When most people deploy an Open vSwitch configuration for virtual networking using the NORMAL rule, that is, using L2 learning, they do not think about configuring the size of the Forwarding DataBase (FDB).
When hardware-based switches are used, the FDB size is generally rather large and the large FDB size is a key selling point. However for Open vSwitch, the default FDB value is rather small, for example, in version 2.9 and earlier it is only 2K entries. Starting with version 2.10 the FDB size was increased to 8K entries. Note that for Open vSwitch, each bridge has its own FDB table for which the size is individually configurable.
This blog explains the effects of configuring too small an FDB table, how to identify which bridge is suffering from too small an FDB table, and how to configure the FDB table size appropriately.
Continue reading “Troubleshooting FDB table wrapping in Open vSwitch”
This article describes how to configure MongoDB’s WiredTiger memory cache in Red Hat Mobile Application Platform (RHMAP) to prevent high-usage memory issues and Nagios alerts. If the WiredTiger cache consumes all the memory available for a container, memory issues and Nagios alerts will occur.
The WiredTiger storage engine is the default storage engine starting in MongoDB version 3.2. It uses MultiVersion Concurrency Control (MVCC) architecture for write operations in order to allow multiple different modifications to the same document at the same time.
WiredTiger also caches data and creates checkpoints to give you the ability to recover anytime it’s necessary. For example, if a MongoDB image deployed in a container fails, it is useful to recover the data that was not persisted. Additionally, WiredTiger can recover un-checkpointed data with its journal files. See the journal documentation and snapshots and checkpoint documentation for more information.
Continue reading “Configuring the MongoDB WiredTiger memory cache for RHMAP”
The Red Hat Training team is very pleased to announce the release of our latest video classroom course, Red Hat Application Development I: Programming Java EE (JB183). JB183 is the preparatory course for the Red Hat Certified Enterprise Application Developer Exam (EX183). This video classroom course is available now as part of the Red Hat Learning Subscription or as a separate a la carte purchase.
In this course, veteran instructor Will Dinyes guides you through enterprise Java development with easy-to-follow lectures and demonstrations. JB183 is designed for students with a strong understanding of Java SE and object-oriented programming who want to learn how to begin developing modern enterprise applications on Red Hat JBoss Enterprise Application Platform (JBoss EAP) 7.0.
Continue reading “Red Hat Application Development I: Programming Java EE (JB183) course now available”
This post is a short summary of my recent experiences with customers that are implementing architectures similar to microservices but with different characteristics in the current post-microservices world.
The microservices architectural style has been around for close to five years now, and much has been said and written about it. Today, I see teams deciding not to strictly follow certain principles of the “pure” microservices architecture and to break some of the “rules.” Teams are now more informed about the pros and cons of microservices, and they make context-driven decisions respecting team experience and organizational boundaries and accept the fact that not every company is Netflix. Below are some examples I have seen in my recent microservices gigs.
Continue reading “The rise of non-microservices architectures”
This is the first in a series of articles that consider the role of Kubernetes and application servers. Do application servers need to exist? Where does the current situation leave developers trying to choose the right path forward for their applications?
Why Kubernetes is the new application server
By now you’ve likely read “Why Kubernetes is The New Application Server” and you might be wondering what that means for you. How does it impact Java EE or Jakarta EE and Eclipse MicroProfile? What about application servers or fat JARs? Is it the end as we’ve known it for nearly two decades?
In reality, it doesn’t impact the worldview for most. It’s in line with the efforts of a majority of vendors around Docker and Kubernetes deployments over the last few years. In addition, there’s greater interest in service mesh infrastructures, such as Istio, and how they can further assist with managing Kubernetes deployments.
Continue reading “Kubernetes is the new application operating environment (Part 1)”
For those unfamiliar, Open Virtual Network (OVN) is a subproject of OpenVswitch (OVS), a performant programmable multi-platform virtual switch. OVN provides the ability to express an overlay network as a series of virtual routers and switches. OVN also provides native methods for setting up Access Control Lists (ACLs), and it functions as an OpenFlow switch, providing services such as DHCP. The components of OVN program OVS on each of the hypervisors in the network. Many of Red Hat’s products, such as Red Hat OpenStack Platform and Red Hat Virtualization, are now using OVN. Red Hat OpenShift Container Platform will be using OVN soon.
Looking around the internet, it’s pretty easy to find high-quality tutorials on the basics of OVN. However, when it comes to more-advanced topics, it sometimes feels like the amount of information is lacking. In this tutorial, we’ll examine dynamic addressing in OVN. You will learn about IP address management (IPAM) options in OVN and how to apply them.
Continue reading “Dynamic IP Address Management in Open Virtual Network (OVN): Part One”
Red Hat Enterprise Linux (RHEL) 7.6 Beta was released a few days ago and one of the first new features I noticed is Podman. Podman complements Buildah and Skopeo by offering an experience similar to the Docker command line: allowing users to run standalone (non-orchestrated) containers. And Podman doesn’t require a daemon to run containers and pods, so we can easily say goodbye to big fat daemons.
Podman implements almost all the Docker CLI commands (apart from the ones related to Docker Swarm, of course). For container orchestration, I suggest you take a look at Kubernetes and Red Hat OpenShift.
Podman consists of just a single command to run on the command line. There are no daemons in the background doing stuff, and this means that Podman can be integrated into system services through
We’ll cover some real examples that show how easy it can be to transition from the Docker CLI to Podman.
Continue reading “Intro to Podman (Red Hat Enterprise Linux 7.6 Beta)”
Securing applications and services is no longer just about assigning a username and password. You need to manage identities. You need to integrate with legacy and external authentication systems to provide features that are in demand like social logins and single sign-on (SSO). Your list of other requirements may be long. But you don’t want to develop all of this yourself, nor should you.
Continue reading “Securing apps and services with Keycloak (Watch DevNation Live video)”
With the release of Apache Camel 2.21, some new components were added to the project and Camel WordPress was one of them. Camel is one of the upstream community projects for Red Hat Fuse. In this article, we will see how to use this new component to publish an auto-generated news post based on a soccer statistics API. The example consumes the statistics API, generates the text based on a Natural Language Generation (NLG) library and then publishes it to the WordPress blog.
WordPress is one of the most used open source tools for creating websites. More than 30% of the web is built on top of WordPress. Besides creating websites, blogs, and apps, WordPress leverages a huge plugin repository maintained by a passionate community. There are even plugins that can turn a WordPress website into an e-commerce platform.
Since version 4.7, WordPress exposes a REST API capable of interacting with its resources, for example, users, categories, pages, posts, and custom types. Now it’s possible for third parties to integrate with the WordPress platform and perform almost anything with their resources.
Some companies implement internal websites, blogs, and project sites using WordPress. Integrating such platforms with another company’s components—such as CRM, ERP, LDAP, and Calendar Services—would add extra value to WordPress-based projects. Camel WordPress can help integrate those components easily. To get started using this new component, nothing is better than a demo.
Continue reading “Auto-generating news and publishing it to WordPress with Apache Camel”