Dockerfile构建时命令执行失败，手动执行却正常

我尝试构建的Dockerfile内容如下：

FROM node:18-alpine

RUN apk add --no-cache yarn python3 make gcc g++
ADD start.sh /
RUN chmod +x /start.sh

CMD ["/start.sh"]

但Docker构建时返回如下错误：

root@VM:~/playground/docker/web# docker build .
[+] Building 10.4s (6/8)                                                                                                                                                                    docker:default
 => [internal] load build definition from Dockerfile                                                                                                                                                  0.0s
 => => transferring dockerfile: 163B                                                                                                                                                                  0.0s
 => [internal] load metadata for docker.io/library/node:18-alpine                                                                                                                                     0.0s
 => [internal] load .dockerignore                                                                                                                                                                     0.0s
 => => transferring context: 2B                                                                                                                                                                       0.0s
 => CACHED [1/4] FROM docker.io/library/node:18-alpine                                                                                                                                                0.0s
 => ERROR [2/4] RUN apk add --no-cache yarn python3 make gcc g++                                                                                                                                     10.3s
 => [internal] load build context                                                                                                                                                                     0.0s
 => => transferring context: 29B                                                                                                                                                                      0.0s
------
 > [2/4] RUN apk add --no-cache yarn python3 make gcc g++:
0.270 fetch https://dl-cdn.alpinelinux.org/alpine/v3.20/main/x86_64/APKINDEX.tar.gz
5.275 fetch https://dl-cdn.alpinelinux.org/alpine/v3.20/community/x86_64/APKINDEX.tar.gz
5.275 WARNING: fetching https://dl-cdn.alpinelinux.org/alpine/v3.20/main: temporary error (try again later)
10.28 WARNING: fetching https://dl-cdn.alpinelinux.org/alpine/v3.20/community: temporary error (try again later)
10.28 ERROR: unable to select packages:
10.28   g++ (no such package):
10.28     required by: world[g++]
10.28   gcc (no such package):
10.28     required by: world[gcc]
10.28   make (no such package):
10.28     required by: world[make]
10.28   python3 (no such package):
10.28     required by: world[python3]
10.28   yarn (no such package):
10.28     required by: world[yarn]
------
Dockerfile:3
--------------------
   1 |     FROM node:18-alpine
   2 |     
   3 | >>> RUN apk add --no-cache yarn python3 make gcc g++
   4 |     ADD start.sh /
   5 |     RUN chmod +x /start.sh
--------------------
ERROR: failed to solve: process "/bin/sh -c apk add --no-cache yarn python3 make gcc g++" did not complete successfully: exit code: 5

该步骤执行失败，但我通过docker run -it node:18-alpine /bin/sh进入容器后执行相同命令却成功。已排除间歇性网络问题，请问为何同一命令在docker build中失败，手动执行却正常？

可能的原因及解决办法 #

• 镜像缓存失效：构建过程复用了缓存的node:18-alpine镜像，该镜像内的APK源索引已过期，无法匹配到对应包。而手动运行容器时，可能拉取了最新基础镜像，或进入容器后自动刷新了索引。解决方式：构建时添加--no-cache参数跳过缓存，命令为docker build --no-cache .
• 构建与运行的网络环境差异：Docker构建时使用的网络和容器运行时网络存在差异（比如主机防火墙、代理规则限制了构建过程的网络访问）。可以尝试用host网络构建：docker build --network host .
• 缺少APK索引更新步骤：缓存镜像内的APK索引未更新，手动进入容器时可能隐式执行了索引刷新，而构建时直接安装导致找不到包。修改Dockerfile，先执行apk update再安装：

FROM node:18-alpine

RUN apk update && apk add --no-cache yarn python3 make gcc g++
ADD start.sh /
RUN chmod +x /start.sh

CMD ["/start.sh"]

内容的提问来源于stack exchange，提问作者Mit94