The Liquibase Plugin as a Buildfile

liquibase.gradle

import org.gradle.api.NamedDomainObjectContainer
import org.gradle.api.Plugin
import org.gradle.api.Project
import org.gradle.api.DefaultTask
import org.gradle.api.tasks.TaskAction
import liquibase.integration.commandline.Main

apply plugin: LiquibasePlugin

buildscript {
  repositories {
    mavenCentral()
  }
  dependencies {
    classpath 'com.h2database:h2:1.3.159'
    classpath 'org.liquibase:liquibase-core:2.0.3'
  }
}

class ChangeLog
{
  def name
  def file
  def description

  ChangeLog(String name) {
    this.name = name
  }
}

class Database
{
  def name
  def url
  def username
  def password

  Database(String name) {
    this.name = name
  }
}

class LiquibaseTask extends DefaultTask {
  Database database
  String command
  def changeLogs

  @TaskAction
  def liquibaseAction() {
    if(database == null) {
      database = project.liquibase.defaultDatabase
    }

    if(changeLogs == null) {
      changeLogs = project.liquibase.changelogs
    }
    
    changeLogs.each { changeLog ->
      def args = [ 
        "--url=${database.url}", 
        "--password=${database.password}", 
        "--username=${database.username}",
        "--changeLogFile=${changeLog.file.absolutePath}",
        command
      ]

      Main.main(args as String[])
    }
  }
}

class LiquibaseExtension {
  final NamedDomainObjectContainer<Database> databases
  final NamedDomainObjectContainer<ChangeLog> changelogs
  Database defaultDatabase
  String context

  LiquibaseExtension(databases, changelogs) {
    this.databases = databases
    this.changelogs = changelogs
  }

  def databases(Closure closure) {
    databases.configure(closure)
  }

  def changelogs(Closure closure) {
    println closure
    changelogs.configure(closure)
    println changelogs
  }
}

class LiquibasePlugin implements Plugin<Project> {
  void apply(Project project) {
    // Create and install custom tasks
    project.task('generateChangeLog', type: LiquibaseTask) {
      group = 'Liquibase'
      command = 'generateChangeLog'
    }
    project.task('changeLogSync', type: LiquibaseTask) {
      group = 'Liquibase'
      command = 'changeLogSync'
    }
    project.task('update', type: LiquibaseTask) {
      group = 'Liquibase'
      command = 'update'
    }
    
    // Create and install the extension object
    project.extensions.create("liquibase",
                              LiquibaseExtension,
                              project.container(Database),
                              project.container(ChangeLog))
  }
}

liquibase {
  changelogs { 
    main {
      file = file('changelog.xml')
    }
  }

  databases { 
    sandbox {
      url = 'jdbc:h2:db/liquibase_workshop;FILE_LOCK=NO'
      username = 'sa'
      password = ''
    }
  }

  defaultDatabase = databases.sandbox
}