Cannot find when launching elixir app


I am using elixir 1.9 with erlang 22.0 and I am using the command mix release. However when I try to run my app with _build/dev/rel/andy/bin/my_app start start I get an error:


This is the error I get when trying to run it:

/home/devops/_build/dev/rel/my_app/erts-10.4.3/bin/beam.smp: error while loading shared libraries: cannot open shared object file: No such file or directory

To fix it I tried running sudo apt-get install but it doesn’t look like it exists:

Reading package lists... Done
Building dependency tree       
Reading state information... Done
E: Unable to locate package
E: Couldn't find any package by glob ''
E: Couldn't find any package by regex ''

This is my OS operation:

No LSB modules are available.
Distributor ID:	Ubuntu
Description:	Ubuntu 16.04.6 LTS
Release:	16.04
Codename:	xenial

How can I fix this?

You probably build your release on a different setup, one which had available.

Please build the release on an Ubuntu 16.04.6 and nothing else.


$ curl "" | zgrep libtinfo
libtinfo-dev (6.0+20160213-1ubuntu1) developer's library for the low-level terminfo library
libtinfo5 (6.0+20160213-1ubuntu1) shared low-level terminfo library for terminal handling
libtinfo5-dbg (6.0+20160213-1ubuntu1) debugging/profiling library for the low-level terminfo library

For 16.04 only libtinfo5 is available as it seems.

It contains the following files (

  • /lib/x86_64-linux-gnu/
  • /lib/x86_64-linux-gnu/
  • /usr/lib/x86_64-linux-gnu/
  • /usr/lib/x86_64-linux-gnu/
  • /usr/share/doc/libtinfo5/TODO.Debian
  • /usr/share/doc/libtinfo5/changelog.Debian.gz
  • /usr/share/doc/libtinfo5/copyright

I have the same error when trying to run an app that I built in Docker on the Elixir 1.9.1 image, my Dockerfile is:

FROM elixir:1.9.1 AS builder
WORKDIR /app/monolith
COPY . .
WORKDIR /app/monolith/apps/server
RUN mix local.hex --force; mix local.rebar --force
RUN mix deps.get
RUN mix compile 

FROM builder AS release 
WORKDIR /app/monolith/apps/server
RUN mix release 
ENTRYPOINT ["/app/monolith/_build/prod/rel/server/bin/server"]

Do you see that error when you start or when you build that docker, or are you extracting the built release and run it elsewhere?

I believe this error was due to my copying build/release artifacts into my image. I added _build to .dockerignore and now the app starts.

To answer your question, the crash occurred whether running in the same container as the build or copying the release to a fresh one.

Yeah, _build and deps from your host should never slip into the container, or vice versa…

Also there are some other culprits with your dockerfile. Even the final stage still contains all the temporary artifacts and source code. This increases the size of the resulting image unnecessarily. You should try to properly use the multi-stage you already started with.

Yup, thank you. I got it working with the following Dockerfile:

FROM elixir:1.9.1 AS builder
WORKDIR /app/monolith
COPY . .
WORKDIR /app/ 
WORKDIR /app/monolith/apps/server
RUN mix local.hex --force; mix local.rebar --force
RUN mix deps.get
RUN mix compile 

FROM builder AS release 
WORKDIR /app/monolith/apps/server
RUN mix release 
ENTRYPOINT ["/app/monolith/_build/dev/rel/server/bin/server"]

FROM base AS runner
COPY --from=release /app/monolith/_build/dev/rel/server/ /app
ENTRYPOINT [ "/app/bin/server" ]

and .dockerignore:


Still needs a bit of work, in particular to allow prod builds, but its a start.

(I take your point about not copying in the deps, but that is giving me issues with a timeout from when fetching tzdata.)

Please also add deps to your .dockerignoe. Some packages create artifacts in there :frowning:

Also, I can’t see where you define base, but you reference it. Just from looking at it, this wont actually work.

Thanks. I will add deps, good to know how important that is.

The base image is stored in my internal repository, and is just Ubuntu with a couple of basic changes.

Just as addition here: I got this error because the build was running on Ubuntu 18.10 but my prod is running on Ubuntu 18.04. So I migrated my pipeline back to 18.04 and everything is fine again

Just for the record, I came across this yesterday, same issue, etc. and this is the final working Dockerfile I came up with, in case anybody finds it useful.

FROM elixir:1.10.3 AS app_builder

ENV MIX_ENV=prod \

# Build local package repository
RUN mix local.hex --force && \
    mix local.rebar --force

RUN mkdir /app

# Compile dependencies
COPY mix.exs .
COPY mix.lock .
RUN mix deps.get && mix deps.compile

# Let's make sure we have node
RUN curl -sL | bash - && \
    apt-get install -y nodejs

# Compile assets
COPY assets ./assets
RUN npm install --prefix ./assets && \
    npm run deploy --prefix ./assets

# Now, let's go with the actual elixir code. The order matters: if we only
# change elixir code, all the above layers will be cached ~ less image build time.
COPY config ./config
COPY lib ./lib
COPY priv ./priv

# Final build step: digest static assets and generate the release
RUN mix phx.digest && mix release

FROM debian:buster-slim AS app


RUN apt-get update && apt-get install -y openssl

RUN useradd --create-home app
WORKDIR /home/app
COPY --from=app_builder /app/_build .
RUN chown -R app: ./prod
USER app

CMD ["./prod/rel/cookbook/bin/cookbook", "start"]