Add docker build files

Dockerfile

+ARG ALPINE_VERSION=3.8
+
+FROM elixir:1.7.2-alpine AS builder
+
+ARG APP_NAME
+ARG APP_VSN
+ARG MIX_ENV
+ARG PHOENIX_SUBDIR=.
+
+ENV APP_NAME=${APP_NAME} \
+    APP_VSN=${APP_VSN} \
+    MIX_ENV=${MIX_ENV}
+
+# By convention, /opt is typically used for applications
+WORKDIR /opt/gaja
+
+# This step installs all the build tools we'll need
+RUN apk update && \
+  apk upgrade --no-cache && \
+  apk add --no-cache \
+    git \
+    build-base && \
+  mix local.rebar --force && \
+  mix local.hex --force
+
+RUN git clone --single-branch --depth 1 https://gitlab.com/personal-server-community/personal-database.git /opt/gaja
+
+RUN mix do deps.get, deps.compile, compile
+
+RUN \
+  mkdir -p /opt/built && \
+  mix release --verbose && \
+  cp _build/${MIX_ENV}/rel/${APP_NAME}/releases/${APP_VSN}/${APP_NAME}.tar.gz /opt/built && \
+  cd /opt/built && \
+  tar -xzf ${APP_NAME}.tar.gz && \
+  rm ${APP_NAME}.tar.gz
+
+FROM alpine:${ALPINE_VERSION}
+
+ARG APP_NAME=gaja
+
+RUN apk update && \
+    apk add --no-cache \
+      bash \
+      openssl-dev
+
+ENV REPLACE_OS_VARS=true \
+    APP_NAME=${APP_NAME}
+
+WORKDIR /opt/gaja
+
+COPY --from=builder /opt/built .
+
+CMD trap 'exit' INT; /opt/gaja/bin/${APP_NAME} foreground

Makefile

+.PHONY: help
+
+APP_NAME ?= `grep 'app:' mix.exs | sed -e 's/\[//g' -e 's/ //g' -e 's/app://' -e 's/[:,]//g'`
+APP_VSN ?= `grep 'version:' mix.exs | cut -d '"' -f2`
+BUILD ?= `git rev-parse --short HEAD`
+
+help:
+	@echo "$(APP_NAME):$(APP_VSN)-$(BUILD)"
+	@perl -nle'print $& if m{^[a-zA-Z_-]+:.*?## .*$$}' $(MAKEFILE_LIST) | sort | awk 'BEGIN {FS = ":.*?## "}; {printf "\033[36m%-30s\033[0m %s\n", $$1, $$2}'
+
+build: ## Build the Docker image
+	docker build --build-arg APP_NAME=$(APP_NAME) \
+		--build-arg APP_VSN=$(APP_VSN) \
+		--build-arg MIX_ENV=prod \
+		-t $(APP_NAME):$(APP_VSN)-$(BUILD) \
+		-t $(APP_NAME):latest .
+
+run: ## Run the app in Docker
+	docker run --env-file config/docker.env \
+		--expose 4000 -p 4000:4000 \
+		--rm -it $(APP_NAME):latest

config/docker.env

+HOSTNAME=localhost
+SECRET_KEY_BASE="u1QXlca4XEZKb1o3HL/aUlznI1qstCNAQ6yme/lFbFIs0Iqiq/annZ+Ty8JyUCDc"
+DATABASE_HOST=db
+DATABASE_USER=postgres
+DATABASE_PASS=postgres
+DATABASE_NAME=myapp_db
+PORT=4000
+LANG=en_US.UTF-8
+REPLACE_OS_VARS=true
+ERLANG_COOKIE=gaja

config/prod.secret.exs

@@ -9,12 +9,13 @@ use Mix.Config
 # kept out of version control and might be hard to recover
 # or recreate for your teammates (or yourself later on).
 config :gaja, Gaja.Endpoint,
-  secret_key_base: "80uFIZUtGYfo69S+zieHRQHb1IJrFFyXlq5jzjHsh3ypk3Q1PCNZNrmTVg83eYhZ"
+  secret_key_base: System.get_env("SECRET_KEY_BASE")
 
 # Configure your database
 config :gaja, Gaja.Repo,
   adapter: Ecto.Adapters.Postgres,
-  username: "postgres",
-  password: "postgres",
-  database: "gaja_prod",
+  username: System.get_env("DATABASE_USER"),
+  password: System.get_env("DATABASE_PASS"),
+  database: System.get_env("DATABASE_NAME"),
+  hostname: System.get_env("DATABASE_HOST"),
   pool_size: 15