docker multistage build 失败，带有多个 --build-arg

Question

我正在使用这个 Dockerfile

ARG IMAGE_ONE
FROM ${IMAGE_ONE}
RUN cat /etc/debian_version

ARG IMAGE_TWO
FROM ${IMAGE_TWO}
RUN cat /etc/debian_version

但它失败了，因为它没有使用第二个 var IMAGE_TWO:

$ docker build --no-cache --build-arg IMAGE_ONE=debian:7 --build-arg IMAGE_TWO=debian:8 .
Sending build context to Docker daemon  2.048kB
Step 1/6 : ARG IMAGE_ONE
Step 2/6 : FROM ${IMAGE_ONE}
 ---> 90c038768099
Step 3/6 : RUN cat /etc/debian_version
 ---> Running in f842d9cf4f17
7.11
Removing intermediate container f842d9cf4f17
 ---> 0f7f7afdd8a6
Step 4/6 : ARG IMAGE_TWO
 ---> Running in ed3d36f2f9cb
Removing intermediate container ed3d36f2f9cb
 ---> ae4ae3cabc02
Step 5/6 : FROM ${IMAGE_TWO}
 --->
Step 6/6 : RUN cat /etc/debian_version
 ---> Running in 6f1c165e2765
OCI runtime create failed: container_linux.go:296:
    starting container process caused "exec: \"/bin/sh\":
    stat /bin/sh: no such file or directory": unknown

Docker 版本：

$ docker --version
Docker version 17.12.0-ce, build c97c6d6

我的 Dockerfile 有问题还是 docker build 命令有误？

Answer 1

原因是因为IMAGE_TWO不在同一个范围检查这个 https://docs.docker.com/engine/reference/builder/#scope

基本上，ARG IMAGE_TWO 仍然是第一阶段的一部分，并且在该阶段结束时超出范围，不会成为第二阶段的一部分。

在开头声明参数允许 IMAGE_TWO 处于第二阶段。

ARG IMAGE_ONE
ARG IMAGE_TWO
FROM ${IMAGE_ONE}
RUN cat /etc/debian_version

FROM ${IMAGE_TWO}
RUN cat /etc/debian_version

docker build --build-arg=IMAGE_ONE=debian:7 --build-arg=IMAGE_TWO=debian:8 .