minor change

Dockerfile

@@ -5,7 +5,7 @@ MAINTAINER Andrey Arapov <andrey.arapov@nixaid.com>
 ENV DEBIAN_FRONTEND noninteractive
 
 RUN apt-get update && \
-    apt-get -y install sudo kmod attr \
+    apt-get -y --no-install-recommends install ca-certificates sudo kmod attr \
                        pulseaudio libcanberra-gtk-module libexif12 \
                        fonts-dejavu-core fonts-freefont-ttf fonts-guru-extra \
                        fonts-kacst fonts-kacst-one fonts-khmeros-core fonts-lao \
@@ -31,7 +31,7 @@ ADD https://dl.google.com/linux/direct/google-talkplugin_current_amd64.deb /tmp/
 
 RUN sh -c 'dpkg -i /tmp/google-talkplugin_current_amd64.deb 2>/dev/null; exit 0' && \
     apt-get update && \
-    apt-get -fy install && \
+    apt-get -fy --no-install-recommends install && \
     rm -rf -- /var/lib/apt/lists /tmp/*.deb
 
 # Workaround: pulseaudio client library likes to remove /dev/shm/pulse-shm-*