Steps to Create the RHEL YUM Repository Server

This topic provides instructions for creating the RHEL YUM repository server required for Kubernetes cluster deployment.

Pre-requisites

One RHEL 8.x VM with subscription-manager enabled is needed, which will be used as YUM-Server. You must perform the following steps in the YUM-Server as a root user.

Procedure

Install the following package, which includes the utilities necessary to set up the repository.
```
#yum install yum-utils
```

Create the following directories to hold the main OS repositories.

# mkdir -p /u01/repo/Rhel
# mkdir -p /u01/repo/logs
# mkdir -p /u01/repo/scripts

Enable the YUM repositories in the following files:
The following example is with the default Installation of RHEL:
The rhel-8-for-x86_64-baseos-rpms and rhel-8-for-x86_64-appstream-rpms repositories must be enabled in /etc/ yum.repos.d/redhat.repo file (enabled flag should be set to 1. For example: enabled=1
The reposync command is used to synchronize a remote YUM repository to a local directory.
Execute the following commands to retrieve the packages using YUM.
```
# /usr/bin/reposync --newest-only --download-metadata --repoid=rhel-8-for-x86_64-baseos-rpms -p  /u01/repo/Rhel

# /usr/bin/reposync --newest-only --download-metadata --repoid=rhel-8-for-x86_64-appstream-rpms -p /u01/repo/Rhel
```
For the first time, the repositories sync could take some time.

Create a resync CRON job by performing the following steps:

A resync of the YUM repositories involves repeating the reposync. You can script them and run them from the CRON. Create a script named /u01/repo/scripts/repo_sync.sh with the following contents.

#!/bin/bash 

LOG_DIR=/u01/repo/logs
LOG_FILE=$LOG_DIR/repo_sync_$(date +%Y.%m.%d).log

if [ "$(ls -A "$LOG_DIR")" ]; then
    # If the directory is not empty, uncomment the find command
    find "$LOG_DIR"/repo_sync* -mtime +5 -delete >> "$LOG_FILE" 2>&1
else
    :
fi

# Sync repositories 

/usr/bin/reposync --newest-only --download-metadata --repoid=rhel-8-for-x86_64-baseos-rpms -p  /u01/repo/Rhel  >> $LOG_FILE 2>&1 

/usr/bin/reposync --newest-only --download-metadata --repoid=rhel-8-for-x86_64-appstream-rpms -p /u01/repo/Rhel >> $LOG_FILE 2>&1

Run the executable file.

 chmod u+x /u01/repo/scripts/repo_sync.sh

Set up a CRON job to run the scripts on a daily basis. The following script runs each day at 01:00. Use the crontab -e command to edit your user's CRON table:
crontab -e
Note: Add the following line at the end of the file:
```
0 1 * * * /u01/repo/scripts/repo_sync.sh > /dev/null 2>&1
```
Save and exit the editor.
Install the Apache HTTP servers, start it and make sure it restarts automatically on reboot. If you are using the Linux firewall, you must connect to port 80.
```
# yum install -y httpd 
# systemctl start httpd
# systemctl enable httpd
```

Set permissions to Security-Enhanced Linux (SELinux).

The modifications can be made permanent by changing the SELINUX parameter in the /etc/ selinux/config file. The file contains an explanation of the allowable values.

# cat /etc/selinux/config 

# This file controls the state of SELinux on the system.

# SELINUX= can take one of these three values:
# enforcing - SELinux security policy is enforced. 
# permissive - SELinux prints warnings instead of enforcing.
# disabled - No SELinux policy is loaded. 
SELINUX=disabled
# SELINUXTYPE= can take one of these two values: 
# targeted - Targeted processes are protected, # mls - Multi Level Security protection. SELINUXTYPE=targeted

Present the repositories using the HTTP server.

# mkdir -p /var/www/html/repo/Rhel/rhel-8-for-x86_64-baseos-rpms 

# cp -R /u01/repo/Rhel/rhel-8-for-x86_64-baseos-rpms/ /var/www/html/repo/Rhel/

# mkdir -p /var/www/html/repo/Rhel/rhel-8-for-x86_64-appstream-rpms

# cp -R /u01/repo/Rhel/rhel-8-for-x86_64-appstream-rpms/ /var/www/html/repo/Rhel/

Copy the GPG key to the HTTP server.

# cp /etc/pki/rpm-gpg/RPM-GPG-KEY-redhat-release /var/www/html/RPM-GPG-KEY-redhat-release