How to read a properties files and use the values in project Gradle script?

I am working on a Gradle script where I need to read the local.properties file and use the values in the properties file in build.gradle. I am doing it in the below manner. I ran the below script and it is now throwing an error, but it is also not doing anything like creating, deleting, and copying the file. I tried to print the value of the variable and it is showing the correct value.

Can someone let me know if this is the correct way to do this? I think the other way is to define everything in the gradle.properties and use it in the build.gradle. Can someone let me know how could I access the properties in build.gradle from build.properties?

build.gradle file:

apply plugin: 'java'

// Set the group for publishing
group = 'com.true.test'

/**
 * Initializing GAVC settings
 */
def buildProperties = new Properties()
file("version.properties").withInputStream {
        stream -> buildProperties.load(stream)
}
// If jenkins build, add the jenkins build version to the version. Else add snapshot version to the version.
def env = System.getenv()
if (env["BUILD_NUMBER"]) buildProperties.test+= ".${env["BUILD_NUMBER"]}"
version = buildProperties.test
println "${version}"

// Name is set in the settings.gradle file
group = "com.true.test"
version = buildProperties.test
println "Building ${project.group}:${project.name}:${project.version}"

Properties properties = new Properties()
properties.load(project.file('build.properties').newDataInputStream())
def folderDir = properties.getProperty('build.dir')
def configDir = properties.getProperty('config.dir')
def baseDir  = properties.getProperty('base.dir')
def logDir  = properties.getProperty('log.dir')
def deployDir  = properties.getProperty('deploy.dir')
def testsDir  = properties.getProperty('tests.dir')
def packageDir  = properties.getProperty('package.dir')
def wrapperDir  = properties.getProperty('wrapper.dir')


sourceCompatibility = 1.7
compileJava.options.encoding = 'UTF-8'

repositories {
     maven { url "http://arti.oven.c:9000/release" }
  }

task swipe(type: Delete) {
         println "Delete $projectDir/${folderDir}"
         delete "$projectDir/$folderDir"
	     delete "$projectDir/$logDir"
         delete "$projectDir/$deployDir"
	     delete "$projectDir/$packageDir"
	     delete "$projectDir/$testsDir"
	     mkdir("$projectDir/${folderDir}")
	     mkdir("projectDir/${logDir}")
	     mkdir("projectDir/${deployDir}")
	     mkdir("projectDir/${packageDir}")
	     mkdir("projectDir/${testsDir}")
}
task prepConfigs(type: Copy, overwrite:true, dependsOn: swipe) {
    println "The name of ${projectDir}/${folderDir} and ${projectDir}/${configDir}"
    from('${projectDir}/${folderDir}')
    into('${projectDir}/$configDir}')
    include('*.xml')
}

build.properties file:

# -----------------------------------------------------------------
# General Settings
# -----------------------------------------------------------------
application.name  = Admin
project.name = Hello Cool

# -----------------------------------------------------------------
# ant build directories
# -----------------------------------------------------------------
sandbox.dir = ${projectDir}/../..
reno.root.dir=${sandbox.dir}/Reno
ant.dir = ${projectDir}/ant
build.dir = ${ant.dir}/build
log.dir  = ${ant.dir}/logs
config.dir = ${ant.dir}/configs
deploy.dir  = ${ant.dir}/deploy
static.dir =  ${ant.dir}/static
package.dir = ${ant.dir}/package
tests.dir = ${ant.dir}/tests
tests.logs.dir = ${tests.dir}/logs
external.dir = ${sandbox.dir}/FlexCommon/External
external.lib.dir = ${external.dir}/libs

If using the default gradle.properties file, you can access the properties directly from within your build.gradle file:

gradle.properties:

applicationName=Admin
projectName=Hello Cool

build.gradle:

task printProps {
    doFirst {
        println applicationName
        println projectName
    }
}

If you need to access a custom file, or access properties which include . in them (as it appears you need to do), you can do the following in your build.gradle file:

def props = new Properties()
file("build.properties").withInputStream { props.load(it) }

task printProps {
    doFirst {
        println props.getProperty("application.name")
        println props.getProperty("project.name")
    }
}

Take a look at this section of the Gradle documentation for more information.

Edit

If you'd like to dynamically set up some of these properties (as mentioned in a comment below), you can create a properties.gradle file (the name isn't important) and require it in your build.gradle script.

properties.gradle:

ext {
    subPath = "some/sub/directory"
    fullPath = "$projectDir/$subPath"
}

build.gradle

apply from: 'properties.gradle'

// prints the full expanded path
println fullPath

We can use a separate file (config.groovy in my case) to abstract out all the configuration.

In this example, we're using three environments viz.,

1. dev
2. test
3. prod

which has properties serverName, serverPort and resources. Here we're expecting that the third property resources may be same in multiple environments and so we've abstracted out that logic and overridden in the specific environment wherever necessary:

config.groovy

resources {
    serverName = 'localhost'
    serverPort = '8090'
}
 
environments {
    dev {
        serverName = 'http://localhost'   
		serverPort = '8080'
    }
     
    test {
        serverName = 'http://www.testserver.com'
		serverPort = '5211'
        resources {
            serverName = 'resources.testserver.com'
        }
    }
     
    prod {
        serverName = 'http://www.productionserver.com'
		serverPort = '80'
        resources {
			serverName = 'resources.productionserver.com'
			serverPort = '80'
        }
    }
}

Once the properties file is ready, we can use the following in build.gradle to load these settings:

build.gradle

loadProperties()
  
def loadProperties() {
    def environment = hasProperty('env') ? env : 'dev'
    println "Current Environment: " + environment
     
    def configFile = file('config.groovy')
    def config = new ConfigSlurper(environment).parse(configFile.toURL())
    project.ext.config = config
}

task printProperties {
    println "serverName:  $config.serverName"
    println "serverPort:  $config.serverPort"
    println "resources.serverName:  $config.resources.serverName"
    println "resources.serverPort:  $config.resources.serverPort"
}

---

Let's run these with different set of inputs:

1. gradle -q printProperties

   Current Environment: dev
   serverName:  http://localhost
   serverPort:  8080
   resources.serverName:  localhost
   resources.serverPort:  8090
   

2. gradle -q -Penv=dev printProperties

   Current Environment: dev
   serverName:  http://localhost
   serverPort:  8080
   resources.serverName:  localhost
   resources.serverPort:  8090
   

3. gradle -q -Penv=test printProperties

   Current Environment: test
   serverName:  http://www.testserver.com
   serverPort:  5211
   resources.serverName:  resources.testserver.com
   resources.serverPort:  8090
   

4. gradle -q -Penv=prod printProperties

   Current Environment: prod
   serverName:  http://www.productionserver.com
   serverPort:  80
   resources.serverName:  resources.productionserver.com
   resources.serverPort:  80
   

Another way... in build.gradle:

Add :

classpath 'org.flywaydb:flyway-gradle-plugin:3.1'

And this :

def props = new Properties()
file("src/main/resources/application.properties").withInputStream { props.load(it) }
apply plugin: 'flyway'
flyway {
    url = props.getProperty("spring.datasource.url")
    user = props.getProperty("spring.datasource.username")
    password = props.getProperty("spring.datasource.password")
    schemas = ['db_example']
}

This is for Kotlin DSL (build.gradle.kts):

import java.util.*
// ...

val properties = Properties().apply {
    load(rootProject.file("my-local.properties").reader())
}
val prop = properties["myPropName"]

In Android projects (when applying the android plugin) you can also do this:

import com.android.build.gradle.internal.cxx.configure.gradleLocalProperties
// ...

val properties = gradleLocalProperties(rootDir)
val prop = properties["propName"]