Dockerfile

#
# Step 1 - build the OTP binary
#
FROM elixir:1.9-alpine AS builder

ARG APP_NAME
ARG APP_VERSION
ARG MIX_ENV=prod

ENV APP_NAME=${APP_NAME} \
    APP_VERSION=${APP_VERSION} \
    MIX_ENV=${MIX_ENV}

WORKDIR /build

# This step installs all the build tools we'll need
RUN apk update && \
    apk upgrade --no-cache && \
    apk add --no-cache nodejs~=10.14 npm~=10.14 git build-base
RUN mix local.rebar --force && \
    mix local.hex --force

# This copies our app source code into the build container
COPY mix.* ./
RUN mix deps.get --only ${MIX_ENV}

COPY . .
RUN mix compile

RUN npm ci --prefix assets --no-audit --no-color --unsafe-perm

# Compile assets and generate digest filenames
RUN npm run --prefix assets deploy
RUN mix phx.digest

RUN mkdir -p /opt/build && \
    mix release && \
    cp -R _build/${MIX_ENV}/rel/${APP_NAME}/* /opt/build

#
# Step 2 - build a lean runtime container
#
FROM alpine:3.9

ARG APP_NAME
ENV APP_NAME=${APP_NAME}

# Update kernel and install runtime dependencies
RUN apk --no-cache update && \
    apk --no-cache upgrade && \
    apk --no-cache add bash openssl-dev erlang-crypto

WORKDIR /opt/elixir_boilerplate

# Copy the OTP binary from the build step
COPY --from=builder /opt/build .

# Copy the entrypoint script
COPY priv/scripts/docker-entrypoint.sh /usr/local/bin
RUN chmod a+x /usr/local/bin/docker-entrypoint.sh

# Create a non-root user
RUN adduser -D elixir_boilerplate && \
    chown -R elixir_boilerplate: /opt/elixir_boilerplate

USER elixir_boilerplate

ENTRYPOINT ["docker-entrypoint.sh"]
CMD ["start"]