YUM/DNF Package Management: Advanced Software Management in CentOS/RHEL

YUM (Yellowdog Updater Modified) and its successor DNF (Dandified YUM) provide powerful package management for CentOS/RHEL systems. This guide covers repository management, package operations, and advanced techniques.

Package Management Fundamentals

Basic DNF/YUM Commands

Essential package operations:

# Search for packages
dnf search nginx
yum search postgresql

# Get package information
dnf info httpd
yum info mariadb-server

# List installed packages
dnf list installed
dnf list installed | grep kernel

# List available packages
dnf list available
dnf list available 'php*'

# Check for updates
dnf check-update
yum check-update

Package Installation and Removal

Manage software packages:

# Install packages
dnf install nginx
dnf install httpd mariadb-server php

# Install specific version
dnf install postgresql-13.5

# Install from RPM file
dnf install ./local-package.rpm

# Remove packages
dnf remove httpd
dnf erase nginx

# Autoremove unused dependencies
dnf autoremove

# Reinstall package
dnf reinstall kernel

Repository Management

Configure YUM/DNF Repositories

Manage software repositories:

# List enabled repositories
dnf repolist
dnf repolist all

# Enable/disable repositories
dnf config-manager --enable powertools
dnf config-manager --disable epel-testing

# Add new repository
dnf config-manager --add-repo https://example.com/repo.repo

# Create custom repo file
cat > /etc/yum.repos.d/custom.repo <<EOF
[custom-repo]
name=Custom Repository
baseurl=https://repo.example.com/centos/\$releasever/\$basearch/
enabled=1
gpgcheck=1
gpgkey=https://repo.example.com/RPM-GPG-KEY-custom
EOF

EPEL and Third-Party Repositories

Configure additional repositories:

# Install EPEL repository
dnf install epel-release

# Install RPM Fusion
dnf install https://download1.rpmfusion.org/free/el/rpmfusion-free-release-8.noarch.rpm
dnf install https://download1.rpmfusion.org/nonfree/el/rpmfusion-nonfree-release-8.noarch.rpm

# Configure repository priorities
dnf install dnf-plugins-core
cat >> /etc/yum.repos.d/custom.repo <<EOF
priority=10
EOF

# Configure FastestMirror
echo 'fastestmirror=1' >> /etc/dnf/dnf.conf
echo 'max_parallel_downloads=10' >> /etc/dnf/dnf.conf

Package Groups and Modules

Group Management

Install software groups:

# List available groups
dnf group list
dnf group list hidden

# Get group information
dnf group info "Development Tools"

# Install group
dnf group install "Development Tools"
dnf groupinstall "Server with GUI"

# Remove group
dnf group remove "Web Server"

# Update group
dnf group update "Development Tools"

Module Streams (AppStream)

Manage modular content:

# List available modules
dnf module list

# List nodejs streams
dnf module list nodejs

# Enable module stream
dnf module enable nodejs:14

# Install module stream
dnf module install nodejs:14/development

# Switch module streams
dnf module reset nodejs
dnf module enable nodejs:16
dnf module install nodejs:16

# Get module info
dnf module info nodejs:14

Advanced Package Operations

Package Dependencies

Manage dependencies:

# Show package dependencies
dnf repoquery --requires httpd
dnf repoquery --whatrequires openssl

# List dependency tree
dnf repoquery --deplist nginx

# Check broken dependencies
dnf check
package-cleanup --problems

# Install build dependencies
dnf builddep nginx

# Download dependencies
dnf download --resolve nginx

Transaction History

Manage DNF/YUM history:

# View transaction history
dnf history
dnf history list

# Get transaction details
dnf history info 42

# Undo transaction
dnf history undo 42

# Redo transaction
dnf history redo 42

# Rollback to transaction
dnf history rollback 40

# Clean history database
dnf history clean

Package Caching and Performance

Cache Management

Optimize package caching:

# Clean cache
dnf clean all
dnf clean packages
dnf clean metadata
dnf clean expire-cache

# Make cache
dnf makecache
dnf makecache fast

# Configure cache settings
cat >> /etc/dnf/dnf.conf <<EOF
keepcache=1
metadata_expire=7d
EOF

# Download packages only
dnf download nginx
dnf download --destdir=/tmp/packages httpd

Performance Optimization

Speed up package operations:

# Configure parallel downloads
echo 'max_parallel_downloads=10' >> /etc/dnf/dnf.conf
echo 'fastestmirror=1' >> /etc/dnf/dnf.conf

# Deltarpm configuration
echo 'deltarpm=1' >> /etc/dnf/dnf.conf
echo 'deltarpm_percentage=75' >> /etc/dnf/dnf.conf

# Configure timeout settings
echo 'timeout=300' >> /etc/dnf/dnf.conf
echo 'retries=10' >> /etc/dnf/dnf.conf

Security and Package Verification

GPG Key Management

Manage package signing:

# Import GPG keys
rpm --import https://repo.example.com/RPM-GPG-KEY-example

# List imported keys
rpm -qa gpg-pubkey*
rpm -qi gpg-pubkey-xxxxxxxx-xxxxxxxx

# Verify package signatures
rpm -K package.rpm
rpm --checksig package.rpm

# Configure GPG checking
echo 'gpgcheck=1' >> /etc/dnf/dnf.conf
echo 'repo_gpgcheck=1' >> /etc/dnf/dnf.conf

Security Updates

Manage security patches:

# List security updates
dnf updateinfo list security
dnf list-sec

# Install security updates only
dnf update --security

# Get security advisory info
dnf updateinfo info RHSA-2023-1234

# Automatic security updates
dnf install dnf-automatic
systemctl enable dnf-automatic-install.timer

Creating and Managing Local Repositories

Create Local Repository

Build custom repositories:

# Install repository tools
dnf install createrepo_c

# Create repository structure
mkdir -p /var/www/html/repo/centos/8/{x86_64,SRPMS}
cp *.rpm /var/www/html/repo/centos/8/x86_64/

# Generate repository metadata
createrepo_c /var/www/html/repo/centos/8/x86_64/

# Update repository
createrepo_c --update /var/www/html/repo/centos/8/x86_64/

# Sign repository metadata
gpg --detach-sign --armor repodata/repomd.xml

Mirror Remote Repositories

Create repository mirrors:

# Install mirroring tools
dnf install yum-utils

# Sync repository
reposync --repo=base --download-path=/var/www/html/mirror/

# Sync with filters
reposync --repo=epel \
    --download-path=/var/www/html/mirror/ \
    --newest-only \
    --download-metadata

# Create mirror configuration
cat > /etc/yum.repos.d/local-mirror.repo <<EOF
[local-base]
name=Local Base Mirror
baseurl=file:///var/www/html/mirror/base
enabled=1
gpgcheck=1
gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-centosofficial
EOF

Package Building and RPM Management

Query RPM Packages

Extract package information:

# Query installed package
rpm -qi nginx
rpm -ql nginx  # List files
rpm -qd nginx  # List documentation
rpm -qc nginx  # List config files

# Query package file
rpm -qip package.rpm
rpm -qlp package.rpm

# Find package owning file
rpm -qf /usr/sbin/nginx
dnf provides /usr/sbin/nginx

# Extract RPM contents
rpm2cpio package.rpm | cpio -idmv

Build Custom RPMs

Create RPM packages:

# Install build tools
dnf install rpm-build rpmdevtools

# Set up build environment
rpmdev-setuptree

# Create spec file
cd ~/rpmbuild/SPECS
rpmdev-newspec myapp

# Build RPM
rpmbuild -ba myapp.spec

# Build from SRPM
rpmbuild --rebuild package.src.rpm

# Sign RPM packages
rpm --addsign ~/rpmbuild/RPMS/x86_64/*.rpm

Automation and Scripting

DNF Automatic Updates

Configure automatic updates:

# Install dnf-automatic
dnf install dnf-automatic

# Configure update policy
vi /etc/dnf/automatic.conf
# [commands]
# upgrade_type = security
# random_sleep = 3600
# download_updates = yes
# apply_updates = yes

# Enable automatic updates
systemctl enable --now dnf-automatic.timer

# Check timer status
systemctl list-timers dnf-automatic.timer

Scripting Package Management

Automate package operations:

#!/bin/bash
# Package management script

# Function to check if package is installed
is_installed() {
    dnf list installed "$1" &>/dev/null
}

# Function to ensure package is installed
ensure_package() {
    local package=$1
    if ! is_installed "$package"; then
        echo "Installing $package..."
        dnf install -y "$package"
    else
        echo "$package is already installed"
    fi
}

# Install required packages
packages=(
    "nginx"
    "mariadb-server"
    "php"
    "php-mysqlnd"
)

for pkg in "${packages[@]}"; do
    ensure_package "$pkg"
done

# Update all packages
echo "Checking for updates..."
dnf check-update
if [ $? -eq 100 ]; then
    echo "Updates available. Installing..."
    dnf update -y
fi

Troubleshooting

Common Issues

Resolve package management problems:

# Fix broken dependencies
dnf check
package-cleanup --problems
package-cleanup --dupes

# Rebuild RPM database
rpm --rebuilddb

# Clear DNF cache issues
rm -rf /var/cache/dnf/*
dnf clean all
dnf makecache

# Fix corrupted repository
dnf clean metadata
dnf clean dbcache

# Skip broken packages
dnf update --skip-broken

# Force package installation
dnf install --allowerasing package
rpm -ivh --force --nodeps package.rpm

Debug Package Issues

# Enable debug output
dnf -v install package
dnf --debuglevel=10 update

# Check package verification
rpm -V nginx
package-cleanup --verify

# Trace dependency resolution
dnf debuginfo-install package
dnf debug-dump
dnf debug-restore dump.txt

Best Practices

Repository Management Strategy

Use official repositories when possible
Verify third-party repository trustworthiness
Implement repository priorities
Maintain local mirrors for critical environments
Regular repository metadata updates

Security Considerations

# Security audit script
#!/bin/bash

echo "=== Package Security Audit ==="

# Check for security updates
updates=$(dnf updateinfo list security | grep -c "Security")
echo "Security updates available: $updates"

# Verify GPG keys
echo "Installed GPG keys:"
rpm -qa gpg-pubkey* --qf "%{name}-%{version}-%{release} %{summary}\n"

# Check package signatures
echo "Checking package signatures..."
rpm -qa --qf '%{name}-%{version}-%{release} %{SIGPGP:pgpsig}\n' | grep -v "Key ID"

# List packages from unknown vendors
echo "Packages from unknown vendors:"
rpm -qa --qf '%{name} %{vendor}\n' | grep -v "CentOS\|Red Hat"

Conclusion

YUM and DNF provide comprehensive package management capabilities for CentOS/RHEL systems. Master these tools to efficiently manage software, maintain system security, and automate package operations in enterprise environments.

YUM/DNF Package Management: Advanced Software Management in CentOS/RHEL

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YUM/DNF Package Management: Advanced Software Management in CentOS/RHEL

Package Management Fundamentals

Basic DNF/YUM Commands

Package Installation and Removal

Repository Management

Configure YUM/DNF Repositories

EPEL and Third-Party Repositories

Package Groups and Modules

Group Management

Module Streams (AppStream)

Advanced Package Operations

Package Dependencies

Transaction History

Package Caching and Performance

Cache Management

Performance Optimization

Security and Package Verification

GPG Key Management

Security Updates

Creating and Managing Local Repositories

Create Local Repository

Mirror Remote Repositories

Package Building and RPM Management

Query RPM Packages

Build Custom RPMs

Automation and Scripting

DNF Automatic Updates

Scripting Package Management

Troubleshooting

Common Issues

Debug Package Issues

Best Practices

Repository Management Strategy

Security Considerations

Conclusion