Update Dockerfile

Dockerfile

@@ -1,20 +1,13 @@
-FROM ubuntu:latest
+FROM alpine
 
 # Labels
-LABEL maintainer="Paulino Padial <github.com/ppadial>"
+LABEL maintainer="Charles Lu <github.com/charleszlu>"
 
 # Environment variables (with default values)
 ENV CRON_LOG_LEVEL=8
 
-# PostgreSQL 10 repository install
-RUN apt-get update && apt-get upgrade -y && \
-    apt-get install -y wget lsb-release && \
-    wget -q https://www.postgresql.org/media/keys/ACCC4CF8.asc -O - | apt-key add - && \
-    echo "deb http://apt.postgresql.org/pub/repos/apt/ `lsb_release -cs`-pgdg main" >> /etc/apt/sources.list.d/pgdg.list
-
 # Packages installation
-RUN apt-get update && apt-get upgrade -y && \
-    apt-get install -y autopostgresqlbackup cron bzip2 gzip postgresql-client && \
+RUN apk --update add --no-cache bash cron bzip2 gzip postgresql-client && \
     apt-get purge -y --auto-remove && \
     rm -rf /var/lib/apt/lists/*