Update Liquibase's changelog automatically while building

Question

I'm currently working on a Spring project which uses Hibernate and Liquibase. What I am trying to achieve is to update Liquibase's changelog automatically every time I build the project. It's supposed to generate a diff based on my current productive database and my updated Hibernate Entities.

But the problem I have is that every time I clean and rebuild my project I get the following error:

liquibase-plugin: Running the 'main' activity...
INFO 6/22/15 11:12 AM: liquibase-hibernate: Reading hibernate configuration hibernate:spring:com.example.name.domain?dialect=org.hibernate.dialect.MySQL5Dialect
INFO 6/22/15 11:12 AM: liquibase-hibernate: Found package com.example.app.domain
INFO 6/22/15 11:12 AM: liquibase-hibernate: Found dialect org.hibernate.dialect.MySQL5Dialect
Unexpected error running Liquibase: Unable to resolve persistence unit root URL

SEVERE 6/22/15 11:12 AM: liquibase: Unable to resolve persistence unit root URL
liquibase.exception.DatabaseException: javax.persistence.PersistenceException: Unable to resolve persistence unit root URL
        at liquibase.integration.commandline.CommandLineUtils.createDatabaseObject(CommandLineUtils.java:69)
        at liquibase.integration.commandline.Main.createReferenceDatabaseFromCommandParams(Main.java:1169)
        at liquibase.integration.commandline.Main.doMigration(Main.java:936)
        at liquibase.integration.commandline.Main.run(Main.java:175)
        at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
        at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
        at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
        at java.lang.reflect.Method.invoke(Method.java:497)
        at org.codehaus.groovy.reflection.CachedMethod.invoke(CachedMethod.java:90)
        at groovy.lang.MetaMethod.doMethodInvoke(MetaMethod.java:324)
        at org.codehaus.groovy.runtime.callsite.StaticMetaMethodSite.invoke(StaticMetaMethodSite.java:43)
        at org.codehaus.groovy.runtime.callsite.StaticMetaMethodSite.call(StaticMetaMethodSite.java:88)
        at org.codehaus.groovy.runtime.callsite.CallSiteArray.defaultCall(CallSiteArray.java:45)
        at org.codehaus.groovy.runtime.callsite.AbstractCallSite.call(AbstractCallSite.java:108)
        at org.codehaus.groovy.runtime.callsite.AbstractCallSite.call(AbstractCallSite.java:116)
        at org.liquibase.gradle.LiquibaseTask.runLiquibase(LiquibaseTask.groovy:97)
        at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
        at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
        at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
        at java.lang.reflect.Method.invoke(Method.java:497)
        at org.codehaus.groovy.reflection.CachedMethod.invoke(CachedMethod.java:90)
        at groovy.lang.MetaMethod.doMethodInvoke(MetaMethod.java:324)
        at org.codehaus.groovy.runtime.metaclass.ClosureMetaClass.invokeMethod(ClosureMetaClass.java:382)
        at groovy.lang.MetaClassImpl.invokeMethod(MetaClassImpl.java:1015)
        at org.codehaus.groovy.runtime.callsite.PogoMetaClassSite.callCurrent(PogoMetaClassSite.java:66)
        at org.codehaus.groovy.runtime.callsite.CallSiteArray.defaultCallCurrent(CallSiteArray.java:49)
        at org.codehaus.groovy.runtime.callsite.AbstractCallSite.callCurrent(AbstractCallSite.java:133)
        at org.codehaus.groovy.runtime.callsite.AbstractCallSite.callCurrent(AbstractCallSite.java:141)
        at org.liquibase.gradle.LiquibaseTask$_liquibaseAction_closure1.doCall(LiquibaseTask.groovy:52)
        at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
        at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
        at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
        at java.lang.reflect.Method.invoke(Method.java:497)
        at org.codehaus.groovy.reflection.CachedMethod.invoke(CachedMethod.java:90)
        at groovy.lang.MetaMethod.doMethodInvoke(MetaMethod.java:324)
        at org.codehaus.groovy.runtime.metaclass.ClosureMetaClass.invokeMethod(ClosureMetaClass.java:292)
        at groovy.lang.MetaClassImpl.invokeMethod(MetaClassImpl.java:1015)
        at groovy.lang.Closure.call(Closure.java:423)
        at groovy.lang.Closure.call(Closure.java:439)
        at org.codehaus.groovy.runtime.DefaultGroovyMethods.each(DefaultGroovyMethods.java:1379)
        at org.codehaus.groovy.runtime.DefaultGroovyMethods.each(DefaultGroovyMethods.java:1310)
        at org.codehaus.groovy.runtime.dgm$150.invoke(Unknown Source)
        at org.codehaus.groovy.runtime.callsite.PojoMetaMethodSite$PojoMetaMethodSiteNoUnwrapNoCoerce.invoke(PojoMetaMethodSite.java:271)
        at org.codehaus.groovy.runtime.callsite.PojoMetaMethodSite.call(PojoMetaMethodSite.java:53)
        at org.codehaus.groovy.runtime.callsite.CallSiteArray.defaultCall(CallSiteArray.java:45)
        at org.codehaus.groovy.runtime.callsite.AbstractCallSite.call(AbstractCallSite.java:108)
        at org.codehaus.groovy.runtime.callsite.AbstractCallSite.call(AbstractCallSite.java:116)
        at org.liquibase.gradle.LiquibaseTask.liquibaseAction(LiquibaseTask.groovy:46)
        at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
        at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
        at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
        at java.lang.reflect.Method.invoke(Method.java:497)
        at org.gradle.internal.reflect.JavaMethod.invoke(JavaMethod.java:75)
        at org.gradle.api.internal.project.taskfactory.AnnotationProcessingTaskFactory$StandardTaskAction.doExecute(AnnotationProcessingTaskFactory.java:226)
        at org.gradle.api.internal.project.taskfactory.AnnotationProcessingTaskFactory$StandardTaskAction.execute(AnnotationProcessingTaskFactory.java:219)
        at org.gradle.api.internal.project.taskfactory.AnnotationProcessingTaskFactory$StandardTaskAction.execute(AnnotationProcessingTaskFactory.java:208)
        at org.gradle.api.internal.AbstractTask$TaskActionWrapper.execute(AbstractTask.java:589)
        at org.gradle.api.internal.AbstractTask$TaskActionWrapper.execute(AbstractTask.java:572)
        at org.gradle.api.internal.tasks.execution.ExecuteActionsTaskExecuter.executeAction(ExecuteActionsTaskExecuter.java:80)
        at org.gradle.api.internal.tasks.execution.ExecuteActionsTaskExecuter.executeActions(ExecuteActionsTaskExecuter.java:61)
        at org.gradle.api.internal.tasks.execution.ExecuteActionsTaskExecuter.execute(ExecuteActionsTaskExecuter.java:46)
        at org.gradle.api.internal.tasks.execution.PostExecutionAnalysisTaskExecuter.execute(PostExecutionAnalysisTaskExecuter.java:35)
        at org.gradle.api.internal.tasks.execution.SkipUpToDateTaskExecuter.execute(SkipUpToDateTaskExecuter.java:64)
        at org.gradle.api.internal.tasks.execution.ValidatingTaskExecuter.execute(ValidatingTaskExecuter.java:58)
        at org.gradle.api.internal.tasks.execution.SkipEmptySourceFilesTaskExecuter.execute(SkipEmptySourceFilesTaskExecuter.java:42)
        at org.gradle.api.internal.tasks.execution.SkipTaskWithNoActionsExecuter.execute(SkipTaskWithNoActionsExecuter.java:52)
        at org.gradle.api.internal.tasks.execution.SkipOnlyIfTaskExecuter.execute(SkipOnlyIfTaskExecuter.java:53)
        at org.gradle.api.internal.tasks.execution.ExecuteAtMostOnceTaskExecuter.execute(ExecuteAtMostOnceTaskExecuter.java:43)
        at org.gradle.api.internal.AbstractTask.executeWithoutThrowingTaskFailure(AbstractTask.java:310)
        at org.gradle.api.internal.AbstractTask.execute(AbstractTask.java:305)
        at org.gradle.api.internal.TaskInternal$execute$0.call(Unknown Source)
        at org.codehaus.groovy.runtime.callsite.CallSiteArray.defaultCall(CallSiteArray.java:45)
        at org.codehaus.groovy.runtime.callsite.AbstractCallSite.call(AbstractCallSite.java:108)
        at org.codehaus.groovy.runtime.callsite.AbstractCallSite.call(AbstractCallSite.java:112)
        at build_au43cnsvyw2rwctsxb5mg4cmw$_run_closure4.doCall(/Users/mihajlovic/Documents/repos/Backend/dbmigration/build.gradle:52)
        at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
        at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
        at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
        at java.lang.reflect.Method.invoke(Method.java:497)
        at org.codehaus.groovy.reflection.CachedMethod.invoke(CachedMethod.java:90)
        at groovy.lang.MetaMethod.doMethodInvoke(MetaMethod.java:324)
        at org.codehaus.groovy.runtime.metaclass.ClosureMetaClass.invokeMethod(ClosureMetaClass.java:292)
        at groovy.lang.MetaClassImpl.invokeMethod(MetaClassImpl.java:1015)
        at groovy.lang.Closure.call(Closure.java:423)
        at groovy.lang.Closure.call(Closure.java:439)
        at org.gradle.api.internal.AbstractTask$ClosureTaskAction.execute(AbstractTask.java:558)
        at org.gradle.api.internal.AbstractTask$ClosureTaskAction.execute(AbstractTask.java:539)
        at org.gradle.api.internal.tasks.TaskMutator$1.execute(TaskMutator.java:77)
        at org.gradle.api.internal.tasks.TaskMutator$1.execute(TaskMutator.java:73)
        at org.gradle.api.internal.tasks.execution.ExecuteActionsTaskExecuter.executeAction(ExecuteActionsTaskExecuter.java:80)
        at org.gradle.api.internal.tasks.execution.ExecuteActionsTaskExecuter.executeActions(ExecuteActionsTaskExecuter.java:61)
        at org.gradle.api.internal.tasks.execution.ExecuteActionsTaskExecuter.execute(ExecuteActionsTaskExecuter.java:46)
        at org.gradle.api.internal.tasks.execution.PostExecutionAnalysisTaskExecuter.execute(PostExecutionAnalysisTaskExecuter.java:35)
        at org.gradle.api.internal.tasks.execution.SkipUpToDateTaskExecuter.execute(SkipUpToDateTaskExecuter.java:64)
        at org.gradle.api.internal.tasks.execution.ValidatingTaskExecuter.execute(ValidatingTaskExecuter.java:58)
        at org.gradle.api.internal.tasks.execution.SkipEmptySourceFilesTaskExecuter.execute(SkipEmptySourceFilesTaskExecuter.java:42)
        at org.gradle.api.internal.tasks.execution.SkipTaskWithNoActionsExecuter.execute(SkipTaskWithNoActionsExecuter.java:52)
        at org.gradle.api.internal.tasks.execution.SkipOnlyIfTaskExecuter.execute(SkipOnlyIfTaskExecuter.java:53)
        at org.gradle.api.internal.tasks.execution.ExecuteAtMostOnceTaskExecuter.execute(ExecuteAtMostOnceTaskExecuter.java:43)
        at org.gradle.api.internal.AbstractTask.executeWithoutThrowingTaskFailure(AbstractTask.java:310)
        at org.gradle.execution.taskgraph.AbstractTaskPlanExecutor$TaskExecutorWorker.executeTask(AbstractTaskPlanExecutor.java:79)
        at org.gradle.execution.taskgraph.AbstractTaskPlanExecutor$TaskExecutorWorker.processTask(AbstractTaskPlanExecutor.java:63)
        at org.gradle.execution.taskgraph.AbstractTaskPlanExecutor$TaskExecutorWorker.run(AbstractTaskPlanExecutor.java:51)
        at org.gradle.execution.taskgraph.DefaultTaskPlanExecutor.process(DefaultTaskPlanExecutor.java:23)
        at org.gradle.execution.taskgraph.DefaultTaskGraphExecuter.execute(DefaultTaskGraphExecuter.java:88)
        at org.gradle.execution.SelectedTaskExecutionAction.execute(SelectedTaskExecutionAction.java:37)
        at org.gradle.execution.DefaultBuildExecuter.execute(DefaultBuildExecuter.java:62)
        at org.gradle.execution.DefaultBuildExecuter.access$200(DefaultBuildExecuter.java:23)
        at org.gradle.execution.DefaultBuildExecuter$2.proceed(DefaultBuildExecuter.java:68)
        at org.gradle.execution.DryRunBuildExecutionAction.execute(DryRunBuildExecutionAction.java:32)
        at org.gradle.execution.DefaultBuildExecuter.execute(DefaultBuildExecuter.java:62)
        at org.gradle.execution.DefaultBuildExecuter.execute(DefaultBuildExecuter.java:55)
        at org.gradle.initialization.DefaultGradleLauncher.doBuildStages(DefaultGradleLauncher.java:149)
        at org.gradle.initialization.DefaultGradleLauncher.doBuild(DefaultGradleLauncher.java:106)
        at org.gradle.initialization.DefaultGradleLauncher.run(DefaultGradleLauncher.java:86)
        at org.gradle.launcher.exec.InProcessBuildActionExecuter$DefaultBuildController.run(InProcessBuildActionExecuter.java:90)
        at org.gradle.tooling.internal.provider.ExecuteBuildActionRunner.run(ExecuteBuildActionRunner.java:28)
        at org.gradle.launcher.exec.ChainingBuildActionRunner.run(ChainingBuildActionRunner.java:35)
        at org.gradle.launcher.exec.InProcessBuildActionExecuter.execute(InProcessBuildActionExecuter.java:41)
        at org.gradle.launcher.exec.InProcessBuildActionExecuter.execute(InProcessBuildActionExecuter.java:28)
        at org.gradle.launcher.exec.DaemonUsageSuggestingBuildActionExecuter.execute(DaemonUsageSuggestingBuildActionExecuter.java:50)
        at org.gradle.launcher.exec.DaemonUsageSuggestingBuildActionExecuter.execute(DaemonUsageSuggestingBuildActionExecuter.java:27)
        at org.gradle.launcher.cli.RunBuildAction.run(RunBuildAction.java:40)
        at org.gradle.internal.Actions$RunnableActionAdapter.execute(Actions.java:169)
        at org.gradle.launcher.cli.CommandLineActionFactory$ParseAndBuildAction.execute(CommandLineActionFactory.java:237)
        at org.gradle.launcher.cli.CommandLineActionFactory$ParseAndBuildAction.execute(CommandLineActionFactory.java:210)
        at org.gradle.launcher.cli.JavaRuntimeValidationAction.execute(JavaRuntimeValidationAction.java:35)
        at org.gradle.launcher.cli.JavaRuntimeValidationAction.execute(JavaRuntimeValidationAction.java:24)
        at org.gradle.launcher.cli.CommandLineActionFactory$WithLogging.execute(CommandLineActionFactory.java:206)
        at org.gradle.launcher.cli.CommandLineActionFactory$WithLogging.execute(CommandLineActionFactory.java:169)
        at org.gradle.launcher.cli.ExceptionReportingAction.execute(ExceptionReportingAction.java:33)
        at org.gradle.launcher.cli.ExceptionReportingAction.execute(ExceptionReportingAction.java:22)
        at org.gradle.launcher.Main.doAction(Main.java:33)
        at org.gradle.launcher.bootstrap.EntryPoint.run(EntryPoint.java:45)
        at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
        at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
        at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
        at java.lang.reflect.Method.invoke(Method.java:497)
        at org.gradle.launcher.bootstrap.ProcessBootstrap.runNoExit(ProcessBootstrap.java:54)
        at org.gradle.launcher.bootstrap.ProcessBootstrap.run(ProcessBootstrap.java:35)
        at org.gradle.launcher.GradleMain.main(GradleMain.java:23)
Caused by: javax.persistence.PersistenceException: Unable to resolve persistence unit root URL
        at org.springframework.orm.jpa.persistenceunit.DefaultPersistenceUnitManager.determineDefaultPersistenceUnitRootUrl(DefaultPersistenceUnitManager.java:580)
        at org.springframework.orm.jpa.persistenceunit.DefaultPersistenceUnitManager.preparePersistenceUnitInfos(DefaultPersistenceUnitManager.java:436)
        at liquibase.ext.hibernate.database.HibernateSpringDatabase.buildConfigurationFromScanning(HibernateSpringDatabase.java:227)
        at liquibase.ext.hibernate.database.HibernateSpringDatabase.buildConfiguration(HibernateSpringDatabase.java:55)
        at liquibase.ext.hibernate.database.HibernateDatabase.setConnection(HibernateDatabase.java:45)
        at liquibase.database.DatabaseFactory.findCorrectDatabaseImplementation(DatabaseFactory.java:123)
        at liquibase.database.DatabaseFactory.openDatabase(DatabaseFactory.java:143)
        at liquibase.integration.commandline.CommandLineUtils.createDatabaseObject(CommandLineUtils.java:50)
        ... 140 more
Caused by: java.io.FileNotFoundException: class path resource [] cannot be resolved to URL because it does not exist
        at org.springframework.core.io.ClassPathResource.getURL(ClassPathResource.java:187)
        at org.springframework.orm.jpa.persistenceunit.DefaultPersistenceUnitManager.determineDefaultPersistenceUnitRootUrl(DefaultPersistenceUnitManager.java:577)
        ... 147 more

---

As far as I understand it the problem is that Liquibase requires all the entity classes to be loaded into gradle's classpath, but since the Java classes are just being compiled or have not been compiled that is not the case yet, hence the error message.

I can fix this error by building the project in two steps:

1. First I execute the task compileJava to build the entity classes.
2. Once that is done I can perform a normal build - now without any problems.

However building the project in two steps is quite tedious. Is there a way I can work around this issue to build it in just one step?

My build.gradle currently looks like this:

buildscript {
    ext {
        springBootVersion = '1.2.3.RELEASE'
    }
    repositories {
        mavenCentral()
        files 'build/classes/main'
    }
    dependencies {
        classpath("org.springframework.boot:spring-boot-gradle-plugin:${springBootVersion}")
        classpath("io.spring.gradle:dependency-management-plugin:0.5.0.RELEASE")
        classpath("org.liquibase:liquibase-gradle-plugin:1.1.0")
        classpath("mysql:mysql-connector-java:5.1.35")
        classpath('org.hibernate.javax.persistence:hibernate-jpa-2.1-api:1.0.0.Final')
        classpath('org.liquibase.ext:liquibase-hibernate4:3.5')
        classpath('org.springframework.data:spring-data-jpa:1.8.0.RELEASE')
        classpath files('build/classes/main/')

    }
}

apply plugin: 'org.liquibase.gradle'
apply plugin: 'java'
apply plugin: 'eclipse-wtp'
apply plugin: 'idea'
apply plugin: 'spring-boot'
apply plugin: 'io.spring.dependency-management'
apply plugin: 'war'


war {
    baseName = 'example'
    version = '0.0.1-SNAPSHOT'
}
sourceCompatibility = 1.8
targetCompatibility = 1.8

repositories {
    mavenCentral()

    flatDir {
        dirs 'libs'
    }
}

configurations {
    providedRuntime
}

dependencies {
    compile("org.springframework.boot:spring-boot-starter-data-jpa")
    compile("org.springframework.boot:spring-boot-starter-web")
    compile("org.apache.commons:commons-lang3:3.0")
    compile("mysql:mysql-connector-java:5.1.35")
    compile('org.liquibase:liquibase-core:3.3.5')

    providedRuntime("org.springframework.boot:spring-boot-starter-tomcat")
    testCompile("org.springframework.boot:spring-boot-starter-test")
}

liquibase {
    activities {
        main {
            changeLogFile 'src/main/resources/db/changelog/db.changelog-master.xml'
            url 'jdbc:mysql://localhost:3306/Example'
            username 'root'
            password ''
            referenceDriver 'liquibase.ext.hibernate.database.connection.HibernateDriver'
            referenceUrl 'hibernate:spring:com.example.app.domain?dialect=org.hibernate.dialect.MySQL5Dialect'
        }
    }
    runList = 'main'
}



eclipse {
    classpath {
        containers.remove('org.eclipse.jdt.launching.JRE_CONTAINER')
        containers 'org.eclipse.jdt.launching.JRE_CONTAINER/org.eclipse.jdt.internal.debug.ui.launcher.StandardVMType/JavaSE-1.7'
    }
}

task wrapper(type: Wrapper) {
    gradleVersion = '2.4'
}

Answer 1

I finally figured it out! You can use the Exec type to execute commands in the command line which subsequently starts a new process. You can find more information in the documentation.

This is the solution I ended up with:

task updateChangeLog(type: Exec) {
    commandLine 'gradle', 'diffChangeLog'
}
updateChangeLog.dependsOn compileJava

This starts a new separate gradle process with my diffChangeLog task.