git commit gradle configuration cache

build.gradle.kts

androidComponents {
	onVariants(selector().all()) { variant ->
		val variantName = variant.name.replaceFirstChar { it.uppercase() }

        val generateConstantsTaskName = "generateBuildConstants$variantName"
        val generateConstantsTaskDescription = "Generates BuildConstants.kt with commit count and SHA for $variantName"
        val buildConstantTasks = tasks.register<GenerateBuildConstantsTask>(generateConstantsTaskName) {
            group = "build"
            description = generateConstantsTaskDescription
            outputDir.set(layout.buildDirectory.dir("generated/source/buildConstants/kotlin"))
            outputs.upToDateWhen { false }
            outputs.cacheIf { false }
        }
        variant.sources.kotlin?.addGeneratedSourceDirectory(buildConstantTasks) { tasks ->
            tasks.outputDir
        }
	}
}

tasks.kt

import org.gradle.api.DefaultTask
import org.gradle.api.file.DirectoryProperty
import org.gradle.api.file.RegularFileProperty
import org.gradle.api.provider.Property
import org.gradle.api.tasks.Input
import org.gradle.api.tasks.Internal
import org.gradle.api.tasks.OutputDirectory
import org.gradle.api.tasks.TaskAction
import org.gradle.process.ExecOperations
import java.io.ByteArrayOutputStream
import javax.inject.Inject

abstract class GenerateBuildConstantsTask @Inject constructor(
    private val execOperations: ExecOperations,
) : DefaultTask() {
    @get:OutputDirectory
    abstract val outputDir: DirectoryProperty

    @TaskAction
    fun generate() {
        val commitCountValue = getCommitCount(execOperations)
        val commitShaValue = getGitSha(execOperations)

        val packageName = "io.github.app.generated"
        val className = "BuildConstants"

        val fileContent = """
            // Generated by Gradle. Do not edit.
            package $packageName

            object $className {
                const val COMMIT_COUNT: String = "$commitCountValue"
                const val COMMIT_SHA: String = "$commitShaValue"
            }
        """.trimIndent()

        val packagePath = packageName.replace('.', '/')
        val outputFile = outputDir.file("$packagePath/$className.kt").get().asFile
        outputFile.parentFile.mkdirs()
        outputFile.writeText(fileContent)
    }

    fun getCommitCount(execOperations: ExecOperations): String = try {
        runCommand(execOperations, "git rev-list --count HEAD")
    } catch (e: Exception) {
        println("Error getting commit count: ${e.message}")
        "0"
    }

    fun getGitSha(execOperations: ExecOperations): String = try {
        runCommand(execOperations, "git rev-parse --short HEAD")
    } catch (e: Exception) {
        println("Error getting git sha: ${e.message}")
        "0"
    }
}