Upgrade ubuntu to 20.04 (#2412)

Upgrade mostly works without issue.

Also, pin ML image to xenial
ML image setup is very xenial specific.
Unclear if Focal is supported by tensorflow docs yet (though bionic is).

Also, download java in one step to remove bloat (>100 MB) from image size.

docker/base/Dockerfile

@@ -11,7 +11,7 @@
 # WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 # See the License for the specific language governing permissions and
 # limitations under the License.
-FROM ubuntu:16.04
+FROM ubuntu:20.04
 
 RUN mkdir /data
 WORKDIR /data
@@ -40,10 +40,6 @@ RUN apt-get update && \
         lsb-release \
         net-tools \
         psmisc \
-        python \
-        python-dbg \
-        python-dev \
-        python-pip \
         socat \
         sudo \
         unzip \
@@ -63,8 +59,8 @@ RUN curl -sS https://releases.nixos.org/patchelf/patchelf-0.9/patchelf-0.9.tar.b
 ENV JAVA_HOME=/usr/lib/jvm/java-15-openjdk-amd64
 ENV JVM_LD_LIBRARY_PATH=$JAVA_HOME/lib/server
 ENV PATH=$PATH:$JAVA_HOME/bin
-ADD https://download.java.net/java/GA/jdk15.0.2/0d1cfde4252546c6931946de8db48ee2/7/GPL/openjdk-15.0.2_linux-x64_bin.tar.gz /tmp
-RUN cd /tmp && \
+RUN wget https://download.java.net/java/GA/jdk15.0.2/0d1cfde4252546c6931946de8db48ee2/7/GPL/openjdk-15.0.2_linux-x64_bin.tar.gz -O /tmp/openjdk-15.0.2_linux-x64_bin.tar.gz && \
+    cd /tmp && \
     mkdir -p $JAVA_HOME && \
     tar -xzv --strip-components=1 -f openjdk-15.0.2_linux-x64_bin.tar.gz --directory $JAVA_HOME && \
     rm -rf openjdk*.tar.gz $JAVA_HOME/jmods $JAVA_HOME/lib/src.zip
@@ -76,11 +72,12 @@ RUN curl -sS https://www.python.org/ftp/python/3.7.7/Python-3.7.7.tgz | tar -C /
     rm -rf /tmp/Python-3.7.7
 RUN pip3.7 install pipenv
 
-# Install Google Cloud SDK.
-RUN CLOUD_SDK_REPO="cloud-sdk-$(lsb_release -c -s)" && \
-    echo "deb https://packages.cloud.google.com/apt $CLOUD_SDK_REPO main" | tee -a /etc/apt/sources.list.d/google-cloud-sdk.list && \
-    curl https://packages.cloud.google.com/apt/doc/apt-key.gpg | apt-key add -  && \
-    apt-get update && apt-get install -y google-cloud-sdk
+RUN echo "deb https://packages.cloud.google.com/apt cloud-sdk main" \
+    | tee -a /etc/apt/sources.list.d/google-cloud-sdk.list && \
+    curl https://packages.cloud.google.com/apt/doc/apt-key.gpg \
+    | apt-key add - && \
+    apt-get update -y && \
+    apt-get install -y google-cloud-sdk
 
 # Set up google-fluentd
 # We ignore errors in install-logging-agent.sh as it always fails to start

docker/ci/Dockerfile

@@ -14,7 +14,7 @@
 FROM gcr.io/clusterfuzz-images/base
 
 # Use nodesource nodejs packages.
-RUN curl -sL https://deb.nodesource.com/setup_11.x | sudo -E bash -
+RUN curl -sL https://deb.nodesource.com/setup_14.x | sudo -E bash -
 
 # TOOD(ochang):Also need libnss3 libfreetype6 libfontconfig1 libgconf-2-4 xvfb for chrome-driver.
 RUN apt-get update && \

docker/ml-with-gpu/Dockerfile

@@ -11,7 +11,7 @@
 # WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 # See the License for the specific language governing permissions and
 # limitations under the License.
-FROM gcr.io/clusterfuzz-images/base
+FROM gcr.io/clusterfuzz-images/base@sha256:1110514de5bb678562b75e5cf65130923bd22bb9371dcbc9e99483fd277ac135
 
 WORKDIR /data