Graduate python3-debian from incubator

**What**
- Copy the python3-debian template from https://github.com/openfaas-incubator/python3-debian
- Update the dockerfile to be non-root, this adapts the same
  modifications/commands that the alpine dockerfile uses, but ofcourse
  adapted to debian

Resolves openfaas-incubator/python3-debian#10
Resolves openfaas-incubator/python3-debian#7

Signed-off-by: Lucas Roesler <[email protected]>

template/python3-debian/Dockerfile

@@ -0,0 +1,53 @@
+FROM openfaas/classic-watchdog:0.18.1 as watchdog
+FROM python:3
+
+# Allows you to add additional packages via build-arg
+ARG ADDITIONAL_PACKAGE
+
+COPY --from=watchdog /fwatchdog /usr/bin/fwatchdog
+RUN chmod +x /usr/bin/fwatchdog
+RUN apt-get update \
+    && apt-get install -y ca-certificates ${ADDITIONAL_PACKAGE} \
+    && rm -rf /var/lib/apt/lists/
+
+# Add non root user
+RUN groupadd app && useradd -r -g app app
+
+WORKDIR /home/app/
+
+COPY index.py           .
+COPY requirements.txt   .
+
+RUN chown -R app /home/app && \
+    mkdir -p /home/app/python && chown -R app /home/app
+USER app
+ENV PATH=$PATH:/home/app/.local/bin:/home/app/python/bin/
+ENV PYTHONPATH=$PYTHONPATH:/home/app/python
+
+RUN pip install -r requirements.txt --target=/home/app/python
+
+RUN mkdir -p function
+RUN touch ./function/__init__.py
+
+WORKDIR /home/app/function/
+COPY function/requirements.txt	.
+
+RUN pip install -r requirements.txt --target=/home/app/python
+
+WORKDIR /home/app/
+
+USER root
+
+COPY function           function
+
+RUN chown -R app:app ./ && \
+    chmod -R 777 /home/app/python
+
+USER app
+
+ENV fprocess="python3 index.py"
+EXPOSE 8080
+
+HEALTHCHECK --interval=3s CMD [ -e /tmp/.lock ] || exit 1
+
+CMD ["fwatchdog"]

template/python3-debian/function/handler.py

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+def handle(req):
+    """handle a request to the function
+    Args:
+        req (str): request body
+    """
+
+    return req

template/python3-debian/index.py

@@ -0,0 +1,20 @@
+# Copyright (c) Alex Ellis 2017. All rights reserved.
+# Licensed under the MIT license. See LICENSE file in the project root for full license information.
+
+import sys
+from function import handler
+
+def get_stdin():
+    buf = ""
+    while(True):
+        line = sys.stdin.readline()
+        buf += line
+        if line=="":
+            break
+    return buf
+
+if(__name__ == "__main__"):
+    st = get_stdin()
+    ret = handler.handle(st)
+    if ret != None:
+        print(ret)

template/python3-debian/template.yml

@@ -0,0 +1,2 @@
+language: python3-debian
+fprocess: python3 index.py