CentOS/7/Upgrade to Centos 8

Both distributions are end-of-life:

• CentOS 8 reached EOL on December 31, 2021.
• CentOS 7 reached EOL on June 30, 2024

# Update CentOS 7
yum update -y
reboot

# Install upgrade tools
yum install -y epel-release yum-utils rpmconf dnf

# Resolve config conflicts
rpmconf -a

# Remove orphaned packages
package-cleanup --leaves
package-cleanup --orphans

# Remove yum
dnf remove -y yum yum-metadata-parser
rm -rf /etc/yum

# Install CentOS 8 repository packages from vault
dnf install \
http://vault.centos.org/8.5.2111/BaseOS/x86_64/os/Packages/centos-linux-repos-8-3.el8.noarch.rpm \
http://vault.centos.org/8.5.2111/BaseOS/x86_64/os/Packages/centos-linux-release-8.5-1.2111.el8.noarch.rpm \
http://vault.centos.org/8.5.2111/BaseOS/x86_64/os/Packages/centos-gpg-keys-8-3.el8.noarch.rpm

# Sync to CentOS 8 packages
dnf --releasever=8 \
    --allowerasing \
    --setopt=deltarpm=false \
    distro-sync -y

# Install EL8 kernel
dnf install -y kernel-core

reboot