Docker：错误：无法满足的约束

Question

我正在尝试从https://docs.docker.com/compose/gettingstarted/构建 docker 映像示例。我收到了这个错误

Building web
Step 1/9 : FROM python:3.7-alpine
 ---> e854017db514
Step 2/9 : WORKDIR /code
 ---> Using cache
 ---> e15b6e62d8af
Step 3/9 : ENV FLASK_APP app.py
 ---> Using cache
 ---> 759c4bc8b254
Step 4/9 : ENV FLASK_RUN_HOST 0.0.0.0
 ---> Using cache
 ---> 6d40793f3089
Step 5/9 : RUN apk add --no-cache gcc musl-dev linux-headers
 ---> Running in 5e40bd670f1b
fetch http://dl-cdn.alpinelinux.org/alpine/v3.11/main/x86_64/APKINDEX.tar.gz
fetch http://dl-cdn.alpinelinux.org/alpine/v3.11/community/x86_64/APKINDEX.tar.gz
WARNING: Ignoring http://dl-cdn.alpinelinux.org/alpine/v3.11/main/x86_64/APKINDEX.tar.gz: Permission denied
WARNING: Ignoring http://dl-cdn.alpinelinux.org/alpine/v3.11/community/x86_64/APKINDEX.tar.gz: Permission denied
ERROR: unsatisfiable constraints:
  gcc (missing):
    required by: world[gcc]
  linux-headers (missing):
    required by: world[linux-headers]
  musl-dev (missing):
    required by: world[musl-dev]
ERROR: Service 'web' failed to build: The command '/bin/sh -c apk add --no-cache gcc musl-dev linux-headers' returned a non-zero code: 3

这是我的 Dockfile

FROM python:3.7-alpine
WORKDIR /code
ENV FLASK_APP app.py
ENV FLASK_RUN_HOST 0.0.0.0
RUN apk add --no-cache gcc musl-dev linux-headers
COPY requirements.txt requirements.txt
RUN pip install -r requirements.txt
COPY . .
CMD ["flask", "run"]

任何人都可以帮我解决这个错误吗？谢谢大家！！！

Answer 1

您要安装的软件包是否已移至其他注册表？

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有时，正在安装的软件包是从不同的注册表分支移动的。默认的 Docker Alpine 镜像仅设置了某些注册表。添加额外的注册表可以扩展您的安装选项 (YMMV)；我无法谈论与不同注册表分支相关的稳定性、安全性和/或风险。这个线程帮助了我。

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尝试失败&错误消息：

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\xe2\x9d\xaf docker run -it alpine sh                                                                                                                                                                 \n/ # apk update\nfetch http://dl-cdn.alpinelinux.org/alpine/v3.12/main/x86_64/APKINDEX.tar.gz\nfetch http://dl-cdn.alpinelinux.org/alpine/v3.12/community/x86_64/APKINDEX.tar.gz\nv3.12.0-175-g8b3334c57c [http://dl-cdn.alpinelinux.org/alpine/v3.12/main]\nv3.12.0-178-gb27c83e867 [http://dl-cdn.alpinelinux.org/alpine/v3.12/community]\nOK: 12749 distinct packages available\n/ # apk add cowsay\nERROR: unsatisfiable constraints:\n  cowsay (missing):\n    required by: world[cowsay]\n/ # \n\n

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1. 我们从输出中得到的第一条线索
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ERROR: unsatisfiable constraints:\n       cowsay (missing):\n       required by: world[cowsay]\n

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2. 输出的第二条线索
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日志中较早的部分

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fetch http://dl-cdn.alpinelinux.org/alpine/v3.12/main/x86_64/APKINDEX.tar.gz\nfetch http://dl-cdn.alpinelinux.org/alpine/v3.12/community/x86_64/APKINDEX.tar.gz\n

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解决方案

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3. 在 DuckDuckGo 上搜索package <package name>
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• 引导我访问 URL： https: //pkgs.org/download/cowsay
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我使用哪种类型的内存？

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• 答案可以在线索#2中找到 。x86_64
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在包页面上选择正确的链接。所以就我而言：

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• Alpine 测试 x86_64 > owsay-3.04-r0.apk
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阅读该页面上的信息，我在下载二进制文件下看到目前位于

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• http://dl-cdn.alpinelinux.org/alpine/edge/testing/x86_64/cowsay-3.04-r0.apk
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将此与线索 #2 进行比较，我发现 alpine 容器没有使用我想要安装的二进制文件引用注册表。

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成功 & TL;DR;

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通过向 docker alpine 容器添加额外的注册表，将以前未找到的包添加到 alpine。

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我将添加查找我想要安装的软件包所需的注册表（步骤#3）。在下面的代码块中，可以看到第三个注册表与第 3 部分中完成的研究中的 URL 的初始部分相匹配。我不想替换现有的注册表（线索#2），所以我再次设置了它们。我不知道这是否有必要，但我还是这么做了。

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ERROR: unsatisfiable constraints:\n       cowsay (missing):\n       required by: world[cowsay]\n

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Dockerfile 示例

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fetch http://dl-cdn.alpinelinux.org/alpine/v3.12/main/x86_64/APKINDEX.tar.gz\nfetch http://dl-cdn.alpinelinux.org/alpine/v3.12/community/x86_64/APKINDEX.tar.gz\n

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构建此文件后：

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$ docker run -it alpine sh\n/# apk update && apk add cowsay \\\n        --update-cache \\\n        --repository https://alpine.global.ssl.fastly.net/alpine/edge/community \\\n        --repository https://alpine.global.ssl.fastly.net/alpine/edge/main \\\n        --repository https://dl-3.alpinelinux.org/alpine/edge/testing\nfetch http://dl-cdn.alpinelinux.org/alpine/v3.12/main/x86_64/APKINDEX.tar.gz\nfetch http://dl-cdn.alpinelinux.org/alpine/v3.12/community/x86_64/APKINDEX.tar.gz\nv3.12.0-175-g8b3334c57c [http://dl-cdn.alpinelinux.org/alpine/v3.12/main]\nv3.12.0-178-gb27c83e867 [http://dl-cdn.alpinelinux.org/alpine/v3.12/community]\nOK: 12749 distinct packages available\nfetch https://dl-3.alpinelinux.org/alpine/edge/testing/x86_64/APKINDEX.tar.gz\nfetch https://alpine.global.ssl.fastly.net/alpine/edge/main/x86_64/APKINDEX.tar.gz\nfetch https://alpine.global.ssl.fastly.net/alpine/edge/community/x86_64/APKINDEX.tar.gz\n(1/3) Installing libbz2 (1.0.8-r1)\n(2/3) Installing perl (5.30.3-r2)\n(3/3) Installing cowsay (3.04-r0)\nExecuting busybox-1.31.1-r16.trigger\nOK: 43 MiB in 17 packages\n/ #\n

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