A Gradle plugin to control ordering of task execution between projects.

What problem does this plugin solve?

Normally in Gradle you control task execution order by setting a mustRunAfter relationship.

You can do this between tasks in the same project:

taskA.mustRunAfter taskB

Or between tasks in different projects:

findProject('projectA').tasks['myTask'].mustRunAfter findProject('projectB').tasks['myTask']

If you need to control task execution order between projects then the above code is OK for simple use cases.

As the number of projects increases though, the amount of repeated code and maintenance required goes up. Hence, the Project Order Plugin was created.

Usage

Apply the Project Order Plugin to your build.gradle:

plugins {
    id 'com.tomgregory.project-order' version '1.0.0'
}

The plugin should only be applied to a single parent project. It will inspect all subprojects of the project it is applied to.

For the plugin to do anything, you need to apply the following configuration in build.gradle:

projectOrder {
    taskNames = ['taskA', 'taskB']
}

• taskNames is a list of tasks in the subprojects, for which a mustRunAfter relationship should be applied

Ordering

The Project Order Plugin uses the following rules to determine the order in which subpproject tasks should be linked with a mustRunAfter relationship:

1. A subproject with a numeric prefix comes before one with a letter prefix i.e. 66-project before abc-project
2. Subprojects with a numeric prefix are sorted numerically i.e. 9-project before 66-project
3. Subprojects with a letter prefix are sorted alphabetically i.e. cat-project before dog-project

For more details of ordering and some examples, see ProjectComparatorTest.

An example

Imagine you have a project with multiple subprojects that each deploy infrastructure resources into the cloud:

/my-project
/my-project/networking-resources
/my-project/security-resources
/my-project/compute-resources

• each subproject of my-project has a deploy task
• the deploy tasks must get executed in the correct order, otherwise they will fail. The required order is :networking-resources:deploy then :security-resources:deploy then compute-resources:deploy

The Project Order Plugin will set a mustRunAfter relationship between the deploy task of each subproject. This will be based on the ordering as defined above.

For the plugin to work properly the projects should be renamed like this:

/my-project
/my-project/1-networking-resources
/my-project/2-security-resources
/my-project/3-compute-resources

Now this code just needs to be applied to build.gradle:

id 'com.tomgregory.project-order' version '1.0.0'

projectOrder {
    taskNames = ['deploy']
}

This same example is executed in StandaloneExampleTest and also this example repository.