Use base Debian image in Docker build

deployment/debian-package-x64/Dockerfile

@@ -1,18 +1,31 @@
-FROM microsoft/dotnet:2.2-sdk-buster
+FROM debian:10
 # Docker build arguments
 ARG SOURCE_DIR=/jellyfin
 ARG PLATFORM_DIR=/jellyfin/deployment/debian-package-x64
 ARG ARTIFACT_DIR=/dist
+ARG SDK_VERSION=2.2
 # Docker run environment
 ENV SOURCE_DIR=/jellyfin
 ENV ARTIFACT_DIR=/dist
 ENV DEB_BUILD_OPTIONS=noddebs
+ENV ARCH=amd64
 
 # Prepare Debian build environment
 RUN apt-get update \
- && apt-get install -y apt-transport-https debhelper gnupg wget devscripts mmv libc6-dev libcurl4-openssl-dev libfontconfig1-dev libfreetype6-dev \
- && ln -sf ${PLATFORM_DIR}/docker-build.sh /docker-build.sh \
- && mkdir -p ${SOURCE_DIR} && ln -sf ${PLATFORM_DIR}/pkg-src ${SOURCE_DIR}/debian
+ && apt-get install -y apt-transport-https debhelper gnupg wget devscripts mmv libc6-dev libcurl4-openssl-dev libfontconfig1-dev libfreetype6-dev
+
+# Install dotnet repository
+# https://dotnet.microsoft.com/download/linux-package-manager/debian9/sdk-current
+RUN wget https://download.visualstudio.microsoft.com/download/pr/69937b49-a877-4ced-81e6-286620b390ab/8ab938cf6f5e83b2221630354160ef21/dotnet-sdk-2.2.104-linux-x64.tar.gz -O dotnet-sdk.tar.gz \
+ && mkdir -p dotnet-sdk \
+ && tar -xzf dotnet-sdk.tar.gz -C dotnet-sdk \
+ && ln -s $( pwd )/dotnet-sdk/dotnet /usr/bin/dotnet
+
+# Link to docker-build script
+RUN ln -sf ${PLATFORM_DIR}/docker-build.sh /docker-build.sh
+
+# Link to Debian source dir; mkdir needed or it fails, can't force dest
+RUN mkdir -p ${SOURCE_DIR} && ln -sf ${PLATFORM_DIR}/pkg-src ${SOURCE_DIR}/debian
 
 VOLUME ${ARTIFACT_DIR}/