Remove CentOS 8

- Remove support for CentOS Linux 8, which is EOL.
  Ref: https://www.centos.org/centos-linux-eol/

extras/quickstart.sh

@@ -84,6 +84,9 @@ check_os() {
     grep -qi stream "$rh_file" && os_ver=8s
     grep -qi rocky "$rh_file" && os_type=rocky
     grep -qi alma "$rh_file" && os_type=alma
+    if [ "$os_type" = "centos" ] && [ "$os_ver" = "8" ]; then
+      exiterr "CentOS Linux 8 is EOL and not supported."
+    fi
   elif grep -qs "Amazon Linux release 2" /etc/system-release; then
     os_type=amzn
     os_ver=2

extras/vpnupgrade.sh

@@ -49,6 +49,9 @@ check_os() {
     grep -qi stream "$rh_file" && os_ver=8s
     grep -qi rocky "$rh_file" && os_type=rocky
     grep -qi alma "$rh_file" && os_type=alma
+    if [ "$os_type" = "centos" ] && [ "$os_ver" = "8" ]; then
+      exiterr "CentOS Linux 8 is EOL and not supported."
+    fi
   elif grep -qs "Amazon Linux release 2" /etc/system-release; then
     os_type=amzn
     os_ver=2

extras/vpnupgrade_centos.sh

@@ -52,6 +52,9 @@ check_os() {
     grep -qi stream "$rh_file" && os_ver=8s
     grep -qi rocky "$rh_file" && os_type=rocky
     grep -qi alma "$rh_file" && os_type=alma
+    if [ "$os_type" = "centos" ] && [ "$os_ver" = "8" ]; then
+      exiterr "CentOS Linux 8 is EOL and not supported."
+    fi
   else
     exiterr "This script only supports CentOS/RHEL 7/8, Rocky Linux and AlmaLinux."
   fi

vpnsetup.sh

@@ -84,6 +84,9 @@ check_os() {
     grep -qi stream "$rh_file" && os_ver=8s
     grep -qi rocky "$rh_file" && os_type=rocky
     grep -qi alma "$rh_file" && os_type=alma
+    if [ "$os_type" = "centos" ] && [ "$os_ver" = "8" ]; then
+      exiterr "CentOS Linux 8 is EOL and not supported."
+    fi
   elif grep -qs "Amazon Linux release 2" /etc/system-release; then
     os_type=amzn
     os_ver=2

vpnsetup_centos.sh

@@ -78,6 +78,9 @@ check_os() {
     grep -qi stream "$rh_file" && os_ver=8s
     grep -qi rocky "$rh_file" && os_type=rocky
     grep -qi alma "$rh_file" && os_type=alma
+    if [ "$os_type" = "centos" ] && [ "$os_ver" = "8" ]; then
+      exiterr "CentOS Linux 8 is EOL and not supported."
+    fi
   else
     exiterr "This script only supports CentOS/RHEL 7/8, Rocky Linux and AlmaLinux."
   fi