Standarize image by using shared / similair layers

services/fetchmail/Dockerfile

@@ -1,7 +1,11 @@
-FROM python:3-alpine
-
+FROM alpine:3.8
+# python3 shared with most images
+RUN apk add --no-cache \
+    python3 py3-pip \
+  && pip3 install --upgrade pip
+# Image specific layers under this line
 RUN apk add --no-cache fetchmail ca-certificates \
- && pip install requests
+ && pip3 install requests
 
 COPY fetchmail.py /fetchmail.py
 USER fetchmail

services/fetchmail/fetchmail.py

@@ -1,4 +1,4 @@
-#!/usr/bin/env python
+#!/usr/bin/python3
 
 import time
 import os

services/rspamd/Dockerfile

@@ -1,8 +1,14 @@
 FROM alpine:3.8
-
-RUN apk add --no-cache python py-jinja2 rspamd rspamd-controller rspamd-proxy rspamd-fuzzy ca-certificates py-pip curl\
- && pip install --upgrade pip \
- && pip install tenacity
+# python3 shared with most images
+RUN apk add --no-cache \
+    python3 py3-pip \
+  && pip3 install --upgrade pip
+# Shared layer between rspamd, postfix, dovecot, unbound and nginx
+RUN pip3 install jinja2
+# Shared layer between rspamd, postfix, dovecot
+RUN pip3 install tenacity
+# Image specific layers under this line
+RUN apk add --no-cache rspamd rspamd-controller rspamd-proxy rspamd-fuzzy ca-certificates curl
 
 RUN mkdir /run/rspamd
 

services/rspamd/start.py

@@ -1,4 +1,4 @@
-#!/usr/bin/python
+#!/usr/bin/python3
 
 import jinja2
 import os

services/unbound/Dockerfile

@@ -1,7 +1,12 @@
-FROM python:3-alpine
-
+FROM alpine:3.8
+# python3 shared with most images
+RUN apk add --no-cache \
+    python3 py3-pip \
+  && pip3 install --upgrade pip
+# Shared layer between rspamd, postfix, dovecot, unbound and nginx
+RUN pip3 install jinja2
+# Image specific layers under this line
 RUN apk add --no-cache unbound curl bind-tools \
-  && pip3 install jinja2 \
   && curl -o /etc/unbound/root.hints https://www.internic.net/domain/named.cache \
   && chown root:unbound /etc/unbound \
   && chmod 775 /etc/unbound \

services/unbound/start.py

@@ -1,4 +1,4 @@
-#!/usr/local/bin/python3
+#!/usr/bin/python3
 
 import jinja2
 import os