Dockerfile覆盖ARG值

Question

我有一个Dockerfile有Scala和SBT如下：如果我想用这个作为我的基本图像

# Scala and sbt Dockerfile 
# Scala and SBT forked from: https://github.com/hseeberger/scala-sbt 
# Adds Docker client installation additionally 

# Pull base image 
FROM openjdk:$JAVA_VERSION 

ARG SCALA_VERSION 
ARG SBT_VERSION 

# Scala expects this file 
RUN touch /usr/lib/jvm/java-$JAVA_VERSION-openjdk-amd64/release 

# Install Scala 
## Piping curl directly in tar 
RUN \ 
    curl -fsL http://downloads.typesafe.com/scala/$SCALA_VERSION/scala-$SCALA_VERSION.tgz | tar xfz - -C /root/ && \ 
    echo >> /root/.bashrc && \ 
    echo 'export PATH=~/scala-$SCALA_VERSION/bin:$PATH' >> /root/.bashrc 

# Install sbt 
RUN \ 
    curl -L -o sbt-$SBT_VERSION.deb http://dl.bintray.com/sbt/debian/sbt-$SBT_VERSION.deb && \ 
    dpkg -i sbt-$SBT_VERSION.deb && \ 
    rm sbt-$SBT_VERSION.deb && \ 
    apt-get update && \ 
    apt-get install sbt && \ 
    sbt sbtVersion 

现在，我有以下问题：

1. 我可以在我的新Dockerfile中覆盖ARG参数，它将使用上面那个作为基础图像吗？

Answer 1

每个Dockerfile都会生成一个不可变的图像。所以你需要先建立一个特定的基础图像，然后建立你自己的FROM它。

你可以采取这种做法：

Dockerfile.base：

# Scala and sbt Dockerfile 
# Scala and SBT forked from: https://github.com/hseeberger/scala-sbt 
# Adds Docker client installation additionally 

# Pull base image 
ARG JAVA_VERSION 
FROM openjdk:$JAVA_VERSION 

ARG SCALA_VERSION 
ARG SBT_VERSION 

# Scala expects this file 
RUN touch /usr/lib/jvm/java-$JAVA_VERSION-openjdk-amd64/release 

# Install Scala 
## Piping curl directly in tar 
RUN \ 
    curl -fsL http://downloads.typesafe.com/scala/$SCALA_VERSION/scala-$SCALA_VERSION.tgz | tar xfz - -C /root/ && \ 
    echo >> /root/.bashrc && \ 
    echo 'export PATH=~/scala-$SCALA_VERSION/bin:$PATH' >> /root/.bashrc 

# Install sbt 
RUN \ 
    curl -L -o sbt-$SBT_VERSION.deb http://dl.bintray.com/sbt/debian/sbt-$SBT_VERSION.deb && \ 
    dpkg -i sbt-$SBT_VERSION.deb && \ 
    rm sbt-$SBT_VERSION.deb && \ 
    apt-get update && \ 
    apt-get install sbt && \ 
    sbt sbtVersion 

你的孩子Dockerfile Dockerfile.mine：

ARG JAVA_VERSION 
ARG SCALA_VERSION 
ARG SBT_VERSION 
FROM basejava:java-$JAVA_VERSION-scala-$SCALA_VERSION-sbt-$SBT_VERSION 
# Your app stuf here 
# ... 
# ... 

构建例如：

export JAVA_VERSION=latest 
export SCALA_VERSION=1.8 
export SBT_VERSION=0.13.9 
docker build . \ 
    -f Dockerfile.base \ 
    --build-arg JAVA_VERSION=$JAVA_VERSION \ 
    --build-arg SCALA_VERSION=$SCALA_VERSION \ 
    --build-arg SBT_VERSION=$SBT_VERSION \ 
    -t basejava:java-$JAVA_VERSION-scala-$SCALA_VERSION-sbt-$SBT_VERSION 

docker build . \ 
    -f Dockerfile.mine \ 
    --build-arg JAVA_VERSION=latest \ 
    --build-arg SCALA_VERSION=1.8 \ 
    --build-arg SBT_VERSION=0.13.9 
    -t myjava:java-$JAVA_VERSION-scala-$SCALA_VERSION-sbt-$SBT_VERSION 

---

方法2，ONBUILD，由zigarn提及。

Dockerfile.base：

# Scala and sbt Dockerfile 
# Scala and SBT forked from: https://github.com/hseeberger/scala-sbt 
# Adds Docker client installation additionally 

# Pull base image 
ONBUILD ARG JAVA_VERSION 
FROM openjdk:$JAVA_VERSION 

ONBUILD ARG SCALA_VERSION 
ONBUILD ARG SBT_VERSION 

# Scala expects this file 
ONBUILD RUN touch /usr/lib/jvm/java-$JAVA_VERSION-openjdk-amd64/release 

# Install Scala 
## Piping curl directly in tar 
ONBUILD RUN \ 
    curl -fsL http://downloads.typesafe.com/scala/$SCALA_VERSION/scala-$SCALA_VERSION.tgz | tar xfz - -C /root/ && \ 
    echo >> /root/.bashrc && \ 
    echo 'export PATH=~/scala-$SCALA_VERSION/bin:$PATH' >> /root/.bashrc 

# Install sbt 
ONBUILD RUN \ 
    curl -L -o sbt-$SBT_VERSION.deb http://dl.bintray.com/sbt/debian/sbt-$SBT_VERSION.deb && \ 
    dpkg -i sbt-$SBT_VERSION.deb && \ 
    rm sbt-$SBT_VERSION.deb && \ 
    apt-get update && \ 
    apt-get install sbt && \ 
    sbt sbtVersion 

你的孩子Dockerfile.mine

FROM basejava 
# Base ONLBUILD instructions are automatically inserted here. 
# Your app stuf here 
# ... 
# ... 

体形：

docker build . -f Dockerfile.base -t basejava 

export JAVA_VERSION=latest 
export SCALA_VERSION=1.8 
export SBT_VERSION=0.13.9 
docker build . \ 
    -f Dockerfile.mine \ 
    --build-arg JAVA_VERSION=$JAVA_VERSION \ 
    --build-arg SCALA_VERSION=$SCALA_VERSION \ 
    --build-arg SBT_VERSION=$SBT_VERSION \ 
    -t myjava:java-$JAVA_VERSION-scala-$SCALA_VERSION-sbt-$SBT_VERSION 

Answer 2

ARG值是在构建时定义的。
一旦你的基本映像建，你不能只是改变--build-arg再弄SCALA_VERSION您的最终图像中（或你必须在你重新安装新Dockerfile）

本Dockerfile是像其他Dockerfile模板。
您可以使用ONBUILD instruction在构建其他图像时使用此图像作为基础图像来有效地进行安装。