Create docker.exs and docker-entrypoint + round out Dockerfile

At this point, the implementation is completely working and has been
tested running live and federating with other instances.

Dockerfile

@@ -2,7 +2,7 @@ FROM rinpatch/elixir:1.9.0-rc.0-alpine as build
 
 COPY . .
 
-ENV MIX_ENV prod
+ENV MIX_ENV=prod
 
 RUN apk add git gcc g++ musl-dev make &&\
 	echo "import Mix.Config" > config/prod.secret.exs &&\
@@ -15,18 +15,27 @@ RUN mix deps.get --only prod &&\
 
 FROM alpine:latest
 
+ARG HOME=/opt/pleroma
+ARG DATA=/var/lib/pleroma
+
 RUN echo "http://nl.alpinelinux.org/alpine/latest-stable/community" >> /etc/apk/repositories &&\
 	apk update &&\
 	apk add ncurses postgresql-client
 
-RUN adduser --system --shell /bin/false --home /opt/pleroma pleroma &&\
-	mkdir -p /var/lib/pleroma/uploads &&\
-	chown -R pleroma /var/lib/pleroma &&\
-	mkdir -p /var/lib/pleroma/static &&\
-	chown -R pleroma /var/lib/pleroma &&\
+RUN adduser --system --shell /bin/false --home ${HOME} pleroma &&\
+	mkdir -p ${DATA}/uploads &&\
+	mkdir -p ${DATA}/static &&\
+	chown -R pleroma ${DATA} &&\
 	mkdir -p /etc/pleroma &&\
 	chown -R pleroma /etc/pleroma
 
 USER pleroma
 
-COPY --from=build --chown=pleroma:0 /release/ /opt/pleroma/
+COPY --from=build --chown=pleroma:0 /release ${HOME}
+
+COPY ./config/docker.exs /etc/pleroma/config.exs
+COPY ./docker-entrypoint.sh ${HOME}
+
+EXPOSE 4000
+
+ENTRYPOINT ["/opt/pleroma/docker-entrypoint.sh"]

config/docker.exs

+import Config
+
+config :pleroma, Pleroma.Web.Endpoint,
+   url: [host: System.get_env("DOMAIN", "localhost"), scheme: "https", port: 443],
+   http: [ip: {0, 0, 0, 0}, port: 4000]
+
+config :pleroma, :instance,
+  name: System.get_env("INSTANCE_NAME", "Pleroma"),
+  email: System.get_env("ADMIN_EMAIL"),
+  notify_email: System.get_env("NOTIFY_EMAIL"),
+  limit: 5000,
+  registrations_open: false,
+  dynamic_configuration: true
+
+config :pleroma, Pleroma.Repo,
+  adapter: Ecto.Adapters.Postgres,
+  username: System.get_env("DB_USER", "pleroma"),
+  password: System.fetch_env!("DB_PASS"),
+  database: System.get_env("DB_NAME", "pleroma"),
+  hostname: System.get_env("DB_HOST", "db"),
+  pool_size: 10
+
+# Configure web push notifications
+config :web_push_encryption, :vapid_details,
+  subject: "mailto:#{System.get_env("NOTIFY_EMAIL")}"
+
+config :pleroma, :database, rum_enabled: false
+config :pleroma, :instance, static_dir: "/var/lib/pleroma/static"
+config :pleroma, Pleroma.Uploaders.Local, uploads: "/var/lib/pleroma/uploads"
+
+# We can't store the secrets in this file, since this is baked into the docker image
+if not File.exists?("/var/lib/pleroma/secret.exs") do
+  secret = :crypto.strong_rand_bytes(64) |> Base.encode64() |> binary_part(0, 64)
+  signing_salt = :crypto.strong_rand_bytes(8) |> Base.encode64() |> binary_part(0, 8)
+  {web_push_public_key, web_push_private_key} = :crypto.generate_key(:ecdh, :prime256v1)
+
+  secret_file = EEx.eval_string(
+    """
+    import Config
+    
+    config :pleroma, Pleroma.Web.Endpoint,
+      secret_key_base: "<%= secret %>",
+      signing_salt: "<%= signing_salt %>"
+    
+    config :web_push_encryption, :vapid_details,
+      public_key: "<%= web_push_public_key %>",
+      private_key: "<%= web_push_private_key %>"
+    """,
+    secret: secret,
+    signing_salt: signing_salt,
+    web_push_public_key: Base.url_encode64(web_push_public_key, padding: false),
+    web_push_private_key: Base.url_encode64(web_push_private_key, padding: false)
+  )
+
+  File.write("/var/lib/pleroma/secret.exs", secret_file)
+end
+
+import_config("/var/lib/pleroma/secret.exs")
+
+# For additional user config
+if File.exists?("/var/lib/pleroma/config.exs"),
+  do: import_config("/var/lib/pleroma/config.exs"),
+  else: File.write("/var/lib/pleroma/config.exs", """
+  import Config
+  
+  # For additional configuration outside of environmental variables
+  """)

docker-entrypoint.sh

+#!/bin/ash
+
+set -e
+
+echo "-- Waiting for database..."
+while ! pg_isready -U ${DB_USER:-pleroma} -d postgres://${DB_HOST:-db}:5432/${DB_NAME:-pleroma} -t 1; do
+    sleep 1s
+done
+
+echo "-- Running migrations..."
+$HOME/bin/pleroma_ctl migrate
+
+echo "-- Starting!"
+exec $HOME/bin/pleroma start