Category Archives: Databases

A NoSQL database provides a mechanism for storage and retrieval of data that is modeled in means other than the tabular relations used in relational databases.
A relational database management system is a database management system based on the relational model of data.

Elastic Stack: an overview and ELK installation on Ubuntu 20.04

22 February 2022

 The last time I’ve worked with the ELK stack about 7 years ago, see the ELK: установка Elasticsearch+Logstash+Kibana на CentOS. Currently, we are using, but its costs going higher and higher, so we started looking at the self-hosted ELK solution to be running on our AWS Elastic Kubernetes Service clusters. So, the task, for… Read More »

Tableau: install Tableau Bridge to access a database server in a private network

9 August 2021

 To access a database server, that has no public access (as it must be – access only inside an AWS VPC), Tableau suggests using its tool called Tableau Bridge. The idea is to have a Bridge service running in a network, which has access to a database server via its Private IP. Also, Bridge will… Read More »

Linux: LEMP set up – NGINX, PHP, MySQL, SSL, monitoring, logs, and a WordPress blog migration

6 November 2020

 Finally got time to migrate the RTFM.CO.UA blog to a new server with Debian 10. This time manually, without any automation will set up a LEMP stack Wrote a similar at 2016 – Debian: установка LEMP — NGINX + PHP-FPM + MariaDB (Rus), but in time the post is more complete of the process and… Read More »

Jenkins: Redis deployment, and Helm subchart values

1 November 2020

 The task is to create a Jenkins job to deploy Redis to Dev/Stage/Prod Kubernetes clusters. In the Redis: running Master-Slave replication in Kubernetes we did it manually to see how it’s working, now it’s time to automate it. The main question is how to pass parameters for different environments during the deployment? I’d like to… Read More »

Kubernetes: running SQL migrations with Kubernetes Job and Helm hook

27 October 2020

 We have a project running in Kubernetes that needs to run SQL migrations during deployment. To run migrations need to clone a Github repository and run actually migrations stored in it. Currently, this is done with Kubernetes initContainers , and there are two of them – the first one with git clones the repository with… Read More »

Redis: running Master-Slave replication in Kubernetes

29 September 2020

 The task is to spin up a Redis instance in a Kubernetes cluster. Will use the Master-Slave replication setup with Sentinels for monitoring and failover operations. Check the Redis: replication, part 2 – Master-Slave replication, and Redis Sentinel post for more details. Redis cluster vs Redis replication See Redis: replication, part 1 – an overview.… Read More »

AWS Elastic Kubernetes Service: load-testing and high-load tuning – problems and solutions

4 September 2020

 Actually, this post was planned as a short note about using NodeAffinity for Kubernetes Pod: But then, as often happens, after starting writing about one thing, I faced another, and then another one, and as a result – I made this long-read post about Kubernetes load-testing. So, I’ve started about NodeAffinity, but then wondered how… Read More »

Redis: “psync scheduled to be closed ASAP for overcoming of output buffer limits” and the client-output-buffer-limit

26 February 2020

 We have a Redis-cluster with Master-slave replication and Sentinel, see the Redis: replication, part 2 – Master-Slave replication, and Redis Sentinel, Redis: fork – Cannot allocate memory, Linux, virtual memory and vm.overcommit_memory, and Redis: main configuration parameters and performance tuning overview posts. The system worked great until we started using it much more actively. Redis… Read More »