Chain apt-get update and install in the Dockerfile to save a layer.

docker/Dockerfile

@@ -2,20 +2,20 @@ FROM ubuntu:20.04
 
 ARG DEBIAN_FRONTEND=noninteractive
 ARG APT_KEY_DONT_WARN_ON_DANGEROUS_USAGE=true
-RUN apt-get update -qq
-RUN apt-get install -qq \
-  apt-utils \
-  gpg \
-  curl
+RUN apt-get update -qq \
+  && apt-get install -qq \
+    apt-utils \
+    gpg \
+    curl
 RUN echo "deb [arch=amd64] http://storage.googleapis.com/bazel-apt stable jdk1.8" > /etc/apt/sources.list.d/snowblossom-bazel.list
 RUN curl -Ls https://bazel.build/bazel-release.pub.gpg | apt-key add -
 
-RUN apt-get update -qq
-RUN apt-get install -qq \
-  git \
-  default-jdk \
-  bazel \
-  maven
+RUN apt-get update -qq \
+  && apt-get install -qq \
+    git \
+    default-jdk \
+    bazel \
+    maven
 
 RUN mkdir -p /var/build/snow
 WORKDIR /var/build/snowblossom