Use SLIM version of Python as docker base image

Dockerfile

@@ -1,36 +1,26 @@
-FROM alpine:latest
+FROM python:3-slim
 
 # Set working space
 WORKDIR /usr/src/app
 
 # Install dependencies
-RUN apk update \
-    # Install packages
-    && apk add \
-        tzdata \
-        build-base freetype-dev libpng-dev openblas-dev \
-        python3 py3-pip py3-numpy py3-pandas py3-matplotlib \
-        wkhtmltopdf \
+RUN apt-get update \
+    # Prevent endless waiting
+    && DEBIAN_FRONTEND=noninteractive \
     # Set UTC as timezone
     && ln -snf /usr/share/zoneinfo/Europe/Rome /etc/localtime \
+    # Install APT packages
+    && apt-get install -y --fix-missing wkhtmltopdf \
     # Remove tmp files
-    && rm -rf /tmp/* /var/tmp/* \
+    && apt-get clean && rm -rf /tmp/* /var/tmp/* \
     # Add PiWheels support
     && echo "[global]\nextra-index-url=https://www.piwheels.org/simple" >> /etc/pip.conf \
     # Upgrade PIP 
     && python3 -m pip install --no-cache-dir --upgrade pip
 
-# Copy requirements
+# Copy and install requirements
 COPY requirements.txt .
-
-# Install requirements
-RUN apk update \
-    # Install tmp packages 
-    && apk add --virtual build-deps gcc python3-dev musl-dev \
-    # Install PIP packages
-    && python3 -m pip install --no-cache-dir -r requirements.txt \
-    # Delete tmp packages
-    && apk del build-deps
+RUN python3 -m pip install -r requirements.txt
 
 # Copy app
 COPY . .