Adds dockerfile

Dockerfile

@@ -0,0 +1,67 @@
+# Use an official Elixir runtime as a parent image
+FROM elixir:1.12-slim AS build
+
+# Set the environment to production
+ENV MIX_ENV=prod
+
+# Install system dependencies
+RUN apt-get update && \
+    apt-get install -y build-essential sqlite3 libsqlite3-dev && \
+    apt-get clean
+
+# Install hex and rebar
+RUN mix local.hex --force && \
+    mix local.rebar --force
+
+# Create the application build directory
+WORKDIR /app
+
+# Copy our mix files and fetch our dependencies
+COPY mix.exs mix.lock ./
+COPY config config
+RUN mix do deps.get, deps.compile
+
+# Set Node.js environment to production
+ENV NODE_ENV=production
+
+# Use Node.js to install assets
+FROM node:14 AS node-build
+WORKDIR /app/assets
+COPY assets/package.json assets/package-lock.json ./
+RUN npm install
+COPY assets/ ./
+RUN npm run deploy
+
+# Switch back to our Elixir image to continue building
+FROM build AS app-build
+WORKDIR /app
+COPY --from=node-build /app/assets/build ./priv/static
+RUN mix phx.digest
+
+# Copy our application source code
+COPY lib lib
+COPY priv priv
+
+# Compile and build the application
+RUN mix do compile, phx.digest
+
+# Create the release
+RUN mix release
+
+# ---- Application Stage ----
+FROM debian:buster-slim AS app
+
+# Install runtime dependencies
+RUN apt-get update && apt-get install -y openssl libsqlite3-0 && apt-get clean
+
+# Create and switch to the app user
+RUN useradd --create-home app
+USER app
+WORKDIR /home/app
+
+# Copy over the build artifact from the previous step and create a symlink
+COPY --from=build --chown=app:app /app/_build/prod/rel/my_app ./
+RUN ln -s /home/app/my_app/bin/my_app /home/app/bin
+
+# Specify the entry point
+ENTRYPOINT ["bin/my_app", "start"]