如何使curl在基于Java：8-jdk-alpine的Docker映像中可用并保持映像清洁？

问题描述

我们有运行curl命令的Java代码以获取某些结果。

We are having java code that runs curl command to fetch the some result.

我们已经构建了一个jar文件，并且jar文件执行得很好

We have built a jar file and the jar file executes fine

现在，当我们尝试对Java程序进行dokerize（使用jar）并在docker中运行该应用程序时，会出现以下错误：

Now, when we try to dokerize the java program (using jar) and run the application in docker we get this error:

errorjava.io.IOException: Cannot run program "curl": error=2, No such file or directory
    at java.lang.ProcessBuilder.start(ProcessBuilder.java:1048)
    at com.ps.api.common.CoreAPI_Spec.executeCoreAPI(CoreAPI_Spec.java:295)
    at com.ps.api.common.CoreAPI_Spec.getAccessTokens(CoreAPI_Spec.java:319)

使用的Dockerfile：

Dockerfile used :

FROM ubuntu:16.04
MAINTAINER niro;

# Install prerequisites
RUN apt-get update && apt-get install -y \
curl

FROM java:8-jdk-alpine
# Set the working directory to /app
WORKDIR /Users/******/Desktop/CoreAPI_Jar

# Copy the current directory contents into the container at /app
ADD *******_Automation-0.0.1-SNAPSHOT-jar-with-dependencies.jar ******_Automation-0.0.1-SNAPSHOT-jar-with-dependencies.jar

# Run app.py when the container launches
CMD ["java", "-jar", "******-0.0.1-SNAPSHOT-jar-with-dependencies.jar"]

推荐答案

您使用的Java基本映像是Alpine Linux one，并且还需要从那里下载curl软件包。这是我用于生产部署的Dockerfile。

The Java base image you are using is Alpine Linux one and curl package also needs to be downloaded from there. Here is Dockerfile I have used for Production deployments.

FROM openjdk:8-jre-alpine

RUN apk add --update \
    curl \
    && rm -rf /var/cache/apk/*

---

更新05 / 2019

从Alpine Linux 3.3开始，对于-no-cache 选项> apk 。它允许用户使用实时更新和使用的索引来安装软件包，而不是在本地缓存：

---

Update 05/2019

As of Alpine Linux 3.3 there exists a new --no-cache option for apk. It allows users to install packages with an index that is updated and used on-the-fly and not cached locally:

FROM openjdk:8-jre-alpine
    
RUN apk --no-cache add curl

这避免了使用-更新并在完成安装软件包后删除 / var / cache / apk / * 。

This avoids the need to use --update and remove /var/cache/apk/* when done installing packages.

参考-
，谢谢@Daniel的评论。

Reference -https://github.com/gliderlabs/docker-alpine/blob/master/docs/usage.md and Thank you @Daniel for the comment.

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