Dockerfile: drop use of Asylo base image
Use the base image and packages from the Asylo toolchain image:
-FROM gcr.io/asylo-framework/asylo:buildenv-v0.5.2
+# Use fixed snapshot of Debian to create a deterministic environment.
+# Snapshot tags can be found at https://hub.docker.com/r/debian/snapshot/tags
+ARG debian_snapshot=buster-20191118
+FROM debian/snapshot:${debian_snapshot}
+
+# Use a fixed version of Bazel.
+ARG bazel_version=1.2.1
+ARG bazel_sha=4bbb2718d451db5922223fda3aed3810c4ca50f431481e86a7fec4c585f18b1f
+ARG bazel_url=https://storage.googleapis.com/bazel-apt/pool/jdk1.8/b/bazel/bazel_${bazel_version}_amd64.deb
+
+RUN apt-get --yes update && \
+ apt-get install --yes wget && \
+ wget "${bazel_url}" -nv -o- -O bazel.deb && \
+ echo "${bazel_sha} bazel.deb" > bazel.sha256 && \
+ sha256sum --check bazel.sha256 && \
+ apt-get install -y \
+ ./bazel.deb \
+ bash-completion \
+ build-essential \
+ default-jdk-headless \
+ git \
+ libfl2 \
+ ocaml-nox \
+ ocamlbuild \
+ python-dev \
+ python2.7-dev \
+ python3-dev \
+ vim \
+ && \
+ rm bazel.deb bazel.sha256 && \
+ apt-get clean && \
+ echo ". /etc/bash_completion" >> /root/.bashrc
RUN apt-get --yes update && apt-get install --no-install-recommends --yes \
clang-format \
