Install Nextcloud with Docker on Debian 10 Buster

nextcloud docker installation on debian buster
Nextcloud is a lightweight, open-source StaaS (Storage as a Service) platform, written i PHP and JavaScript, which provides file sync, file sharing and creative collaboration services. The software can be installed on local hardware as a perfect alternative for commercial StaaS solutions like Dropbox, OneDrive, Hightail, etc…
Nextcloud is a typical LAMP (Linux Apache MySQL PHP) software, but instead of ardous and problematic LAMP environment installation and file sharing platform implementation, we can deploy a turnkey Nextcloud platform in just a few minutes, using Docker containers, preferably with docker-compose.

In this article I am launching Nextcloud platform in two Docker containers: nextcloud and mariadb which use local Docker volumes as a file and database storage. This solution will enable us to quickly and painlessly upgrade our Nextcloud to a newer versions in future.
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Enable UEFI for QEMU KVM on Fedora

Enable UEFI for QEMU KVM on Fedora
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.
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How to configure Docker Proxy on CentOS 7, RHEL 7

How to enable Proxy for Docker engine with or without authentication on CentOS 7, Red Hat Enterprise Linux 7?

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OpenStack Pike VLAN and Flat network based installation using Packstack

OpenStack Pike VLAN and Flat network based Installation using Packstack
In previous articles regarding OpenStack RDO installations we presented OpenStack deployments using Packstack automated installer script, which still required some post-installation networking configuration to be performed in order to accomplish whole deployment. This time we will try to prepare Packstack configuration file (answers.txt) in such way, that it does all the magic and no post-installation configuration is required. We will make full bridge:interface mapping so, that no further bridge setup is needed and the environment should be ready to use immediately after Packstack deployment.
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How to find qbr,qvo interfaces of the particular Instance in OpenStack

locate qbr,qvo interfaces of the particular Instance in OpenStack
OpenStack networking topology is pretty complicated structure, even with it’s, let’s say, default configuration based on OVS (OpenVSwitch), not even mentioning about additional overlays, like OpenDaylight or Nuage.
If you are troubleshooting network issues in regard to a particular Instance (VM), it’s good to locate network overlay interfaces (qbr, qvo) assigned to that Instance to have a starting point to begin your network analysis from. You can then analyze inbound/outbound traffic on those interfaces using network protocol analyzers, like tcpdump/wireshark.

Below you can find few steps, how to locate qbr,qvo interfaces belonging to a particular Instance:
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How to Install VirtualBox 5.1 on Fedora 23 from RPMs

install virtualbox 5.1 on fedora 23
Oracle VM VirtualBox is a flexible open-source hypervisor for x86 computers from Oracle Corporation initially developed by Innotek GmbH. It runs on many platforms including: Linux, Windows, Solaris, providing great virtualization environment to run multiple VMs at a time.

In this tutorial we present how to install VirtualBox 5.1 on Fedora 23 from RPMs in few simple steps.
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Install and Configure KVM (Bridge Net Interface) on CentOS 7 / RHEL 7

kvm installation configuration setup on centos7 redhat7
KVM (Kernel-based Virtual Machine) is a virtualization infrastructure for the Linux which requires a processor with hardware virtualization extension to be able to host guest sytems. KVM is convenient solution to test and try different operating systems if you don’t have a possibility to purchase expensive and power consuming physical hardware.

The below tutorial presents KVM (QEMU) installation and setup along with Linux Bridge configuration on CentOS7 / RedHat7 operating system.
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How to shrink OpenStack qcow2 image using qemu-img

shrink openstack qcow2 image
If you transfer qcow2 images very frequently across OpenStack Clouds or between KVM and Openstack environments, they can quickly grow larger. Luckily qcow2 image size can be decreased to reasonable values using qemu-img tool. Below we present how to shrink Openstack/KVM qcow2 image.
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virt-what: Check if your remote server runs in virtual environment

virt-what - detect if we are running in a virtual machine
Have you ever wondered if the server you bought at the hosting provider is in fact a dedicated server or just a VPS and what is the underlying virtualization environment your server runs on?
virt-what provides us the ability to detect if we are running in a virtual machine or on bare-metal (real hrdware). virt-what detects common types of virtualization: hyperv, kvm, openvz, qemu, virtualbox, vmware, xen, etc…
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