Category: Linux

Bash, Linux

Install and Configure Checkmk on CentOS 8 and Monitor Linux Hosts using Checkmk agent

Jan 18, 2020 by Grzegorz Juszczak 1 Comments , , , , , , , ,


If you have important production servers or critical services in your network, having monitoring tools becomes a must. In case of any hardware or software failures, it is crucial to get alerted as soon as possible and take appropriate actions to fix the failure.
In this article I would like to take a look at checkmk – a powerful monitoring software, developed by tribe29 GmbH with tons of configuration options and a user-friendly WebGUI, which can help you fully automate monitoring activities of your hardware and operating systems.
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Bash, Linux

Configure Postfix SMTP Relay (Smart Host) on CentOS 8

Jan 17, 2020 by Grzegorz Juszczak 2 Comments , , , , , , , ,

Install and Configure Postfix SMTP Smart Host on CentOS
Postfix is a Mail Transport Agent (MTA), which can be easily configured as a private relay host, passing mail to other mail servers. Unlike Sendmail, Postfix is considered a very secure MTA, offering a high level of flexibility and ease of administration.
In this article, I am configuring Postfix on CentOS 8, running on CinderCloud VPS, as SMTP smart host (relay host) using SASL authentication to send out mail further to the OVH mail server.
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Bash, Linux

Configure Sendmail MTA on CentOS 8 to work as SMTP Relay

Jan 5, 2020 by Grzegorz Juszczak 2 Comments , , , , , , , ,


Sendmail is easy to implement, lightweight electronic Mail Transport Agent (MTA), which enables you to automate the process of sending e-mail messages from your Linux host. It can play a significant role as a background mechanism for processing outbound emails from monitoring software to deliver status notifications to the system administrators or send diagnostic information at a specified time schedule.
In this article, I present how to install and configure Sendmail on CentOS 8 to work as SMTP Relay for outbound traffic to the OVH mail server.
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Linux

High Availability Apache Galera Cluster with HAProxy Load Balancer

May 5, 2019 by Grzegorz Juszczak 4 Comments , , , , , , , , ,


Using a high-availability LAMP (Linux Apache MySQL/MariaDB PHP) server may totally eliminate the risk of server’s downtime, which can be crucial in case of a production HTTP server, serving critical business application. We can set a redundant, fully functional, high-avalability production HTTP server for free, using well known and proven technologies like Apache server, MariaDB/Galera cluster software and HAProxy load balancer.
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Linux, Storage, Virtualization

Install Nextcloud with Docker on Debian 10 Buster

Apr 23, 2019 by Grzegorz Juszczak 14 Comments , , , , , , , ,

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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Cloud Computing, Linux

OpenStack Pike TripleO Overcloud Deployment using VLAN based Network Isolation

Feb 10, 2019 by Grzegorz Juszczak 9 Comments , , , , , , , ,

OpenStack Pike TripleO Overcloud Deployment with Network Isolation
The basic OpenStack TripleO deployment utilises the so called provisioning / control plane network for all types of traffic (internal API, tenant, storage, storage management, etc…), that run across the whole OpenStack installation. The Undercloud node, which is used for Overcloud deployment, becomes a kind of a gateway for Overcloud nodes to the external network. This solution has a major disadventage: the single point of access which is here the Undercloud node, can quickly turn into a single point of failure, if Undercloud fails, cutting us out from Overcloud nodes. Moreover, any diagnostic steps, in case of network issues, bottle necks, etc., become more difficult , since all the traffic runs in one big tube, which is provisioning / control plane network.
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Bash, Linux

Kickstart Tutorial – Practical Examples for RHEL 7 / CentOS 7

Feb 2, 2019 by Grzegorz Juszczak 7 Comments , , , , , , , , ,

kickstart tutorial Red Hat 7 CentOS 7
Linux installation can be performed totally unattended using Kickstart file, which contains configuration, required setup and post installation tasks to fully automate installation process without being prompted for any input details. Kickstart file can be placed in the remote repository or can be included in ISO image in order to be read by Anaconda installer during system installation.

In this tutorial we present some practical solutions that can be placed in kickstart file to automate CentOS 7 / Red Hat 7 installation tasks.
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Cloud Computing, Linux

Extending Minimum Time Between IPMI Operations in OpenStack Ironic

Sep 29, 2018 by Grzegorz Juszczak 0 Comments , , , , , , , ,

Extending Minimum Time Between IPMI Operations in OpenStack Ironic
In TripleO based installations of OpenStack the deployment of Overcloud nodes is coordinated by so called Ironic module, which was developed in general to deploy OS on bare metal servers. There is a number of IPMI (Intelligent Platform Management Interface) drivers supported by Ironic, like pxe_ilo for HP Proliant Gen8+, pxe_drac for DELL 12G+, ipmi for generic servers, etc… In case of the generic ipmi driver, Ironic script, which is installed on undercloud (or OSP director), uses a Linux command line ipmitool to send IPMI messages to the Overcloud nodes to control them during TripleO deployment.
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Cloud Computing, Linux

OpenStack Pike TripleO Undercloud and Overcloud Deployment on 3 Bare Metal Servers

Jul 18, 2018 by Grzegorz Juszczak 3 Comments , , , , , , , , ,

OpenStack Pike TripleO Undercloud and Overcloud Deployment on Bare Metal
Nowadays Packstack based OpenStack installations are used for proof-of-concept and demonstration purposes only. The official RDO community points TripleO (OpenStack On OpenStack) as a recommended OpenStack deployment method for production cloud. TripleO is an automated installation tool, based on Ironic OpenStack node provisioning software, intended for deployments on bare metal servers, that is, on physical hardware. TripleO generally requires using servers equipped with BMC (Baseboard Management Controller) or IPMI (Intelligent Platform Management Interface) modules, like HPE iLO (integrated Lights Out) in order to be able to manage and controll servers during OpenStack deployment, maintenance and node introspection procedures.
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Linux, Virtualization

Enable UEFI for QEMU KVM on Fedora

May 31, 2018 by Grzegorz Juszczak 0 Comments , , , , , , , , ,

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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