I have weird issue now with mix local.rebar --force timing out semi-randomly when I run it from within docker container.

I am attaching a Dockerfile recipe below, that fails to build on the last RUN

FROM buildpack-deps:stretch                                                                                                                                              
                                                                                                                                                                         
USER root                                                                                                                                                                
                                                                                                                                                                         
ENV LANG=C.UTF-8                                                                                                                                                         
ENV HOME=/root                                                                                                                                                           
                                                                                                                                                                         
RUN apt-get update && apt-get install -y --no-install-recommends apt-utils                                                                                               
                                                                                                                                                                         
#                                                                                                                                                                        
# ERLANG                                                                                                                                                                 
#                                                                                                                                                                        
                                                                                                                                                                         
ENV ERLANG_VERSION="1:23.2.3-1"                                                                                                                                          
                                                                                                                                                                         
RUN wget https://packages.erlang-solutions.com/erlang-solutions_1.0_all.deb && dpkg -i erlang-solutions_1.0_all.deb                                                      
                                                                                                                                                                         
RUN apt-get update && \                                                                                                                                                  
    apt-get install -yy --no-install-recommends esl-erlang=${ERLANG_VERSION}                                                                                             
                                                                                                                                                                         
#                                                                                                                                                                        
# ELIXIR                                                                                                                                                                 
#                                                                                                                                                                        
                                                                                                                                                                         
                                                                                                                                                                         
ENV ELIXIR_VERSION="v1.11.3"                                                                                                                                             
                                                                                                                                                                         
RUN set -xe \                                                                                                                                                            
  && ELIXIR_DOWNLOAD_URL="https://github.com/elixir-lang/elixir/releases/download/${ELIXIR_VERSION}/Precompiled.zip" \                                                   
  && buildDeps=' \                                                                                                                                                       
    unzip \                                                                                                                                                              
  ' \                                                                                                                                                                    
  && apt-get update \                                                                                                                                                    
  && apt-get install -y --no-install-recommends $buildDeps \                                                                                                             
  && curl -fSL -o elixir-precompiled.zip $ELIXIR_DOWNLOAD_URL \                                                                                                          
  && unzip -d /usr/local elixir-precompiled.zip \                                                                                                                        
  && rm elixir-precompiled.zip                                                                                                                                           
                                                                                                                                                                         
#                                                                                                                                                                        
# Hex  + Rebar                                                                                                                                                           
#                                                                                                                                                                        
                                                                                                                                                                         
ENV MIX_ENV=prod                                                                                                                                                         
                                                                                                                                                                         
RUN mix local.hex --force                                                                                                                                                
RUN mix local.rebar --force  

This last step times out when building the dockedr image. I can also reproduce the same issue by running docker run ... mix local.rebar --force. Every 5 or 6 runs this fails with timeout:

** (Mix) request timed out after 60000ms

Could not install Rebar because Mix could not download metadata at https://repo.hex.pm/installs/rebar3-1.x.csv.

or

** (Mix) request timed out after 60000ms
Could not fetch rebar at:
    https://repo.hex.pm/installs/1.0.0/rebar-2.6.2
Please download the file above manually to your current directory and run:
    mix local.rebar rebar ./rebar

When I run mix local.rebar --force on the host machine I have no such issue no matter how many times I run it.

There are obvious differences in the set up: my dev machine is Ubuntu 20.4, and Docker image is Debian stretch. Again, I can’t reproduce it on my dev machine’s host OS.

When the above sometimes succeeds in Docker image, then I get errors when installing deps:

$ mix deps.get
Failed to fetch record for 'hexpm/timex' from registry (using cache instead)00:16
** (Mix) Unknown package timex in lockfile

Again, from CI / Docker image only. Not from host machine, that works fine.

So… any ideas anyone what can cause the Docker image to have these connectivity issues? This is happening both on CI and on my dev machine when I run the image.