Docker构建Kotlin Gradle应用失败（exit code1）求Dockerfile修改方案

我在IntelliJ中创建了一个Kotlin应用，配置如下：

• 名称：ktdocker
• 构建系统：Gradle
• JDK：corretto-20
• Gradle DSL：Kotlin
• GroupID：com.demo

尝试容器化到Docker时，出现以下错误：

=> ERROR [builder  9/11] RUN ./gradlew dependencies --no-daemon
ERROR: failed to solve: process "/bin/sh -c ./gradlew dependencies --no-daemon" did not complete successfully: exit code: 1

构建镜像使用命令：

docker build --tag ktdocker .

系统环境：Windows 11，目标是创建可在Google Cloud Run运行的Dockerfile。

相关文件内容 #

Dockerfile

# Use a lightweight Java runtime image
FROM eclipse-temurin:17-jdk-alpine as builder

# Set the working directory
WORKDIR /app

# Install necessary tools
RUN apk add --no-cache bash curl git dos2unix

# Copy Gradle wrapper and project files
COPY gradlew ./
COPY gradle ./gradle
COPY build.gradle.kts ./
COPY settings.gradle.kts ./

# Fix line endings and permissions for Gradle wrapper
RUN dos2unix gradlew && chmod +x gradlew

# Download Gradle dependencies
RUN ./gradlew dependencies --no-daemon

# Copy the application source code
COPY src ./src

# Build the application
RUN ./gradlew build --no-daemon

# Use a lightweight Java runtime image for the final build
FROM eclipse-temurin:17-jre-alpine

# Set the working directory
WORKDIR /app

# Copy the jar file from the build stage
COPY --from=builder /app/build/libs/*.jar app.jar

# Expose the application port (Cloud Run uses PORT)
EXPOSE 8080

# Command to run the application
ENTRYPOINT ["java", "-jar", "app.jar"]

Main.kt

package com.demo

fun main() {
    val name = "Kotlin"
    println("Hello, " + name + "!")

    for (i in 1..5) {
        println("i = $i")
    }
}

build.gradle.kts

plugins {
    kotlin("jvm") version "2.0.20"
}

group = "com.demo"
version = "1.0-SNAPSHOT"

repositories {
    mavenCentral()
}

dependencies {
    testImplementation(kotlin("test"))
}

tasks.test {
    useJUnitPlatform()
}
kotlin {
    jvmToolchain(20)
}

./gradlew -v

------------------------------------------------------------
Gradle 8.8
------------------------------------------------------------

Build time:   2024-05-31 21:46:56 UTC
Revision:     4bd1b3d3fc3f31db5a26eecb416a165b8cc36082

Kotlin:       1.9.22
Groovy:       3.0.21
Ant:          Apache Ant(TM) version 1.10.13 compiled on January 4 2023
JVM:          23.0.1 (Oracle Corporation 23.0.1+11-39)
OS:           Windows 11 10.0 amd64

需要针对以下关键问题修改Dockerfile：

1. 统一JDK版本（核心问题） #

build.gradle.kts中指定了jvmToolchain(20)，但Docker构建阶段使用的是JDK 17镜像，版本不匹配会导致Gradle依赖下载或编译失败。

修改方式：将构建阶段的基础镜像替换为JDK 20版本，推荐使用与本地一致的Amazon Corretto：

FROM amazoncorretto:20-alpine-jdk as builder

2. 合并Gradle命令优化构建流程 #

单独执行./gradlew dependencies容易因网络或缓存问题失败，建议直接将依赖下载合并到构建步骤，同时跳过测试加快构建速度：

修改方式：

# 移除单独的dependencies命令，替换为以下构建命令
COPY src ./src
RUN ./gradlew build --no-daemon --no-build-cache --refresh-dependencies -x test

3. 同步运行阶段的JRE版本 #

编译后的字节码需要对应版本的JRE运行，因此最终镜像也要使用JRE 20：

FROM amazoncorretto:20-alpine-jre

4. 简化工具安装与换行符处理 #

无需安装curl和git，仅保留必要工具；同时确保Gradle wrapper配置文件的换行符也被修复：

RUN apk add --no-cache bash dos2unix
RUN dos2unix gradlew gradle/wrapper/gradle-wrapper.properties && chmod +x gradlew

5. 适配Google Cloud Run环境变量 #

Cloud Run会自动注入PORT环境变量，添加环境变量声明以适配平台规范：

ENV PORT=8080
EXPOSE ${PORT}

修改后的完整Dockerfile #

# 使用与项目匹配的JDK 20镜像作为构建阶段
FROM amazoncorretto:20-alpine-jdk as builder

WORKDIR /app

# 安装必要工具
RUN apk add --no-cache bash dos2unix

# 复制Gradle相关文件
COPY gradlew ./
COPY gradle ./gradle
COPY build.gradle.kts ./
COPY settings.gradle.kts ./

# 修复换行符和执行权限
RUN dos2unix gradlew gradle/wrapper/gradle-wrapper.properties && chmod +x gradlew

# 复制源码并构建（跳过测试，确保依赖下载）
COPY src ./src
RUN ./gradlew build --no-daemon --no-build-cache --refresh-dependencies -x test

# 运行阶段使用匹配的JRE 20镜像
FROM amazoncorretto:20-alpine-jre

WORKDIR /app

# 复制构建好的jar包
COPY --from=builder /app/build/libs/*.jar app.jar

# 适配Cloud Run的PORT环境变量
ENV PORT=8080
EXPOSE ${PORT}

# 运行应用
ENTRYPOINT ["java", "-jar", "app.jar"]

内容的提问来源于stack exchange，提问作者Europa