Could not find a valid Docker environment when using Gradle Shared Build Service (`ClassNotFoundException` when loading strategies)

Discussed in https://github.com/testcontainers/testcontainers-java/discussions/9034

^{Originally posted by debapgithub July 30, 2024}
Hi,

I am new to testcontainers and setting up for a gradle service where I wanted to achieve the following in sequence.

When gradle build command will run : ./gradlew clean build

1. MySql Testcontainer should start
2. DB migrations should apply against the testcontainer DB
3. generateJooq task should execute against the testcontainer DB
4. Run the integration tests against testcontainer
5. At the end of the build process, testcotnainer should stop automatically.

I have tried starting MySql testcontainer as a gradle task and I was able to execute the following tasks properly except one issue due to which I have decided to switch to another approach where I can start the MySql testcontainer as a gradle Shared service so that it will automaticllay manage the testcontainer lifecycle.

Here is the code which will start the testcontainer as a gradle shared service and it worked fine as well. But next day when I tried running the gradle command, I started getting the below error.
Error

* What went wrong:
Execution failed for task ':startMySQLContainer'.
> Failed to create service 'mysqlContainerService'.
   > Could not create an instance of type MySQLContainerService.
      > Could not find a valid Docker environment. Please see logs and check configuration

* Try:
> Run with --stacktrace option to get the stack trace.
> Run with --info or --debug option to get more log output.
> Run with --scan to get full insights.
> Get more help at https://help.gradle.org.

Gradle Code

import org.testcontainers.containers.MySQLContainer;
import org.gradle.api.services.BuildService
import org.gradle.api.services.BuildServiceParameters

buildscript {
    repositories {
        maven {
            name repoName
            url repoUrl
            credentials() {
                username = repoUsername
                password = repoPassword
            }
        }
    }

    dependencies {
        classpath "org.testcontainers:testcontainers:${dependencyManagement.importedProperties['testcontainers.version']}"
        classpath "org.testcontainers:mysql:${dependencyManagement.importedProperties['testcontainers.version']}"
        classpath "com.mysql:mysql-connector-j:${dependencyManagement.importedProperties['mysql.version']}"
    }
}


// Here we register service for providing our database during the build.
gradle.sharedServices.registerIfAbsent('mysqlContainerService', MySQLContainerService) { spec ->
    spec.parameters.databaseSchemaName.set(project.ext.databaseSchemaName)
}

/**
 * Build service for providing database container.
 */
abstract class MySQLContainerService implements BuildService<MySQLContainerService.Params>, AutoCloseable {
    interface Params extends BuildServiceParameters {
        Property<String> getDatabaseSchemaName()
    }
    private final MySQLContainer mysqlContainer;

    @javax.inject.Inject
    MySQLContainerService(Params params) {
        // Services are initialized lazily, on first request to them, so we start container immediately.
        long startTime = System.currentTimeMillis()
        println("DB Schema Name: ${params.getDatabaseSchemaName().get()}")
        mysqlContainer = new MySQLContainer(MySQLContainer.IMAGE).withDatabaseName(params.getDatabaseSchemaName().get())
        mysqlContainer.start()
        long duration = System.currentTimeMillis() - startTime
        println("MySQL Testcontainer Started successfully with URL: ${mysqlContainer.getJdbcUrl()}. Total time taken: ${duration} ms")
    }

    String getJdbcUrl() {
        return mysqlContainer.getJdbcUrl()
    }

    String getUsername() {
        return mysqlContainer.getUsername()
    }

    String getPassword() {
        return mysqlContainer.getPassword()
    }

    String getDriverClassName() {
        return mysqlContainer.getDriverClassName()
    }


    @Override
    void close() {
        // Ensure to stop container in the end
        if (mysqlContainer != null) {
            try {
                mysqlContainer.stop()
                println("MySQL container stopped successfully.")
            } catch (Exception e) {
                println("Failed to stop MySQL container: ${e.message}")
            }
        } else {
            println("MySQL container is already null (was not started).")
        }
    }
}

tasks.register('startMySQLContainer') {
    doLast {
        gradle.sharedServices.getRegistrations().getByName('mysqlContainerService')
    }
}

// Ensure the integrationTest uses the same container and stops it after
tasks.named('integrationTest').configure {
    dependsOn 'startMySQLContainer'
    doFirst {
        def service = gradle.sharedServices.getRegistrations().getByName('mysqlContainerService').service.get()
        systemProperty 'spring.datasource.url', service.getJdbcUrl()
        systemProperty 'spring.datasource.username', service.getUsername()
        systemProperty 'spring.datasource.password', service.getPassword()
        systemProperty 'spring.datasource.driver-class-name', service.getDriverClassName()
    }

    doLast {
        systemProperties.remove('spring.datasource.url')
        systemProperties.remove('spring.datasource.username')
        systemProperties.remove('spring.datasource.password')
        systemProperties.remove('spring.datasource.driver-class-name')
    }
}

Not sure whats going wrong and how it worked first time when I did this code.

Thanks in advance!!

-Deba

レポートに示されている Gradle buildscript と MySQLContainerService から始め、次に --stacktrace を付けて :startMySQLContainer を再現し、ClassNotFoundException と Docker 環境の検出ログを調査します。共有サービスの classpath または strategy loading が実行ごとに異なる理由を特定し、報告された build sequence に対する文書化またはテスト済みの解決策を確認できれば完了です。