我正在尝试在rhel 7上运行一个简单的高山docker映像，但是当我运行apk更新时却卡在此错误中：
fetch http://dl-cdn.alpinelinux.org/alpine/v3.10/main/x86_64/APKINDEX.tar.gz
ERROR: http://dl-cdn.alpinelinux.org/alpine/v3.10/main: could not connect to server (check repositories file)
WARNING: Ignoring APKINDEX.00740ba1.tar.gz: No such file or directory
fetch http://dl-cdn.alpinelinux.org/alpine/v3.10/community/x86_64/APKINDEX.tar.gz
ERROR: http://dl-cdn.alpinelinux.org/alpine/v3.10/community: could not connect to server (check repositories file)
WARNING: Ignoring APKINDEX.d8b2a6f4.tar.gz: No such file or directory
2 errors; 14 distinct packages available
我运行以下命令：
docker run -it --rm --env="http_proxy=http://127.0.0.1:3128" alpine /bin/sh
apk update
我在虚拟机中的ssh隧道代理后面。 我已经设置了/etc/docker/daemon_config.json，/etc/systemd/system/docker.service.d/http.proxy.d，环境变量和dns。
我该怎么办？