using stretch slim package for less space and bandwidth requirements (#…

…157)

Signed-off-by: Tully Foote <[email protected]>

src/rocker/os_detector.py

@@ -21,16 +21,18 @@
 
 
 DETECTION_TEMPLATE="""
-FROM python:3-stretch as detector
+FROM python:3-slim-stretch as detector
 # Force the older version of debian for detector.
 # GLIBC is forwards compatible but not necessarily backwards compatible for pyinstaller
 # https://github.com/pyinstaller/pyinstaller/wiki/FAQ#gnulinux
 # StaticX is supposed to take care of this but there appears to be an issue when using subprocess
 
 RUN mkdir -p /tmp/distrovenv
 RUN python3 -m venv /tmp/distrovenv
+# patchelf needed for staticx
+# binutils provides objdump needed by pyinstaller
+RUN apt-get update && apt-get install -qy patchelf binutils
 RUN . /tmp/distrovenv/bin/activate && pip install distro pyinstaller==4.0 staticx
-RUN apt-get update && apt-get install -qy patchelf #needed for staticx
 
 RUN echo 'import distro; import sys; output = (distro.name(), distro.version(), distro.codename()); print(output) if distro.name() else sys.exit(1)' > /tmp/distrovenv/detect_os.py
 RUN . /tmp/distrovenv/bin/activate && pyinstaller --onefile /tmp/distrovenv/detect_os.py