Red Hat Packages
1. RPM Packaging Basics
Red Hat systems use the RPM Package Manager (RPM) to handle software distribution, ensuring consistency, ease of installation, and maintenance.
Key Components of an RPM Package
1. Metadata:
Information about the package (e.g., name, version, release, license).
2. Compiled Binaries:
Executables and libraries required for the software to function.
3. Configuration Files:
Default settings, typically stored in /etc.
4. Scripts:
Pre- and post-install/uninstall scripts for setup and cleanup tasks.
2. The Spec File
The spec file, located in ~/rpmbuild/SPECS, defines how an RPM package is built and what it contains. It is the blueprint of the package.
Key Sections of a Spec File
1. Header
Contains metadata such as package name, version, and license.
2. Build Requirements
Specifies dependencies needed during the build process (e.g., BuildRequires: gcc).
3. Source and Patch Definitions
Points to source tarballs and patch files.
4. Build Instructions
Includes build steps, typically using make or similar tools.
5. File List
Defines the files and directories included in the package.
6. Changelog
Tracks changes made to the package over time.
3. Basic RPM Commands
Managing RPM Packages
Install a Package
sudo rpm -ivh package.rpm
Upgrade a Package
sudo rpm -Uvh package.rpm
Query Installed Packages
rpm -q package-name
Verify a Package
rpm -V package-name
Remove a Package
sudo rpm -e package-name
Building RPM from source
rpmbuild -ba ~/rpmbuild/SPECS/package.spec
4. YUM and DNF Package Managers
YUM and DNF are tools built on top of RPM to handle package management with automatic dependency resolution.
Install a Package
sudo dnf install package-name
Remove a Package
sudo dnf remove package-name
Update all Packages
sudo dnf update
Search for a package
dnf search package-name
List installed Package
dnf list installed
5. Patching RPM Packages
Patching involves modifying a package to fix vulnerabilities, add customizations, or remove branding. It ensures packages meet specific security or functional requirements. Patching Workflow
1. Extract the Source RPM
pmbuild --rebuild package.src.rpm
2. Apply the Patch
Patch1: my-patch.patch
Apply the patch during the build process
%prep
%setup -q
%patch1 -p1
3. Build the Patched Package
rpmbuild -ba ~/rpmbuild/SPECS/package.spec
4. Verify the Package (Check Integrity)
rpm -K package.rpm
6. Golden Images
A golden image is a pre-configured template system image used for deploying systems quickly and consistently.
Golden Image Best Practices
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Start with a Minimal Base
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Apply Customizations
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Include Patches
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Regular Updates
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Validation