Docker 构建：如何获得完整的 RUN 命令输出？

Question

更新：这个问题用 MVRE 重构。

有没有办法可以从使用 docker build 构建的 Dockerfile 中查看完整的 RUN 命令？ 例如。如果我的 Dockerfile 有语句：

# Dockerfile
FROM alpine:3.7 as base
RUN echo "this is the song that doesn't end. Yes it goes on and on, my friends. Some people started singing it not knowing what it was, and they'll continue singing it forever just because..."

...有没有办法可以看到完整的命令，即echo "this is the song that doesn't end. Yes it goes on and on, my friends. Some people started singing it not knowing what it was, and they'll continue singing it forever just because..." 以及运行该命令的完整输出？

我使用 docker build kit 构建（我不希望禁用它），默认情况下，它会折叠输出，并截断相对于终端宽度执行的命令，最终可能看起来像这样：

$ docker build --no-cache -t tmp:tmp .
[+] Building 16.2s (6/6) FINISHED
 => [internal] load build definition from Dockerfile                                 0.1s
 => => transferring dockerfile: 281B                                                 0.0s
 => [internal] load .dockerignore                                                    0.2s
 => => transferring context: 2B                                                      0.0s
 => [internal] load metadata for docker.io/library/alpine:3.7                        0.0s
 => CACHED [1/2] FROM docker.io/library/alpine:3.7                                   0.0s
 => [2/2] RUN echo "this is the song that doesn't end. Yes it goes on and on, my fr  2.0s
 => exporting to image                                                              13.9s
 => => exporting layers                                                              0.4s
 => => writing image sha256:d72d9f0e36f38227e2a28dce31781dc9b6089b01cf5645c70f33b2  13.5s
 => => naming to docker.io/library/tmp:tmp                                           0.0s

...即命令和它的输出都被截断/折叠。

This article 表示 docker inspect 应该用于此目的，在我的情况下：docker inspect tmp:tmp，我的答案将在输出的 $[0].Config.Cmd 部分，但该部分不包含相关资料：

$ docker inspect tmp:tmp
[
    {
        ...
        "Config": {
            ...
            "Cmd": [
                "/bin/sh"
            ],
            ...

...docker inspect 命令的任何其他部分也不包含相关信息（在我的示例中为 cmake 语句）。

This article 建议对docker build 使用--progress plain 选项。这会展开命令的输出，但它仍然会截断命令本身，例如：

$ docker build --progress plain --no-cache -t tmp:tmp .
#1 [internal] load build definition from Dockerfile
#1 transferring dockerfile: 44B done
#1 DONE 0.0s

#2 [internal] load .dockerignore
#2 transferring context: 2B done
#2 DONE 0.1s

#3 [internal] load metadata for docker.io/library/alpine:3.7
#3 DONE 0.0s

#4 [1/2] FROM docker.io/library/alpine:3.7
#4 CACHED

#5 [2/2] RUN echo "this is the song that doesn't end. Yes it goes on and on...
#5 1.542 this is the song that doesn't end. Yes it goes on and on, my friends. Some people
 started singing it not knowing what it was, and they'll continue singing it forever just
because...
#5 DONE 2.1s

#6 exporting to image
#6 exporting layers
#6 exporting layers 0.7s done
#6 writing image sha256:0ce39b23377d91e47e7aa9b4e10e50d5a62a4ef9ec281f1b3e244e4b66a17d02
#6 writing image sha256:0ce39b23377d91e47e7aa9b4e10e50d5a62a4ef9ec281f1b3e244e4b66a17d02 1
3.3s done
#6 naming to docker.io/library/tmp:tmp done
#6 DONE 14.0s

有没有办法可以查看 Dockerfile RUN 语句执行的完整（未截断）命令（以及命令的未折叠输出）？

我执行docker history的输出：

$ docker history tmp:tmp
IMAGE               CREATED             CREATED BY                                      SIZE                COMMENT
0ce39b23377d        3 minutes ago       RUN /bin/sh -c echo "this is the song that d…   0B                  buildkit.dockerfile.v0
<missing>           2 years ago         /bin/sh -c #(nop)  CMD ["/bin/sh"]              0B
<missing>           2 years ago         /bin/sh -c #(nop) ADD file:aa17928040e31624c…   4.21MB

Answer 1

设置 env-var PROGRESS_NO_TRUNC=1 和 --progress plain 就可以了：

$ PROGRESS_NO_TRUNC=1 docker build --progress plain --no-cache -t tmp:tmp .
#1 [internal] load .dockerignore
#1 sha256:0c3d9a77560c6997674ff903c1fd8166c2b0a0c56b8267c8919f9435df2b6360
#1 transferring context: 0.0s
#1 transferring context: 2B 0.0s done
#1 DONE 0.2s

#2 [internal] load build definition from Dockerfile
#2 sha256:637986daa013bdd36af757aa03cf8b23447a85ed9e3e103fda6234a9d97332cd
#2 transferring dockerfile: 44B 0.1s done
#2 DONE 0.2s

#3 [internal] load metadata for docker.io/library/alpine:3.7
#3 sha256:d05d2c4bcea3dce001a657515352ca6040d02fcc707293d5f7167602950d71ce
#3 DONE 0.0s

#4 [1/2] FROM docker.io/library/alpine:3.7
#4 sha256:c139e859151268321f8b3d9af4bf0195aab52a1b66880ee4294469151c73bfb9
#4 CACHED

#5 [2/2] RUN echo "this is the song that doesn't end. Yes it goes on and on, my friends. S
ome people started singing it not knowing what it was, and they'll continue singing it for
ever just because..."
#5 sha256:63a60e7b5a4ce0944e5135780a681e85c9fc52a776b498fcf0652f563bc0c470
#5 1.381 this is the song that doesn't end. Yes it goes on and on, my friends. Some people
 started singing it not knowing what it was, and they'll continue singing it forever just
because...
#5 DONE 1.7s

#6 exporting to image
#6 sha256:e8c613e07b0b7ff33893b694f7759a10d42e180f2b4dc349fb57dc6b71dcab00
#6 exporting layers
#6 exporting layers 0.2s done
#6 writing image sha256:523ddeb4ae29e8f8bbd9e346a07d980024e58d867222ed3d30d552587df72685 0
.0s done
#6 naming to docker.io/library/tmp:tmp 0.0s done
#6 DONE 0.2s

RUN 语句本身以及执行该语句的输出都完整呈现。