docker: Move container to buster-slim

Move builder and runner stages to buster-slim to get newer versions
of go, deboostrap and libostree.

Signed-off-by: Frédéric Danis <frederic.danis@collabora.com>

docker/Dockerfile

@@ -1,56 +1,57 @@
+# Global ARGs shared by all stages
+ARG DEBIAN_FRONTEND=noninteractive
+ARG GOPATH=/usr/local/go
+
 ### first stage - builder ###
-FROM golang:1.10 as builder
+FROM debian:buster-slim as builder
 
-MAINTAINER Maciej Pijanowski <maciej.pijanowski@3mdeb.com>
-
-ENV HOME=/scratch
+ARG DEBIAN_FRONTEND
+ARG GOPATH
 
 # install debos build dependencies
 RUN apt-get update && \
     apt-get install -y --no-install-recommends \
-    libglib2.0-dev \
-    libostree-dev \
-    && rm -rf /var/lib/apt/lists/*
+        ca-certificates \
+        golang-go \
+        gcc \
+        git \
+        libostree-dev \
+        libc6-dev && \
+    rm -rf /var/lib/apt/lists/*
 
+# Build debos
 RUN go get -d github.com/go-debos/debos/cmd/debos
-WORKDIR /go/src/github.com/go-debos/debos/
+WORKDIR $GOPATH/src/github.com/go-debos/debos/
 RUN GOOS=linux go build -a cmd/debos/debos.go
 
 ### second stage - runner ###
-FROM debian:stretch-slim as runner
+FROM debian:buster-slim as runner
 
-ARG DEBIAN_FRONTEND=noninteractive
+ARG DEBIAN_FRONTEND
+ARG GOPATH
 
 # debos runtime dependencies
 # ca-certificates is required to validate HTTPS certificates when getting debootstrap release file
 RUN apt-get update && \
     apt-get install -y --no-install-recommends \
-    libostree-1-1 \
-    ca-certificates \
-    systemd-container \
-    binfmt-support \
-    parted \
-    dosfstools \
-    e2fsprogs \
-    bmap-tools \
-    # fakemachine runtime dependencies
-    qemu-system-x86 \
-    qemu-user-static \
-    busybox \
-    linux-image-amd64 \
-    systemd \
-    dbus \
-    && rm -rf /var/lib/apt/lists/*
-
-# Bug description: https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=806780
-# It was fixed in debootstrap 1.0.96 while Stretch provides 1.0.89. Backports
-# provide 1.0.100.
-RUN printf "deb http://httpredir.debian.org/debian stretch-backports main \ndeb-src http://httpredir.debian.org/debian stretch-backports main" > /etc/apt/sources.list.d/backports.list && \
-    apt-get update && \
-    apt-get -t stretch-backports install -y --no-install-recommends \
-    debootstrap && \
+        libostree-1-1 \
+        ca-certificates \
+        debootstrap \
+        systemd-container \
+        binfmt-support \
+        parted \
+        dosfstools \
+        e2fsprogs \
+        bmap-tools \
+        # fakemachine runtime dependencies
+        qemu-system-x86 \
+        qemu-user-static \
+        busybox \
+        linux-image-amd64 \
+        systemd \
+        dbus && \
     rm -rf /var/lib/apt/lists/*
 
-COPY --from=builder /go/src/github.com/go-debos/debos/debos /usr/bin/debos
+COPY --from=builder $GOPATH/src/github.com/go-debos/debos/debos /usr/bin/debos
 
 WORKDIR /root