How to create custom task in Gradle?

Sometimes you need to declare custom tasks in your project.

For instance, you need to copy all *.log files from files directory to the _logs_ folder:

task copyLogs(type: Copy){
    from 'logs'     // from which directory to copy
    include '*.log' // what patterns to include
    into 'archive'  // where to copy these files
}

See: Copy task type
See: Groovy strings guide

How to declare tasks chain?

What if you need to zip them afterwards? To follow the declarative style of Gradle you would better create chain of tasks rather that creating one but complex. Logically the steps are:

  • Zip all log files
  • Move it to the archive directory

So let’s define corresponding zip task:

task zipLogs(type: Zip) {

    // tell that we should copy the logs at first
    dependsOn 'copyLogs'

    // setting archive name using GString enhancement
    archiveName "logs-${LocalDateTime.now()}.zip" 

    // from what directory collect the files
    from 'logs'

    // filter closure
    include { file -> file.name.endsWith('log') }

    // where to put the result archive
    destinationDir file('archive')
}

Read more about GString: GString documentation
Read more about Groovy closure: Groovy closure

In this way can call these tasks separately but tasks are logically separated and in the same time they are chained.

In this way, you can create new task, e.g. publishLogs and say that it dependsOn zipping the files and just operate the state after zipLogs task.

For example:

task publishLogs(dependsOn: 'zipLogs') {
    doLast {
        // publish the logs or send them via e-mail
    }
}