Revise apk package handling

rootfs/expandybird/Dockerfile

@@ -17,22 +17,11 @@ FROM alpine:3.3
 COPY . /
 
 # install common packages
-RUN apk add --update-cache curl python
-
-WORKDIR /opt
-
-# install pip
-RUN curl -sSL https://raw.githubusercontent.com/pypa/pip/7.1.2/contrib/get-pip.py | python -
+RUN apk add --no-cache curl python py-pip
 
 # install dependencies
 RUN pip install --disable-pip-version-check --no-cache-dir -r /opt/expansion/requirements.txt
 
-# cleanup.
-RUN apk del --purge \
-  curl \
-  python \
-  && rm -rf /var/cache/apk/*
-
 # define execution environment
 CMD ["/bin/expandybird", "-expansion_binary", "/opt/expansion/expansion.py"]
 EXPOSE 8000

rootfs/manager/Dockerfile

@@ -16,9 +16,7 @@ FROM alpine:3.3
 COPY . /
 
 # Install CA certs
-RUN apk add --update-cache ca-certificates
-RUN apk del --purge ca-certificates \
-  && rm -rf /var/cache/apk/*
+RUN apk add --no-cache ca-certificates
 
 EXPOSE 8080
 CMD ["/bin/manager", "--kubectl=/bin/kubectl"]

rootfs/resourcifier/Dockerfile

@@ -16,9 +16,7 @@ FROM alpine:3.3
 COPY . /
 
 # Install CA certs
-RUN apk add --update-cache ca-certificates
-RUN apk del --purge ca-certificates \
-  && rm -rf /var/cache/apk/*
+RUN apk add --no-cache ca-certificates
 
 EXPOSE 8080
 CMD ["/bin/resourcifier", "--kubectl=/bin/kubectl"]