docker - 在多阶段 Dockerfile : ARG before FROM not substituted 中共享变量

Question

我正在为 darshan utils 编写一个多阶段 Dockerfile :

ARG DARSHAN_VER=3.1.6

FROM fedora:29 as build
RUN dnf install -y \
        gcc \
        make \
        bzip2 bzip2-devel zlib zlib-devel
RUN curl -O "ftp://ftp.mcs.anl.gov/pub/darshan/releases/darshan-${DARSHAN_VER}.tar.gz" \
    && tar ...


FROM fedora:29
COPY --from=build "/usr/local/darshan-${DARSHAN_VER}" "/usr/local/darshan-${DARSHAN_VER}"
...

我用 docker build -t darshan-util:3.6.1 . 构建它，我得到的错误是:

Step 5/10 : RUN curl -O "ftp://ftp.mcs.anl.gov/pub/darshan/releases/darshan-${DARSHAN_VER}.tar.gz"     && tar ...

 ---> Running in 9943cce1669c
  % Total    % Received % Xferd  Average Speed   Time    Time     Time  Current
...
curl: (78) RETR response: 550
The command '/bin/sh -c curl -O "ftp://ftp.mcs.anl.gov/pub/darshan/releases/darshan-${DARSHAN_VER}.tar.gz"     && tar ...' returned a non-zero code: 78

我想在两个阶段重用相同的 ARG，以便我可以只定义一次默认构建变量。
如果我在两个阶段都复制 ARG，就在两个 FROM 的下方，它会正确构建。

使用默认值定义“全局”多级 ARG 变量的正确方法是什么？

Answer 1

ARG 仅在单个镜像的构建阶段持续。
对于多级，通过简单地说明更新 ARG:

ARG DARSHAN_VER

在您的 FROM 指令之后。

参见 https://docs.docker.com/engine/reference/builder/#arg

ARG DARSHAN_VER=3.1.6

FROM fedora:29 as build
ARG DARSHAN_VER
RUN dnf install -y \
        gcc \
        make \
        bzip2 bzip2-devel zlib zlib-devel
RUN curl -O "ftp://ftp.mcs.anl.gov/pub/darshan/releases/darshan-${DARSHAN_VER}.tar.gz" \
    && tar ...


FROM fedora:29
ARG DARSHAN_VER
COPY --from=build "/usr/local/darshan-${DARSHAN_VER}" "/usr/local/darshan-${DARSHAN_VER}"
...