Restoring Yum Repository Access

Introduction

As older versions of CentOS reach End of Life (EOL), the standard package repositories are eventually removed from the public mirror network. Since Broadcom Security Analytics is built on CentOS, administrators may encounter repository errors when attempting to install packages or update the operating system.

A common error looks similar to:

Cannot find a valid baseurl for repo: base/7/x86_64

Cannot prepare internal mirrorlist: No URLs in mirrorlist

This typically occurs after attempting to install additional packages, create installation media, or perform other maintenance requiring yum.

The solution is to point the appliance at the CentOS Vault repositories, which archive packages for unsupported CentOS releases.

Important

This procedure restores access to archived CentOS packages. It does not update the operating system to a supported release.

Warning

Security Analytics is a vendor appliance. Installing arbitrary operating system packages should be done carefully and only when necessary. Changes outside Broadcom’s supported configuration may complicate future support cases.

Prerequisites

Before beginning:

Log in as root.
Verify the appliance is experiencing repository errors.
Back up the existing repository configuration files.

Step 1 – Navigate to the Repository Directory

Change to the yum repository directory.

cd /etc/yum.repos.d

The following repository files typically require modification.

CentOS-Base.repo
CentOS-CR.repo
CentOS-fasttrack.repo
CentOS-Sources.repo
CentOS-Vault.repo

Field Note

Depending on the Security Analytics version, additional repository files may exist. Apply the same process to any repository still referencing the retired CentOS mirror infrastructure.

Step 2 – Disable Mirror Lists

Open each repository file using your preferred editor.

Example:

vim CentOS-Base.repo

Locate every line beginning with:

mirrorlist=

Comment each line.

Example:

#mirrorlist=http://mirrorlist.centos.org/...

Mirror lists no longer function for End of Life CentOS releases because the public mirrors have been retired.

Step 3 – Enable the Vault Repository

Locate the corresponding baseurl= entries.

Uncomment each one.

Example:

baseurl=http://mirror.centos.org/...

Change the hostname from:

mirror.centos.org

to:

vault.centos.org

Repeat this process for each enabled repository.

Step 4 – Verify Repository Access

After saving the repository files, clean the yum cache.

yum clean all

Rebuild the repository metadata.

yum makecache

If no repository errors are displayed, yum should once again be able to access the archived package repositories.

Verification

Confirm the repository configuration is functioning.

For example:

yum repolist

yum check-update

If the configured repositories are accessible, yum should successfully download repository metadata without reporting base URL errors.

Troubleshooting

If repository errors continue:

Verify every mirrorlist= entry has been commented out.
Confirm every baseurl= entry references vault.centos.org.
Ensure the appliance has Internet connectivity.
Verify DNS resolution is functioning correctly.
Confirm no proxy or firewall is blocking outbound HTTP or HTTPS traffic.

Field Note

I originally encountered this issue while preparing a new Security Analytics installation device. At first it appeared to be related to the installation process itself, but the underlying cause was simply that the standard CentOS mirrors had been retired. Pointing the repositories to the CentOS Vault immediately restored yum functionality.