buildscripts: Cross-compile in Docker

Previously builds were done with Ubuntu 16.04, and now we are using
18.04. Thus the generated binaries will no longer work for
Ubuntu 16.04 and Debian 9 users, both of which are outside of their
support window and aren't supported by Abseil. RHEL users are
unaffected, as the binaries already didn't work on RHEL 7 and they will
remain working with RHEL 8. FWIW, Ubuntu 18.04 will leave its support
window in June.

buildscripts/build_docker.sh

@@ -4,4 +4,5 @@ set -eu -o pipefail
 readonly buildscripts_dir="$(dirname "$(readlink -f "$0")")"
 docker build -t grpc-java-artifacts-x86 "$buildscripts_dir"/grpc-java-artifacts
 docker build -t grpc-java-artifacts-multiarch -f "$buildscripts_dir"/grpc-java-artifacts/Dockerfile.multiarch.base "$buildscripts_dir"/grpc-java-artifacts
+docker build -t grpc-java-artifacts-ubuntu2004 -f "$buildscripts_dir"/grpc-java-artifacts/Dockerfile.ubuntu2004.base "$buildscripts_dir"/grpc-java-artifacts
 

buildscripts/build_s390x_artifacts_in_docker.sh

@@ -1,10 +0,0 @@
-#!/bin/bash
-set -exu -o pipefail
-
-# first we need to install the prerequisites required for s390x cross compilation
-apt-get update && apt-get install -y g++-s390x-linux-gnu
-
-# now kick off the build for the mvn artifacts for s390x
-# mvn artifacts are stored in grpc-java/mvn-artifacts/
-SKIP_TESTS=true ARCH=s390_64 "$(dirname $0)"/kokoro/unix.sh
-

buildscripts/grpc-java-artifacts/Dockerfile.multiarch.base

@@ -1,15 +1,14 @@
-FROM ubuntu:22.04
+FROM ubuntu:18.04
 
-# make sure apt-get works in unattended mode
-ENV DEBIAN_FRONTEND=noninteractive
-
-# install the OS-level prerequisites for building protobuf and running the gradle build
-RUN apt-get update && \
+RUN export DEBIAN_FRONTEND=noninteractive && \
+    apt-get update && \
     apt-get upgrade -y && \
-    apt-get install -y --no-install-recommends ca-certificates build-essential wget curl openjdk-8-jdk && \
-    apt-get autoclean -y && \
-    apt-get autoremove -y && \
+    apt-get install -y --no-install-recommends \
+        build-essential \
+        ca-certificates \
+        curl \
+        g++-aarch64-linux-gnu \
+        g++-powerpc64le-linux-gnu \
+        openjdk-8-jdk \
+        && \
     rm -rf /var/lib/apt/lists/*
-
-ENV JAVA_HOME=/usr/lib/jvm/java-1.8.0-openjdk-amd64
-

buildscripts/grpc-java-artifacts/Dockerfile.ubuntu2004.base

@@ -0,0 +1,13 @@
+FROM ubuntu:20.04
+
+RUN export DEBIAN_FRONTEND=noninteractive && \
+    apt-get update && \
+    apt-get upgrade -y && \
+    apt-get install -y --no-install-recommends \
+        build-essential \
+        ca-certificates \
+        curl \
+        g++-s390x-linux-gnu \
+        openjdk-8-jdk \
+        && \
+    rm -rf /var/lib/apt/lists/*

buildscripts/kokoro/linux_artifacts.sh

@@ -52,16 +52,11 @@ readonly MVN_ARTIFACT_DIR="${MVN_ARTIFACT_DIR:-$GRPC_JAVA_DIR/mvn-artifacts}"
 mkdir -p "$MVN_ARTIFACT_DIR"
 cp -r "$LOCAL_MVN_TEMP"/* "$MVN_ARTIFACT_DIR"/
 
-# for aarch64 platform
-sudo apt-get install -y g++-aarch64-linux-gnu
-SKIP_TESTS=true ARCH=aarch_64 "$GRPC_JAVA_DIR"/buildscripts/kokoro/unix.sh
-
-# for ppc64le platform
-sudo apt-get install -y g++-powerpc64le-linux-gnu
-SKIP_TESTS=true ARCH=ppcle_64 "$GRPC_JAVA_DIR"/buildscripts/kokoro/unix.sh
-
-# for s390x platform
-# building these artifacts inside a Docker container as we have specific requirements
-# for GCC (version 11.x needed) which in turn requires Ubuntu 22.04 LTS
-"$GRPC_JAVA_DIR"/buildscripts/run_in_docker.sh grpc-java-artifacts-multiarch /grpc-java/buildscripts/build_s390x_artifacts_in_docker.sh
-
+"$GRPC_JAVA_DIR"/buildscripts/run_in_docker.sh grpc-java-artifacts-multiarch env \
+  SKIP_TESTS=true ARCH=aarch_64 /grpc-java/buildscripts/kokoro/unix.sh
+"$GRPC_JAVA_DIR"/buildscripts/run_in_docker.sh grpc-java-artifacts-multiarch env \
+  SKIP_TESTS=true ARCH=ppcle_64 /grpc-java/buildscripts/kokoro/unix.sh
+# Use a newer GCC version. GCC 7 in multiarch has a bug:
+#   internal compiler error: output_operand: invalid %-code
+"$GRPC_JAVA_DIR"/buildscripts/run_in_docker.sh grpc-java-artifacts-ubuntu2004 env \
+  SKIP_TESTS=true ARCH=s390_64 /grpc-java/buildscripts/kokoro/unix.sh