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Tanzu Developer Blog

Declarative Deployments in Kubernetes: What Options Do I Have?
Dan Dobrin July 30, 2020

Your cloud-native application has been designed, built, and tested locally, and now you’re taking the next step: deployment to Kubernetes.

Isolated environments can be provisioned as namespaces in a self-service manner with minimal human intervention through the Kubernetes scheduler. However, as the number of microservices increases, continually updating and replacing applications with newer versions, along with observing and monitoring the success/failure of deployments, becomes an increasing burden.

Deployment processes are performed while allowing for zero or some downtime, at the expense of increased resource consumption or support of concurrent app versions.

What options do you have to turn deployments into a predictable, repeatable, consistent, easy to observe process? Kubernetes with declarative deployments.

What Are Declarative Deployments in Kubernetes?

The concept of deployment in Kubernetes encapsulates the upgrade and rollback processes of a group of containers and makes its execution a repeatable and automated activity.

The declarative nature of a Kubernetes deployment allows you to specify how the deployed state should look, rather than the steps to get there. Declarative deployments allow us to describe how an application should be updated, leveraging different strategies while allowing for fine-tuning of the various aspects of the deployment process.

The …

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What’s New in .NET Core for Containers and Microservices
Santiago Vasquez July 22, 2020

Throughout most of my career as a developer, I have written code using .NET (mostly C#). But lately, I have been spending more time with Spring, and I keep hearing comments about exciting changes in .NET around containers. I decided it was time to go back and check out what I had missed. This article highlights some of these changes, emphasizing the ones most relevant to containers and microservices; after all, I am part of the VMware Tanzu Portfolio.

Microsoft released .NET Core 3.0 on Sept. 23, 2019, and a couple of months later, on Dec. 3, 2019, version 3.1 followed. Version 3.0 had already reached its end of life, while version 3.1, with its LTS designation, will have support until Dec. 3, 2022 (more details here).

.NET Core 3.1 contains a tiny number of changes compared to version 3.0. These are mainly related to Blazor and Windows Desktop, in addition to the LTS designation. The bulk of significant changes were in version 3.0. I have selected a subset of items that I believe have a more significant impact on my day-to-day role at VMware Pivotal Labs. For the complete list of changes, go here and here.

From Container-Friendly to Container-Aware

Before version 3, running .NET Core in a container was not for the faint of heart. CoreCLR was inefficient when allocating GC heaps and quickly ran into Out-of-Memory situations. The new version of .NET Core has made significant …

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Kubernetes at Home: Local k8s Options
Brian McClain July 17, 2020

When you’re first learning how Kubernetes works, or are developing code that leverages Kubernetes, you’re likely to find yourself looking to one of the many options available to run it locally. As with almost anything in technology, there are more options than you probably know what to do with, which can leave you asking yourself which one you should use. Minikube? Kind? Microk8s? Even Docker Desktop ships with the ability to spin up Kubernetes.

Consider a scenario in which you need to develop and test on Kubernetes locally. For example, Spring Cloud Kubernetes gives you tools such as service discovery, which enables you to look up Kubernetes services, as well as the ability to set properties in your code using ConfigurationMaps. This post will use a simple two-tier application that has a frontend (written in Spring) that looks up where the backend service is (also written in Spring) by looking up the service name that exposes it. The backend service presents a REST API that reports inventory information about an imaginary grocery store, and the frontend application visualizes it.

Since the whole point is to develop locally, you’ll deploy the backend, then get a shell into another pod that mounts a volume from your local machine containing the frontend code. This will allow you to rapidly iterate changes to the code without building and deploying a new container every time. …

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Save Your Stack: Build Cloud Native Apps with Spring, Kubernetes and Cassandra
Chris Splinter July 8, 2020

You can start to build modern, cloud native apps today using the latest innovations from Spring, Cassandra and Kubernetes. This blog will show you code samples and a fully working demo to get you up to speed in minutes with these open-source technologies.


There’s no shortage of buzzwords, such as “digital transformation”, “cloud native” and “serverless,” being thrown around the internet. Peeling back a layer of the buzzword onion, we do see significant changes in the technology world that have inspired these terms. First, most companies are becoming technology companies as having a presence in the digital space grows as a requirement for survival. Second, the mad dash to the cloud is showing no signs of slowing down. Third, time to market for new applications matters more than ever.

So, how has this affected technology practitioners? Well, the developer population is multiplying rapidly and the pressures for faster delivery of these new digital experiences are getting more extreme by the day. It’s now a fundamental expectation that applications will be there whenever, wherever and however users want to engage. The cloud movement is creating complex architectures that span on-premises and cloud environments, not to mention the pure amount of data coming through these services is exploding. Sounds fun!

Open-source technology …

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A Container Is a Linux Namespace and Networking Basics
Ivan Tarin June 29, 2020

open source image @freddygthatsme see sources

Understanding the way containers communicate will make your life easier in many ways. Technologies like Kubernetes and Docker abstract away details that make containers special, but can also abstract away intuition and understanding. Without that knowledge, challenges arise—educated problem-solving adds confidence to decision-making!

In this post, we will demystify containers and cover some networking basics by explaining how to create two rudimentary containers and connecting them with a virtual network so they can talk to each other. The host machine, which is the machine where the network lives, views this network as if it were completely external. So, we will connect the network to the host. We’ve also included a bonus section about connecting the network to the internet so your containers can reach Google. You do not need a Linux machine to run through the exercises.

Containers and Networks: What Are They?

A container can be considered synonymous with a Linux network namespace. Keep this in mind. Essentially, a container is a namespace.

Each container runtime uses a namespace differently. For example, containers in Docker get their own namespace, while in CoreOS’ rkt, groups of containers share namespaces, each of which is …

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Git Switch and Restore: an Improved User Experience
Ray Chuan Tay June 23, 2020

If you’re like me and you’ve worked with Git for some time, you might have a couple of commands committed to your memory—from git commit for recording your changes, to git log for sensing “where” you are.

I have found git checkout to be a command that I reach for pretty frequently, as it performs more than one operation. But a single command doing more than one thing might produce a suboptimal user experience for someone learning Git. I can almost picture an XKCD strip:

Learner: What do I run to change the branch I’m on?
You: Use git checkout <branch>.
Learner: What can I run to discard changes to a file?
You: Use…git checkout <file>.
Learner: OK…

Even if you have the commands memorized, there have likely been times when you had to pause after typing a git checkout command while you tried to match it with the operation you had in mind (e.g., “I just typed git checkout … to do X, but I thought git checkout does Y, does this really do what I want?")

Let’s take a look at what git checkout can do, and an alternative (or two) that can make for a friendlier user experience in Git.

Quick, what does git checkout do?

Perhaps you were trying something out and made some changes to the files in your local Git repository, and you now want to discard those changes. You can do so by calling git checkout with one …

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From Commit to Container
Tyler Britten May 29, 2020

While running software in containers is very popular, it can be a little confusing to figure out the best way to get your code into a container. Now that the industry is mostly unified on Open Container Initiative (OCI) Standard container image formats, they can be built in any number of ways.

Building via Dockerfiles is the most commonly used approach, but there are also other tools that can make it easier with less learning upfront and some other advantages.


If you’re not familiar with the specification for Dockerfiles, you can find it here. The basic layout looks something like this:

FROM debian:latest

ADD my-app-file /app/

CMD /app/my-app-file

The first thing we need is a starting point, and in this case, we’re using a debian image, and the latest version. There are also ones that are language-specific like python or golang and ones tied to specific distributions.

The next lines include whatever steps we need to prepare the image, and the last line tells the image what command to run when the image is executed. There are a lot of variations of this but these are the basics. How can we make it better? Well a real application that is a bit more complicated would make this easier. Here’s a very simple golang http server application:

package main

import ( "fmt" "net/http" )

func main() { http.HandleFunc("/", func (w http. …

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Developing Locally for the Cloud
David Dieruf May 21, 2020

Your app is destined for the cloud, but it’s going to meet some challenges along the way. First stop is the always fun whiteboarding session(s). Then come the sticky notes, which inevitably yield a backlog. Only when those two steps are complete does the Zen art of coding begin.

But ask yourself this: While whiteboarding the app’s design, how often is the developer’s local environment considered? Probably never. In fact, I bet during design a local environment doesn’t even make into the afterthoughts. Instead, it’s just one of those “figure it out” things.

Take, for example, the design of a microservice. Most likely it’s going to be dependent on an external configuration, like Spring Config. Ever consider how a developer is going to test on a config server locally? Do they have access to local containerization, like Docker? Or are they left to waste countless hours rigging up environment variables, only to find a totally different schema when the app is pushed to its platform?

I’ve been there and done that. It’s frustrating, wasteful, and breaks one of the most important of the 12 factors: No. 10, parity between environments. It’s also a personal favorite, and one I’ve been known to be ornery about.

The goal is not about following a good or bad design (although there’s plenty of room for bad decisions). It’s about …

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A Place to Build Apps and Build Skills
Bryan Friedman May 7, 2020

Developers and VMware. The pairing might not make sense to you at first. As an application developer, maybe you have only limited experience working with VMware software. It’s probably just the place where your software runs on-premises. Or it’s the thing you get access to a couple of days after putting in that infrastructure request ticket.

But make no mistake, VMware Tanzu is for you. If you are a developer working in a large enterprise, or even a small- to medium-sized business, you are now being asked to build “modern” applications or to “modernize” your existing apps. VMware Tanzu is a collection of software created expressly to help you with this application modernization effort. It brings together innovations via VMware’s acquisitions of Heptio, Bitnami, Wavefront, and Pivotal with lots of open-source DNA from projects like Kubernetes and Cloud Foundry. And don’t worry, this site isn’t about infrastructure software like vSphere or NSX. Instead, it covers the topics you need to know to write modern software: Spring, .NET, Python, RabbitMQ, Kafka, CI/CD platforms, and much more.

App modernization

So now you see how a VMware-hosted developer site can be focused on app modernization. But what exactly is meant by “app modernization”? Is it simply the latest in a long line of technology fads that just means more work for you?

It can sometimes feel like that. Change is hard, …

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