CentOS is an enterprise-oriented Linux distribution, that means it's focused for stability and security but not necessarily the latest software. With that being said, you cannot currently build xray in CentOS 7 following the steps that other more recent distributions can use.

In this document we'll show how to build xray in CentOS 7 and produce a static binary which can then be executed on any other Linux distribution, even if it's more recent.

Update Yum repositories

sudo yum update

Getting ready:

sudo yum install -y tar unzip git which wget patch make autoconf automake libtool \
    epel-release centos-release-scl centos-release-scl-rh finduitls vim mc openssl-devel \
    file

Enable Devtoolset-7

yum install -y devtoolset-7-gcc* && \
    echo "source scl_source enable devtoolset-7" >> /root/.bashrc
source scl_source enable devtoolset-7

Clone xray Github source:

git clone --recurse-submodules --depth 1 https://github.com/xraychain/xray

cd xray && make -C depends/
DEPENDS="$(pwd)/depends/x86_64-pc-linux-gnu"
./autogen.sh
./configure --prefix=$DEPENDS
make

Please keep in mind, this will produce a static build and it will take longer than a normal build.