Dockerfile: fix certificate warning
Install the certificates before switching
to a local mirror.
@@ -6,9 +6,11 @@ ENV DEBIAN_FRONTEND noninteractive
USER root
# Tools
-RUN sed -i -e 's#http://archive.ubuntu.com/ubuntu/#mirror://mirrors.ubuntu.com/mirrors.txt#' /etc/apt/sources.list && \
+RUN apt-get -qq update && \
+ apt-get -qq -y --no-install-recommends install ca-certificates > /dev/null && \
+ sed -i -e 's#http://archive.ubuntu.com/ubuntu/#mirror://mirrors.ubuntu.com/mirrors.txt#' /etc/apt/sources.list && \
apt-get -qq update && \
- apt-get -qq -y --no-install-recommends install gnupg ca-certificates software-properties-common > /dev/null
+ apt-get -qq -y --no-install-recommends install gnupg software-properties-common > /dev/null
RUN apt-key adv --keyserver hkp://keyserver.ubuntu.com:80 --recv-keys 3FA7E0328081BFF6A14DA29AA6A19B38D3D831EF && \
echo "deb http://download.mono-project.com/repo/ubuntu stable-bionic main" | tee /etc/apt/sources.list.d/mono-xamarin.list && \
