UEFI (Unified Extensible Firmware Interface) has become a successfull successor of an outworn and obsolete BIOS firmware. Emulating UEFI based hardware on KVM/QEMU Virtual Machine is possible thanks to so called OVMF (Open Virtual Machine Firmware), which comes from EDK2 (EFI Development Kit), UEFI reference implementation. OVMF is available as an RPM package for RPM based distros (CentOS, Fedora, Red Hat). In case of Fedora release all we need is edk2-ovmf RPM package.
Continue reading “Enable UEFI for QEMU KVM on Fedora”
How to enable Proxy for Docker engine with or without authentication on CentOS 7, Red Hat Enterprise Linux 7?
CentOS 7 may offer us a possibility of automatic RAID configuration in Anaconda installer, that is during OS installation, once it detects more than one physical device attached to the computer. Mentioned RAID is generally the LVM-RAID setup, based on well known mdadm – Linux Software RAID. It’s a pretty convenient solution, since we don’t need to setup RAID manually after installation, on already running system.
The below procedure presents CentOS 7 testing installation with LVM RAID 1 (Mirroring) on KVM based Virtual Machine with two attached 20GB virtual disks.
Continue reading “CentOS 7 Installation with LVM RAID 1 – Mirroring”
Testing OpenStack Pike after Packstack based deployment I realised MySQL daemon was utilizing 100% CPU resources without any specific reason, but I had never faced such problem before in previous OpenStack releases. The problem also has never appeared during my TripleO based OpenStack Pike deployments, so looks like it’s strictly Packstack related issue.
The situation heppened on few bare metal installations on pretty powerful servers. Restarting mariadb service was helpful just for the first few minutes after service restart, then the problem would happen again and again, what resulted in frequent Horizon Dashboard and Keystone inaccessibility and partial Controller unavailability.
Continue reading “MariaDB high CPU usage in OpenStack Pike”
Heat is an OpenStack Orchestration service, which implements an orchestration engine to launch multiple composite cloud applications based on templates in the form of text files that can be treated like code. Heat service is able to read YAML (.yaml, .yml) files and perform different tasks inside OpenStack environment included in YAML components. Using Heat Orchestration we can create instances, networks or even whole tenants with just single mouse click in OpenStack dashboard (Horizon), if we have previously prepared YAML file with Heat instructions to be performed in OpenStack cloud.
In this tutorial we will create example .yaml file for Heat orchestration containing instructions and components needed to deploy project tenant in OpenStack and launch instances inside the tenant. Next, we will create our stack on single OpenStack all-in-one node based on CentOS 7.3 operating system.
Continue reading “Deploy project tenant in OpenStack using Heat orchestration stack”
DNF is a next generation package manager for RPM-based Linux distributions, commonly used in newest Fedora releases. DNF is a Yum succesor, which provides Yum backward compatibility, but one of aspects, which make DNF a powerful package manager is the ability to manage transaction history.
Using DNF, we can easily undo or redo RPM package upgrade, installation and removal. This gives us the opportunity to rollback the system, if we feel, that our recent RPM package operations disordered the system.
Below we presents, how to work with DNF transaction history on Fedora 24.
Continue reading “Fedora DNF rollback RPM package update, removal, installation”
WebDAV (Web Distributed Authoring and Versioning) is an extension of the Hypertext Transfer Protocol (HTTP) that allows clients to perform remote Web content authoring operations. The WebDAV protocol provides a framework for users to create, change, copy, move, lock and version the files on a server, typically a web server or web share. This type of protocol is used by some hosting providers (like my favorite HostUpon) in cPanel software, to provide quick and easy access to the files stored in hosting account disk space.
In this tutorial we are mounting remote WebDAV resource in Fedora release 24 via davfs2 file system driver.
Continue reading “Mount WebDAV remote storage in Fedora Linux using davfs2 driver”
Jenkins is a popular and open source automation server written in Java, which helps automate the non-human part of the whole software development process. Jenkins supports BASH shell scripts, can be integrated with version control systems and it’s builds can be scheduled via a cron-like mechanism.
In this tutorial we are installing Jenkins stable version from RPM package via Jenkins dedicated repository using DNF package manager.
Continue reading “Install Jenkins on Fedora 23 from RPM via DNF package manager”
Ansible is a simple open-source automation tool that can automate cloud deployment, application deployment or Linux OS maintenance. Comparing Ansible to other automation tools (i.e. Puppet), it’s the simplest tool, because it’s agentless. Ansible once installed on a control node, connects to a managed node via SSH, which doesn’t require any client applications installed on that node.
Installation of Ansible on Fedora based control node is pretty simple and straightforward, since it can be installed from RPM packages. In this tutorial we are installing Ansible on Fedora 23 via dnf package manager.
Continue reading “Install Ansible on Fedora via DNF from RPM packages”
GRUB2 Linux Boot Loader provides few customization options, that can transform it into an attention drawing eye candy. It’s main feature is the possibility to customize the splash screen being displayed with GRUB 2 menu entries upon system boot. This feature can be used not only in GRUB2 installed on hard disk for already installed operating systems, but also in GRUB2 Boot Loader placed on ISO image when booting from ISO/CD/DVD. This is pretty useful as well, when we want to create customized ISO image with the company logo based on some Linux Distro, which provides a company product.
In this tutorial we present how to create:
- GRUB2 custom splash screen on RHEL 7 / CentOS 7 ISO image for UEFI Boot
- GRUB2 custom splash screen on RHEL 7 / CentOS 7 ISO image for Legacy BIOS Boot