Dockerfile

# The version of Alpine to use for the final image
ARG ALPINE_VERSION=3.9

FROM elixir:1.8.1-alpine AS builder

# The following are build arguments used to change variable parts of the image.
# The name of your application/release (required)
ARG APP_NAME
# The version of the application we are building (required)
ARG APP_VSN
# The environment to build with
ARG MIX_ENV=prod
# Set this to true if this release is not a Phoenix app
ARG SKIP_PHOENIX=false
# If you are using an umbrella project, you can change this
# argument to the directory the Phoenix app is in so that the assets
# can be built
ARG PHOENIX_SUBDIR=apps/tweeter

ENV SKIP_PHOENIX=${SKIP_PHOENIX} \
    APP_NAME=${APP_NAME} \
    APP_VSN=${APP_VSN} \
    MIX_ENV=${MIX_ENV}

# By convention, /opt is typically used for applications
WORKDIR /opt/app

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

# This copies our app source code into the build container
COPY . .

RUN mix do deps.get, deps.compile, compile

# This step builds assets for the Phoenix app (if there is one)
# If you aren't building a Phoenix app, pass `--build-arg SKIP_PHOENIX=true`
# This is mostly here for demonstration purposes
RUN if [ ! "$SKIP_PHOENIX" = "true" ]; then \
    cd ${PHOENIX_SUBDIR}/assets && \
    yarn install && \
    yarn deploy && \
    cd .. && \
    mix phx.digest; \
    fi

RUN \
    mkdir -p /opt/built && \
    mix release --verbose && \
    cp _build/${MIX_ENV}/rel/${APP_NAME}/releases/${APP_VSN}/${APP_NAME}.tar.gz /opt/built && \
    cd /opt/built && \
    tar -xzf ${APP_NAME}.tar.gz && \
    rm ${APP_NAME}.tar.gz

# From this line onwards, we're in a new image, which will be the image used in production
FROM alpine:${ALPINE_VERSION}

# The name of your application/release (required)
ARG APP_NAME

# The time zone (needed by Timex)
ARG TZ=Asia/Manila

EXPOSE 4000

RUN apk update && \
    apk add --no-cache \
    bash \
    openssl-dev

ENV REPLACE_OS_VARS=true \
    TZ=${TZ} \
    APP_NAME=${APP_NAME} \
    HOSTNAME=localhost \
    PORT=4000

WORKDIR /opt/app

COPY --from=builder /opt/built .

CMD trap 'exit' INT; /opt/app/bin/${APP_NAME} foreground