Blog Grid

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

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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Configure Postfix SMTP Relay (Smart Host) on CentOS 8

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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Configure Sendmail MTA on CentOS 8 to work as SMTP Relay

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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High Availability Apache Galera Cluster with HAProxy Load Balancer

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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Install Nextcloud with Docker on Debian 10 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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OpenStack Pike TripleO Overcloud Deployment using VLAN based 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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