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In this quick fix, I’ll show you how to use a single-write, multi-read persistent block storage(ie: Google Persistent Disk or Amazon Elastic Block Store Volume) to store data on multiple nodes in a Kubernetes cluster using NFS.

Introduction

When you create a Kubernetes cluster, you have a few options for storing data in your pods:

Use the ephemeral container storage

You can just store data directly in the disk available in your container when you start it. This data is ephemeral, and restarting the container will wipe that data from the container itself. …


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Photo by chris panas on Unsplash

Let’s Encrypt is a fantastic service that allows anyone to generate an SSL certificate for their domain for FREE. It’s backed and funded by the biggest players in the industry, with the goal of creating a more secure Internet by enabling “SSL Everywhere”.

Many developers use it to generate certificates that encrypt their web traffic using HTTPS / TLS / SSL, but the way that they’re doing so may inadvertently leak their entire client list to anyone on the web. From a business perspective this can be catastrophic — especially when Non-Disclosure Agreements are in place to prevent such disclosure.

In this article, I’ll demonstrate the issue and provide some solutions that will keep your client list secure from this type of accidental disclosure. …


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In this quick fix, I’ll detail how I FINALLY solved an issue that’s been plaguing me for quite some time: Mounting a single file stored in a ConfigMap into an existing directory in a Docker container on Kubernetes.

Introduction

When I build applications to deploy with Docker, I expose configuration options through environment variables. This makes updating existing deployments simple — update the environment variable of a container and you can update the configuration.

However, many applications deployed with Docker were not originally designed to run in Docker. …


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Image by Radek Grzybowski

I love Inkscape. It’s one of my favorite vector graphics programs. And when XQuartz (the X-11 window manager for Mac) stopped being supported, I couldn’t run it on my Mac anymore. That made me sad.

I love Inkscape. It’s one of my favorite vector graphics programs. And when XQuartz (the X-11 window manager for Mac) stopped being supported, I couldn’t run it on my Mac anymore. That made me sad.

I’m also a huge fan of containerization in general. …


Responses to Bitcoin Interview Questions

I recently did an interview with Ryan Ringer, a computer science student and technologist, in which I answered questions about Bitcoin. Below are some of my answers to his questions.

RR: Why is bitcoin of any value?

JO: This is a simple question with a surprisingly complex answer. To figure out what gives bitcoin value, we first have to think about what gives currency value. It turns out, currency as a concept isn’t all that valuable. Instead, it REPRESENTS something of value.

I’ll use an example. Let’s say you and I wish to perform a transaction. I sell beaver pelts and you sell eggs. If we use a straight barter, then if you don’t want beaver pelts or I don’t want eggs then we can’t trade. However, what if there was something we could trade for that EVERYONE wanted — like gold? I can trade my beaver pelts for gold, and then trade that gold with anyone for anything else I want or need. …


Mastering bitcoin is a modern masterpiece. It describes, in easy to understand terms, how Blockchain and Bitcoin work from a fundamental level as well as a very detailed technical level. When you have a moment, purchase the book and support the very worthy author, Andres Antonopolous. However, in the spirit of open-ness, O’Reilly (the publisher) has released the source code for the book on Github. In this article I’ll show you how to generate your own English language PDF version from the public, open-source source files.

Let’s get started…

Docker and ASCIIDoctor

Docker is a deployment system that allows you to easily install software in “containers”, which are essentially micro-sized virtual machines that have all of the configuration needed to “just start running” your applications. We’ll use Docker to run our conversation application so you don’t need to do much in the way of installation. If you don’t have Docker installed already, you’ll want to do that before we get started. …


Part one of becoming a Jolly Rancher®

In this first of a 3-part series on container orchestration with IBM Cloud and Rancher, we’ll take a sneak peek at Rancher 2.0, a visual container orchestration and management tool. We’ll also show you how to run and manage containers across a Kubernetes cluster, and show you how to deploy containers within an existing IBM Cloud Container Service Kubernetes cluster.

You can’t throw a rock at a technical conference today without hitting someone that’s building applications using Docker. Linux containers technology, and in particular the Docker implementation of them, has drastically changed the way server-side applications are being deployed and developed. Gone are the days of configuring multiple servers and spending hours tuning settings or creating Ansible recipes; now you can simply spin up a container and you have a pre-configured application that’s already running and ready-to-go. …


Whether you’re working on a small toy app just for fun or conquering the “Next Big Idea™”, writing and prioritizing your user stories should be your very first step. Prioritizing helps you figure out which tasks you should be working on first. If you’re working on a contract basis, prioritizing helps you communicate features with your client and remain on time or budget. You can use priorities to provide “flex requirements” which will get implemented should the time and budget permit, as opposed to “system critical requirements” without which the project is incomplete or unusable.

In this article, I’ll briefly explain what the MoSCoW method is, and how you can use it to prioritize your user stories. …


When you’re preparing for a technical interview, it can be difficult figuring out what you should study. Do you spend your time brushing up on algorithm analysis? Do you study the programming languages they have listed in the job requisition that you’re rusty on? Where do you start?

To take a page (the front page specifically) from Hitchhikers Guide to the Galaxy: Don’t Panic!

When doing a technical interview, there are 4 basic categories of technical interview question that you’ll get. Knowing what these are, and developing a strategy for answering them, will help you ace any technical interview.

The Four Categories of Technical Interview Question

1. Situational Problem Solving Question

“Tell us about a time that you were working in a team and had a conflict. How did you resolve…


Hint: They have nothing to do with history.

If you went to elementary or middle school in the 1980’s and early 1990’s, you no doubt had the pleasure of playing some of the most fun and well-made educational video games ever created. “The Oregon Trail” was less of a game and more of a childhood bonding experience. We mourned the loss of our friends as they died of various ailments on the trail.

I found an Apple ][ emulator Online recently that came with a copy of The Oregon Trail. …

About

John O'Connor

Entrepreneur. Engineer. Educator.

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