Attack of the Kubernetes Clones

One of the customers I support is using Kubernetes under Docker EE UCP (Enterprise Edition Universal Control Plane) and has been very impressed with its stability and ease of management. Recently, however, a worker node that had been very stable for months started evicting Kubernetes pods extremely frequently, reporting inadequate CPU resources. Our DevOps team was still experimenting with determining resource requirements for many of their containerized apps, so at first, we thought the problem was caused by resource contention between pods running on the node.

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Kubernetes Network Isolation

In the 1980s there was a funny television commercial for an insurance company that was debauching many other insurance companies. These hideous competitors trained their agents to “Say NO, deny the Claim!” thereby denying customers the benefits of the insurance policy they had purchased. It always made me chuckle and I still remember the chant to this day. I want to show you how you can do this, “Say no, deny pod access!” in Kubernetes using NetworkPolicies applied to your application deployments.

Kubernetes Network Isolation

Recently while working with a customer who is quite new to Docker and the world of Kubernetes, they were inquiring about how to isolate their applications from each other in a shared Kubernetes cluster.

In a previous blog post entitled Kubernetes Workload Isolation I discussed how customers have segmented their cluster by using a combination of VLAN’s, Collections, and Namespaces. But if you are not utilizing VLAN’s to segment your networking among VM’s and if you are not using Collections to separate VM’s into different RBAC groups then you will need a different approach.

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What is Container Orchestration?

Over the last two or three years I’ve given a similar presentation on containers to operations groups at clients, potential clients, conferences and meetups. Generally, they’re just getting started with containers and are wondering what orchestration is and how it impacts them. In this post, I will talk about what container orchestration is and provide several videos with simple examples of what it means.

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Kubernetes Workload Isolation

There are many images of ships with pin-wheel colored containers in a myriad of stacked configurations. In the featured image above you can clearly see three ships at dock loaded with containers. These ships have unique destination port cities across the globe each one carrying a distinct set of product for a discreet set of customers. These containers carry a payload.

Our virtual docker containers carry a workload. So, the ships vary in what containers they carry, where they are transporting it, and for whom it belongs to. We will talk about how to get our virtual containers loaded into a particular ship and entertain one solution to VM and container isolation.

Over the years Capstone has work in many vertical industries. Several of Capstone’s customers have extremely regulated environments such as the banking, insurance, and financial investment industries. These industry verticals typically need to comply with numerous governing standards and often have unique ways of interpreting and applying those regulations to there IT infrastructure. All of these regulations are aimed at restricting, or at least minimizing, covert intrusion.

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SSL Options with Kubernetes – Part 3

In the first two posts in this series, SSL Options with Kubernetes – Part 1 and SSL Options with Kubernetes – Part 2, we saw how to use the Kubernetes LoadBalancer service type to terminate SSL for your application deployed on a Kubernetes cluster in AWS and Azure, respectively. In this post, we will see how this can be done for a Kubernetes cluster anywhere using an Ingress resource.

Rather than using an external load balancer as the AWS and Azure cloud providers do for the LoadBalancer service type, an ingress uses an Ingress Controller to provide load balancing, SSL termination and other services within a Kubernetes cluster. A big advantage of using an ingress is its portability across all clusters regardless of the underlying infrastructure, i.e. cloud, virtualized or bare metal. Until recently, a disadvantage was an ingress only supported HTTP and HTTPS and you would need to use a NodePort service type for other protocols. However, NGINX has added support for other protocols to their ingress controller.

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Building Images in a Heterogeneous Cluster

Recently I was troubleshooting a customer problem in their on-premise cluster. But I was not sure where the problem lay. So I switched over to using my colleagues Docker Enterprise demo cluster that is running in Azure. In this heterogeneous cluster are 1 Universal Control Plan (UCP) manager, 1 Docker Trusted Registry (DTR), 2 Windows workers, and 1 Linux worker.

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Kubernetes NetworkPolicies in Docker Enterprise Edition

Kubernetes running under Docker UCP uses the Calico CNI plugin so that you can use Kubernetes NetworkPolicies to control pod to pod communication as well as communication between pods and other network endpoints.

This blog post will walk you through an example of configuring Kubernetes NetworkPolicies. We will block traffic from one namespace into another namespace, while still allowing external traffic to access the “restricted” namespace. As a high-level use case, we will consider the situation where a development team is working on multiple branches of a project, and the pods in the different branches should not be able to communicate with each other. If you are not familiar with the basic concepts of NetworkPolicies, see the Kubernetes documentation here.

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Help! I need to change the pod CIDR in my Kubernetes cluster


Your Docker EE Kubernetes cluster has been working great for months. The DevOps team is fully committed to deploying critical applications as Kubernetes workloads using their pipeline, and there are several production applications already deployed in your Kubernetes cluster.

But today the DevOps team tells you something is wrong; they can’t reach a group of internal corporate servers from Kubernetes pods. They can reach those same servers using basic Docker containers and Swarm services. You’re sure its just another firewall misconfiguration and you enlist the help of your network team to fix it. After several hours of troubleshooting, you realize that the problem is that you are using a CIDR (Classless Inter-Domain Routing) range for your cluster’s pod CIDR range that overlaps the CIDR range that the servers use.

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32-bit Apps in a 64-bit Docker Container

I started my career in December of 1989 at a company named Planning Research Corporation which contracted a considerable amount of work with the Department of Defense. I spent one year working in Fortran 77. The next 6 years were far more interesting to me as I dove into the world of ANSI C programming using the Kernighan & Ritchie bible. I still have my book on a shelf.

Our systems ran on 3 different Unix operating systems. We managed Makefiles that targeted SunOS, DEC Ultrix, and IBM AIX platforms. At times this was quite challenging. However, everything in this environment was 32 bit architecture; but what did that matter to me at the time? 64 bit processors didn’t come along for many more years.

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SSL Options with Kubernetes – Part 2

In the first post in this series, SSL Options with Kubernetes – Part 1, we saw how to use the Kubernetes LoadBalancer service type to terminate SSL for your application deployed on a Kubernetes cluster in AWS. In this post, we will see how this can be done for a Kubernetes cluster in Azure.

In general, Kubernetes objects are portable across the various types of infrastructure underlying the cluster, i.e. public cloud, private cloud, virtualized, bare metal, etc. However, some objects are implemented through the Kubernetes concept of Cloud Providers. The LoadBalancer service type is one of these. AWS, Azure, and GCP (as well as vSphere, OpenStack and others) all implement a load balancer service using the existing load balancer(s) their cloud service provides. As such, each implementation is different. These differences are accounted for in the annotations to the Service object. For example, here is the specification we used for our service in the previous post.

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