Alpine package install protocol error - docker

Question

I am trying to install git on alpine 3.6. It is failing with Protocol error in the first instance but works on the second instance. To be specific pcre and libcurl are not installed in first instance. Here's the log of what I am trying to do.
$ docker run -it alpine:3.6 /bin/sh
/ # apk --update add git
fetch http://dl-cdn.alpinelinux.org/alpine/v3.6/main/x86_64/APKINDEX.tar.gz
fetch http://dl-cdn.alpinelinux.org/alpine/v3.6/community/x86_64/APKINDEX.tar.gz
(1/6) Installing ca-certificates (20161130-r2)
(2/6) Installing libssh2 (1.8.0-r1)
(3/6) Installing libcurl (7.56.1-r0)
ERROR: libcurl-7.56.1-r0: Protocol error
(4/6) Installing expat (2.2.0-r1)
(5/6) Installing pcre (8.41-r0)
ERROR: pcre-8.41-r0: Protocol error
(6/6) Installing git (2.13.5-r0)
Executing busybox-1.26.2-r9.trigger
Executing ca-certificates-20161130-r2.trigger
2 errors; 24 MiB in 15 packages
/ # git
Error loading shared library libpcre.so.1: No such file or directory (needed by /usr/bin/git)
Error relocating /usr/bin/git: pcre_compile: symbol not found
Error relocating /usr/bin/git: pcre_exec: symbol not found
Error relocating /usr/bin/git: pcre_maketables: symbol not found
Error relocating /usr/bin/git: pcre_study: symbol not found
Error relocating /usr/bin/git: pcre_free: symbol not found
Installing pcre/git again works though.
/ # apk add pcre
(1/2) Installing libcurl (7.56.1-r0)
(2/2) Installing pcre (8.41-r0)
OK: 25 MiB in 17 packages
/ # git
usage: git [--version] [--help] [-C <path>] [-c name=value]
[--exec-path[=<path>]] [--html-path] [--man-path] [--info-path]
[-p | --paginate | --no-pager] [--no-replace-objects] [--bare]
[--git-dir=<path>] [--work-tree=<path>] [--namespace=<name>]
<command> [<args>]

Answer 1

I had this problem too (surprisingly, it was deterministic), and changing the mirror worked. For example, do:
$ echo "https://mirror.csclub.uwaterloo.ca/alpine/v3.7/main" >/etc/apk/repositories
$ echo "https://mirror.csclub.uwaterloo.ca/alpine/v3.7/community" >>/etc/apk/repositories
to change the mirror to the UWaterloo server. You can find the full list of mirrors here.