dotnet-install.sh doesn't work on Alpine Linux v3.7

Steps to reproduce

docker run -it alpine:latest

# in container
apk update
apk add curl bash

curl -O https://raw.githubusercontent.com/dotnet/cli/master/scripts/obtain/dotnet-install.sh
chmod 777 dotnet-install.sh
./dotnet-install.sh

# errors
dotnet_install: Error: Unable to locate libunwind. Install libunwind to continue
dotnet_install: Error: Unable to locate libssl. Install libssl to continue
dotnet_install: Error: Unable to locate libicu. Install libicu to continue
dotnet_install: Error: Unable to locate libcurl. Install libcurl to continue

apk add libunwind-dev openssl-dev icu-libs curl-dev
./dotnet-install.sh


# same errors
dotnet_install: Error: Unable to locate libunwind. Install libunwind to continue
dotnet_install: Error: Unable to locate libssl. Install libssl to continue
dotnet_install: Error: Unable to locate libicu. Install libicu to continue
dotnet_install: Error: Unable to locate libcurl. Install libcurl to continue

Expected behavior

it installs dotnet.

Actual behavior

it doesn’t install dotnet. Reason is we are using /sbin/ldconfig, which on alpine does not locate the installed libs (although i can find all of these under /usr/bin). According to maintainers in alpine’s IRC channel (cc @ncopa), this script is not meant to locate the libs reliably (but its purpose is to create some symlinks). The correct way is to use scanelf -qS /usr/lib | grep libunwind etc.

Workaround

Manually install dotnet from tarball as described here: https://github.com/PowerShell/PowerShell/pull/6367#issuecomment-372765035

Environment data

alpine linux 3.7

[johnbeisner]

@omajid “Perhaps we should add a flag to dotnet-install.sh to not check for pre-requisites” - try “export DOTNET_INSTALL_SKIP_PREREQS=1”

[ghost]

@janvorli, for your info. I spent sometime chatting with Alpine packaging folks to know how they see ldconfig, they gave me the above mentioned pointers (with explanation from me). The proposal in the linked / duplicated issue can work, but IMO can be revised a bit based on how other products requiring ldconfig have managed to support Alpine. Thanks!