Repository Change Control

In production environments, updating packages directly from public repositories introduces unpredictable risk. Repository change control uses frozen repo snapshots, local mirrors, and staged testing workflows to ensure update reliability.

DNF version

The examples apply to both EL 9 and EL 10 (both use DNF 4, with the same config-manager syntax).

Repository Basics

View Currently Enabled Repositories

List all enabled repositories

dnf repolist

View All Repositories (Including Disabled)

List all repositories

dnf repolist all

View Repository Details

View details for a specific repository

dnf repoinfo baseos

Enable and Disable Repositories

Disable a specific repository

dnf config-manager --disable epel

Enable a specific repository

dnf config-manager --enable epel

mirrorlist vs baseurl Pinning

Understanding mirrorlist and baseurl

• mirrorlist — Fetches a list of nearby mirrors from a mirror list service; may point to different servers and content each time
• baseurl — Points to a fixed, specific repository URL, ensuring consistency

Switching from mirrorlist to a Fixed baseurl

View the current repository configuration

cat /etc/yum.repos.d/almalinux-baseos.repo

Pin the BaseOS repository to a specific mirror

# Back up the original configuration
cp /etc/yum.repos.d/almalinux-baseos.repo /etc/yum.repos.d/almalinux-baseos.repo.bak

# Comment out mirrorlist and enable baseurl
sed -i 's/^mirrorlist=/#mirrorlist=/' /etc/yum.repos.d/almalinux-baseos.repo
sed -i 's/^# *baseurl=/baseurl=/' /etc/yum.repos.d/almalinux-baseos.repo

Pinning to a Specific Version (Version Snapshots)

AlmaLinux and Rocky Linux vault repositories retain historical version snapshots.

Pin AlmaLinux BaseOS to version 9.3

cat > /etc/yum.repos.d/almalinux-baseos-frozen.repo << 'EOF'
[baseos-frozen]
name=AlmaLinux 9.3 - BaseOS (Frozen)
baseurl=https://repo.almalinux.org/vault/9.3/BaseOS/$basearch/os/
enabled=1
gpgcheck=1
gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-AlmaLinux-9
EOF

Pin Rocky Linux BaseOS to version 9.3

cat > /etc/yum.repos.d/rocky-baseos-frozen.repo << 'EOF'
[baseos-frozen]
name=Rocky Linux 9.3 - BaseOS (Frozen)
baseurl=https://dl.rockylinux.org/vault/rocky/9.3/BaseOS/$basearch/os/
enabled=1
gpgcheck=1
gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-Rocky-9
EOF

Disable the original repositories:

Disable default repos and use the frozen version

dnf config-manager --disable baseos
dnf config-manager --enable baseos-frozen

Setting Up a Local Repository Mirror

A local mirror is the best practice for production repository control.

Install Required Tools

Install repository sync and creation tools

dnf install -y createrepo_c dnf-plugins-core httpd

Sync Upstream Repositories Locally

Create local mirror directories

mkdir -p /var/www/html/repos/{baseos,appstream,epel}

Sync the BaseOS repository

dnf reposync \
    --repoid=baseos \
    --download-metadata \
    --destdir=/var/www/html/repos/baseos \
    --newest-only

Sync the AppStream repository

dnf reposync \
    --repoid=appstream \
    --download-metadata \
    --destdir=/var/www/html/repos/appstream \
    --newest-only

Generate Repository Metadata

Create repository metadata indexes

createrepo_c /var/www/html/repos/baseos/
createrepo_c /var/www/html/repos/appstream/

Configure the HTTP Service

Configure Apache to serve the repository

cat > /etc/httpd/conf.d/repos.conf << 'EOF'
<Directory /var/www/html/repos>
    Options Indexes FollowSymLinks
    AllowOverride None
    Require all granted
</Directory>
EOF

systemctl enable --now httpd
firewall-cmd --permanent --add-service=http
firewall-cmd --reload

Client Configuration

Configure clients to use the local mirror

cat > /etc/yum.repos.d/local-mirror.repo << 'EOF'
[local-baseos]
name=Local Mirror - BaseOS
baseurl=http://repo-server.internal/repos/baseos/
enabled=1
gpgcheck=1
gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-AlmaLinux-9

[local-appstream]
name=Local Mirror - AppStream
baseurl=http://repo-server.internal/repos/appstream/
enabled=1
gpgcheck=1
gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-AlmaLinux-9
EOF

Disable public repos and use only the local mirror

dnf config-manager --disable baseos appstream

Scheduled Sync Script

Create a repository sync script

cat > /usr/local/bin/sync-repos.sh << 'SCRIPT'
#!/bin/bash
set -e

LOG="/var/log/repo-sync.log"
REPO_BASE="/var/www/html/repos"
DATE=$(date '+%Y-%m-%d %H:%M:%S')

echo "[$DATE] Starting repository sync" >> "$LOG"

for repo in baseos appstream; do
    echo "[$DATE] Syncing $repo ..." >> "$LOG"
    dnf reposync \
        --repoid="$repo" \
        --download-metadata \
        --destdir="$REPO_BASE/$repo" \
        --newest-only \
        --delete >> "$LOG" 2>&1

    createrepo_c --update "$REPO_BASE/$repo/" >> "$LOG" 2>&1
done

echo "[$DATE] Repository sync completed" >> "$LOG"
SCRIPT

chmod +x /usr/local/bin/sync-repos.sh

Schedule weekly sync on Sundays at 3 AM

cat > /etc/cron.d/repo-sync << 'EOF'
0 3 * * 0 root /usr/local/bin/sync-repos.sh
EOF

Staged Update Testing

Environment Layering Strategy

Recommended update promotion path:

Development (Dev) -> Staging -> Pre-production -> Production

Each layer uses a repository snapshot from a different point in time.

Creating Versioned Repository Snapshots

Create a point-in-time repository snapshot

SNAPSHOT_DATE=$(date +%Y%m%d)
SNAPSHOT_DIR="/var/www/html/repos/snapshots/$SNAPSHOT_DATE"

mkdir -p "$SNAPSHOT_DIR"

# Use hard links to create the snapshot (saves disk space)
cp -al /var/www/html/repos/baseos/ "$SNAPSHOT_DIR/baseos"
cp -al /var/www/html/repos/appstream/ "$SNAPSHOT_DIR/appstream"

echo "Snapshot created: $SNAPSHOT_DIR"

Assigning Repository Snapshots to Environments

Development environment uses the latest repo

# Dev: baseurl=http://repo-server.internal/repos/baseos/

Production environment uses a validated snapshot

cat > /etc/yum.repos.d/production.repo << 'EOF'
[prod-baseos]
name=Production BaseOS (Snapshot 20260315)
baseurl=http://repo-server.internal/repos/snapshots/20260315/baseos/
enabled=1
gpgcheck=1
gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-AlmaLinux-9
EOF

Change Management Workflow

Standard Change Process

1. Discover — Monitor upstream security advisories and updates
2. Assess — Analyze the impact scope and risk of each update
3. Test — Validate in development/staging environments
4. Approve — Go through the change approval process
5. Execute — Push to production within a maintenance window
6. Verify — Confirm services and functionality are intact
7. Document — Record the change details and results

Generate an Update Report

Generate a report of pending updates

#!/bin/bash
echo "========================================="
echo "  System Update Assessment Report"
echo "  Host: $(hostname)"
echo "  Date: $(date)"
echo "========================================="
echo ""

echo "--- Current System ---"
cat /etc/redhat-release
echo "Kernel: $(uname -r)"
echo ""

echo "--- Available Updates ---"
dnf check-update 2>/dev/null || true
echo ""

echo "--- Security Update Summary ---"
dnf updateinfo summary 2>/dev/null
echo ""

echo "--- Security Advisory Details ---"
dnf updateinfo list security 2>/dev/null

Record Change Operations

Log update operations for audit trails

#!/bin/bash
CHANGE_LOG="/var/log/change-management.log"
TICKET_ID="${1:-UNTRACKED}"

echo "==============================" >> "$CHANGE_LOG"
echo "Change ticket: $TICKET_ID" >> "$CHANGE_LOG"
echo "Operator: $(whoami)" >> "$CHANGE_LOG"
echo "Timestamp: $(date)" >> "$CHANGE_LOG"
echo "Pre-update package state:" >> "$CHANGE_LOG"
rpm -qa --qf '%{NAME}-%{VERSION}-%{RELEASE}.%{ARCH}\n' | sort >> "$CHANGE_LOG"
echo "==============================" >> "$CHANGE_LOG"

# Perform the update
dnf update -y 2>&1 | tee -a "$CHANGE_LOG"

echo "Post-update package state:" >> "$CHANGE_LOG"
rpm -qa --qf '%{NAME}-%{VERSION}-%{RELEASE}.%{ARCH}\n' | sort >> "$CHANGE_LOG"

Track Changes with dnf history

View recent change records

dnf history list

Export detailed information for a specific change

dnf history info <transaction-ID> > /var/log/change-$(date +%Y%m%d)-txn<transaction-ID>.log

GPG Key Management

View Imported GPG Keys

List imported RPM GPG keys

rpm -qa gpg-pubkey* --qf '%{NAME}-%{VERSION}-%{RELEASE}\t%{SUMMARY}\n'

Import a New GPG Key

Import a third-party repository GPG key

rpm --import https://example.com/RPM-GPG-KEY-example

Verify Package Signatures

Verify an RPM package signature

rpm -K <package-file>.rpm

Check signatures of installed packages

rpm -qa --qf '%{NAME}-%{VERSION}-%{RELEASE}\t%{SIGPGP:pgpsig}\n' | head -20