=> ERROR [2/3] RUN apk --no-cache add dnsmasq nginx

[PhantomLord72]

My pc is behind a corporate proxy, windows 10, all images are pulled correctly, but after, the installation breaks with the error in the subject follwed by:
fetch https://dl-cdn.alpinelinux.org/alpine/v3.15/main/x86_64/APKINDEX.tar.gz
#6 21.47 WARNING: Ignoring https://dl-cdn.alpinelinux.org/alpine/v3.15/main: network error (check Internet connection and firewall)
#6 21.47 fetch https://dl-cdn.alpinelinux.org/alpine/v3.15/community/x86_64/APKINDEX.tar.gz
#6 42.54 WARNING: Ignoring https://dl-cdn.alpinelinux.org/alpine/v3.15/community: network error (check Internet connection and firewall)
#6 42.54 ERROR: unable to select packages:
#6 42.54 dnsmasq (no such package):
#6 42.54 required by: world[dnsmasq]
#6 42.54 nginx (no such package):
#6 42.54 required by: world[nginx]

failed to solve: rpc error: code = Unknown desc = executor failed running [/bin/sh -c apk --no-cache add dnsmasq nginx]: exit code: 2

[PhantomLord72]

Solved by myself after an half day:
please update proxy/Dockerfile :

ENV HTTP_PROXY http://x.x.x.x:yyy/
ENV HTTPS_PROXY http://x.x.x.x:yyy/
ENV NO_PROXY localhost,127.0.0.1,and so on...