In a Linux HA cluster setup on RHEL 6 that involves replication between sites using DRBD suddenly after reboot of one of the nodes it was imposible to start any cluster service from that node. Surprinsingly there was no issue to do so from the other node. While looking in the /var/log/messages on the affected… Read More »
I started from a great post Monitoring your Ubiquiti home-network with a Docker LibreNMS and SNMP, to make my own network monitor where to gather all the network devices SNMP messages. Because I like docker compose files to start up all my components and I want to use a separate docker mysql I made the… Read More »
In the following I am trying to create a Jboss EAP docker image with up-to-date patches and configurations applied using JBoss CLI. With this template I can then very easy setup any complex JBoss based application environment with ready defined data sources, connectors , resource adapters etc. In the following I will describe the steps… Read More »
Everybody that works with big vendor databases like Oracle or DB2 knows that when you have a lot of data and the database is initializing or recovering after a disaster there are dead times when the database isin a state of limbo. It is started but still not in usable state. Usually the enterprise applications… Read More »
Sometimes weird things happen when selinux is activated and files are un-tagged or policies are missing. Because I do not want to apply the usual stupid Internet advice: “disable selinux” I am trying to fix it if possible. Two simple steps to alleviate some of the “issues” caused by selinux. STEP 1: Generate SELinux policy… Read More »
This tutorial is part of the effort to deploy a complex business application on a docker swarm and is focused on deploying a swarm accessible secured private registry using letsencrypt certificates. The first step is to create the swarm, see Create and manage a Docker Swarm with Docker CE and register it to Docker Cloud… Read More »
After your environment grows and you add more and more servers at some point the need to have a simple visual monitoring of everything becomes vital. If you throw into this environment a container environment like docker than you have to monitor even more information. After creating a docker swarm see Create and manage a… Read More »
How to execute an arbitrary command on any docker container running in a docker swarm ? There is no way of directly executing a ‘docker exec’ on a container in the swarm. On a swarm we can define stack of services and directly only services are visible. The containers that run the actual service and… Read More »
The new Docker CE makes it easy to deploy and work with Docker Swarm. I will describe how to setup a test 4 node Docker Swarm that will be further used to host a test enterprise application (a post is going to follow with that). STEP 1: First some practical considerations A Docker Swarm is… Read More »
There is a new Docker version released in march see Docker: New Docker release. There are some important changes, but the cool ones are in the experimental mode: – you no longer need docker-machine for lots of stuff – a new way to create Docker swarms – a new docker-compose, version 3 that supports automatic… Read More »