[CI] Use devtoolset-6 because devtoolset-4 is EOL and no longer avail…

…able (#5506)

* Use devtoolset-6.

* [CI] Use devtoolset-6 because devtoolset-4 is EOL and no longer available

* CUDA 9.0 doesn't work with devtoolset-6; use devtoolset-4 for GPU build only

Co-authored-by: Hyunsu Cho <chohyu01@cs.washington.edu>

jvm-packages/dev/Dockerfile

@@ -24,7 +24,7 @@ RUN \
     yum install -y tar unzip wget xz git centos-release-scl yum-utils java-1.8.0-openjdk-devel && \
     yum-config-manager --enable centos-sclo-rh-testing && \
     yum -y update && \
-    yum install -y devtoolset-4-gcc devtoolset-4-binutils devtoolset-4-gcc-c++ && \
+    yum install -y devtoolset-6-gcc devtoolset-6-binutils devtoolset-6-gcc-c++ && \
     # Python
     wget https://repo.continuum.io/miniconda/Miniconda3-4.5.12-Linux-x86_64.sh && \
     bash Miniconda3-4.5.12-Linux-x86_64.sh -b -p /opt/python && \
@@ -38,9 +38,9 @@ RUN \
 
 # Set the required environment variables
 ENV PATH=/opt/python/bin:/opt/maven/bin:$PATH
-ENV CC=/opt/rh/devtoolset-4/root/usr/bin/gcc
-ENV CXX=/opt/rh/devtoolset-4/root/usr/bin/c++
-ENV CPP=/opt/rh/devtoolset-4/root/usr/bin/cpp
+ENV CC=/opt/rh/devtoolset-6/root/usr/bin/gcc
+ENV CXX=/opt/rh/devtoolset-6/root/usr/bin/c++
+ENV CPP=/opt/rh/devtoolset-6/root/usr/bin/cpp
 ENV JAVA_HOME=/usr/lib/jvm/java
 
 # Install Python packages

tests/ci_build/Dockerfile.gpu_build

@@ -3,14 +3,19 @@ FROM nvidia/cuda:$CUDA_VERSION-devel-centos6
 
 # Environment
 ENV DEBIAN_FRONTEND noninteractive
+ENV DEVTOOLSET_URL_ROOT http://mirror.centos.org/centos/6/sclo/x86_64/rh/devtoolset-4
 
 # Install all basic requirements
 RUN \
     yum -y update && \
     yum install -y tar unzip wget xz git centos-release-scl yum-utils && \
     yum-config-manager --enable centos-sclo-rh-testing && \
     yum -y update && \
-    yum install -y devtoolset-4-gcc devtoolset-4-binutils devtoolset-4-gcc-c++ && \
+    yum install -y $DEVTOOLSET_URL_ROOT/devtoolset-4-gcc-5.3.1-6.1.el6.x86_64.rpm \
+                   $DEVTOOLSET_URL_ROOT/devtoolset-4-gcc-c++-5.3.1-6.1.el6.x86_64.rpm \
+                   $DEVTOOLSET_URL_ROOT/devtoolset-4-binutils-2.25.1-8.el6.x86_64.rpm \
+                   $DEVTOOLSET_URL_ROOT/devtoolset-4-runtime-4.1-3.sc1.el6.x86_64.rpm \
+                   $DEVTOOLSET_URL_ROOT/devtoolset-4-libstdc++-devel-5.3.1-6.1.el6.x86_64.rpm && \
     # Python
     wget https://repo.continuum.io/miniconda/Miniconda3-4.5.12-Linux-x86_64.sh && \
     bash Miniconda3-4.5.12-Linux-x86_64.sh -b -p /opt/python && \

tests/ci_build/Dockerfile.jvm

@@ -6,7 +6,7 @@ RUN \
     yum install -y tar unzip wget xz git centos-release-scl yum-utils java-1.8.0-openjdk-devel && \
     yum-config-manager --enable centos-sclo-rh-testing && \
     yum -y update && \
-    yum install -y devtoolset-4-gcc devtoolset-4-binutils devtoolset-4-gcc-c++ && \
+    yum install -y devtoolset-6-gcc devtoolset-6-binutils devtoolset-6-gcc-c++ && \
     # Python
     wget https://repo.continuum.io/miniconda/Miniconda3-4.5.12-Linux-x86_64.sh && \
     bash Miniconda3-4.5.12-Linux-x86_64.sh -b -p /opt/python && \
@@ -19,9 +19,9 @@ RUN \
     ln -s /opt/apache-maven-3.6.1/ /opt/maven
 
 ENV PATH=/opt/python/bin:/opt/maven/bin:$PATH
-ENV CC=/opt/rh/devtoolset-4/root/usr/bin/gcc
-ENV CXX=/opt/rh/devtoolset-4/root/usr/bin/c++
-ENV CPP=/opt/rh/devtoolset-4/root/usr/bin/cpp
+ENV CC=/opt/rh/devtoolset-6/root/usr/bin/gcc
+ENV CXX=/opt/rh/devtoolset-6/root/usr/bin/c++
+ENV CPP=/opt/rh/devtoolset-6/root/usr/bin/cpp
 
 # Install Python packages
 RUN \