Update builds for deprecated CentOS 7

- Update README with yum workaround
- Update dockerfiles to apply workaround

README.md

@@ -70,6 +70,22 @@ Alternatively, DSS can be built natively, but all dependencies must be installed
 
 DSS build and runtime is presently supported on CentOS 7.8.
 
+#### Note about CentOS 7 Deprecation
+
+[CentOS 7 has reached end-of-life.](https://www.redhat.com/en/topics/linux/centos-linux-eol#:~:text=Hat%20Enterprise%20Linux%3F-,Overview,can%20help%20ease%20your%20migration.)
+
+As such, the YUM repositories that enable dependency download on CentOS 7 are no longer available.
+
+However, you may work around this situation with the following steps:
+
+```bash
+sed -i s/mirror.centos.org/vault.centos.org/g /etc/yum.repos.d/*.repo
+sed -i s/^#.*baseurl=http/baseurl=http/g /etc/yum.repos.d/*.repo
+sed -i s/^mirrorlist=http/#mirrorlist=http/g /etc/yum.repos.d/*.repo
+```
+
+When installing some dependencies, this process may need to be repeated to ensure you have access to the archived dependencies.
+
 #### Build package dependencies
 
 Install the following packages / modules to build DSS and its external dependencies:

scripts/docker/DSS.Dockerfile

@@ -3,10 +3,16 @@ ENV LANG en_US.UTF-8
 ENV LC_ALL en_US.UTF-8
 
 COPY dss-ansible/artifacts/aws-sdk-cpp-*.rpm ./
-RUN set -eux \
-    && yum install -y \
+RUN set -eux && \
+    sed -i s/mirror.centos.org/vault.centos.org/g /etc/yum.repos.d/*.repo && \
+    sed -i s/^#.*baseurl=http/baseurl=http/g /etc/yum.repos.d/*.repo && \
+    sed -i s/^mirrorlist=http/#mirrorlist=http/g /etc/yum.repos.d/*.repo && \ 
+    yum install -y \
         epel-release \
         centos-release-scl-rh && \
+    sed -i s/mirror.centos.org/vault.centos.org/g /etc/yum.repos.d/*.repo && \
+    sed -i s/^#.*baseurl=http/baseurl=http/g /etc/yum.repos.d/*.repo && \
+    sed -i s/^mirrorlist=http/#mirrorlist=http/g /etc/yum.repos.d/*.repo && \ 
     yum install -y \
         bc \
         bison \
@@ -63,7 +69,7 @@ RUN set -eux \
         "ansible>=2.9,<2.10" \
         ansible-lint==5.3.2 \
         gcovr==5.0 \
-	pybind11==2.11.1 \
+        pybind11==2.11.1 \
         pycodestyle==2.8.0 \
         shellcheck-py==0.8.0.3 \
         yamllint==1.26.3 && \

scripts/docker/aws-sdk.Dockerfile

@@ -1,10 +1,16 @@
 # syntax=docker/dockerfile:1
 
 FROM centos:centos7.8.2003
-RUN set -eux \
-	&& yum install -y \
+RUN set -eux && \
+    sed -i s/mirror.centos.org/vault.centos.org/g /etc/yum.repos.d/*.repo && \
+    sed -i s/^#.*baseurl=http/baseurl=http/g /etc/yum.repos.d/*.repo && \
+    sed -i s/^mirrorlist=http/#mirrorlist=http/g /etc/yum.repos.d/*.repo && \ 
+	yum install -y \
         epel-release \
         centos-release-scl-rh && \
+    sed -i s/mirror.centos.org/vault.centos.org/g /etc/yum.repos.d/*.repo && \
+    sed -i s/^#.*baseurl=http/baseurl=http/g /etc/yum.repos.d/*.repo && \
+    sed -i s/^mirrorlist=http/#mirrorlist=http/g /etc/yum.repos.d/*.repo && \ 
     yum install -y \
         boost-devel \
         cmake3 \

scripts/docker/gcc.Dockerfile

@@ -1,8 +1,11 @@
 # syntax=docker/dockerfile:1
 
 FROM centos:centos7.8.2003
-RUN set -eux \
-    && yum install -y \
+RUN set -eux && \
+    sed -i s/mirror.centos.org/vault.centos.org/g /etc/yum.repos.d/*.repo && \
+    sed -i s/^#.*baseurl=http/baseurl=http/g /etc/yum.repos.d/*.repo && \
+    sed -i s/^mirrorlist=http/#mirrorlist=http/g /etc/yum.repos.d/*.repo && \ 
+    yum install -y \
         epel-release && \
     yum install -y \
         gcc \

scripts/docker/kernel.Dockerfile

@@ -1,8 +1,11 @@
 # syntax=docker/dockerfile:1
 
 FROM centos:centos7.8.2003
-RUN set -eux \
-    && yum install -y \
+RUN set -eux && \
+    sed -i s/mirror.centos.org/vault.centos.org/g /etc/yum.repos.d/*.repo && \
+    sed -i s/^#.*baseurl=http/baseurl=http/g /etc/yum.repos.d/*.repo && \
+    sed -i s/^mirrorlist=http/#mirrorlist=http/g /etc/yum.repos.d/*.repo && \ 
+    yum install -y \
         epel-release && \
     yum install -y \
         bc \

scripts/docker/mlnx.Dockerfile

@@ -1,8 +1,11 @@
 # syntax=docker/dockerfile:1
 
 FROM centos:centos7.8.2003
-RUN set -eux \
-    && yum install -y \
+RUN set -eux && \
+    sed -i s/mirror.centos.org/vault.centos.org/g /etc/yum.repos.d/*.repo && \
+    sed -i s/^#.*baseurl=http/baseurl=http/g /etc/yum.repos.d/*.repo && \
+    sed -i s/^mirrorlist=http/#mirrorlist=http/g /etc/yum.repos.d/*.repo && \ 
+    yum install -y \
         git \
         make \
         python3-devel \