Subproject2 build Subproject3

I tried to define "doFirst" for "build" at root project build.gradle and put "init" code into it. But in this case "init" code executed before each "build". I tried to define dependency on root for each "build" but faced same problem as previously.

Answer 1

This is quite simple with Gradle. Define your init task (probably in root project) and customize build tasks in your subprojects to depend on this init like build.dependsOn ':init' More details at http://www.gradle.org/docs/current/userguide/tutorial_using_tasks.html

BTW: every tasks can be executed only once when a build is started so it seems that you have added your task action using doFirst() multiple times or added it to multiple tasks that were executed.