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Kubernetes – init containers, CNI and more

Certain questions about Kubernetes seem to come up again and again: What’s up with this init container stuff? What’s a CNI plugin? Why is Kubernetes complaining about pods not finishing initialisation? Kubernetes is a complex system with a simple overall purpose: run user  workloads  in a way that permits the authors of the workloads to not care (much) about the messy details of the hardware underneath. The workload authors are supposed to be able to just focus on Pods and Services; in turn, Kubernetes is meant to arrange things such that workloads get mapped to Pods, Pods get deployed on Nodes, and the network in between looks flat and transparent. This is simple to state, but  extremely  complex to implement in practice. (This is an area where Kubernetes is doing a great job of making things complex for the Kubernetes implementors so that they can be easier for the users – nicely done!) Under the hood, Kubernetes is leaning heavily on a number of technologies to make all this happen.
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What is Service Mesh?

  What  is a Service Mesh? What is a Service Mesh? A Service Mesh is a system that carries the requests and responses that microservices send each other. This traffic ultimately travels from Pod to Pod the same way it always has, but by passing through a Service Mesh layer as well much more advanced observability and control is possible. Think of a Service Mesh as a smarter network. Service Meshes are at the forefront of Cloud Native infrastructure. As Kubernetes revolutionised compute—the execution of services—Service Meshes are a massive value-add in networking. They’re also replacing a lot of boilerplate that used to happen in application code, but which is better done by the infrastructure. Much as projects like Terraform made the infrastructure team’s lives better, a Service Mesh is something that microservice developers and owners can use to better operate their applications. Service Meshes also augment the features of these applications, offering real  top-line  value, not just
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What happens from Keyboard to Kernel ?

Brief introduction to Linux kernel and shell Users new to Linux will want to familiarise themselves with the following: terminal  is a program that opens a window and lets you interact with the shell shell  is a program that takes commands from the keyboard and gives them to the operating system to perform. Bourne-Again shell, usually referred to as bash, which is the default shell for most Linux distributions. When you first login to a server, you will be dropped into the command prompt, or shell prompt, which is where you can issue commands to the server. The shell will forward its input (usually, from your own key presses) to the running program’s stdin, and it will forward the program’s output (stdout and stderr) to its own output (usually displayed on your screen). The shell is an interface that translates commands into some low-level calls to the kernel. kernel  is the essential center of a computer operating system, the core that provides basic services for all other p
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Making Python Programs Blazingly Fast

Let’s look at the performance of our Python programs and see how to make them up to 30% faster! Python  haters always say, that one of the reasons they don’t want to use it, is that it’s  slow . Well, whether specific program — regardless of the programming language used — is fast or slow is very much dependent on the developer who wrote it and their skill and ability to write  optimized  and  fast  programs. So, let’s prove some people wrong and let’s see how we can improve performance of our  Python  programs and make them really fast! Timing and Profiling Before we start optimizing anything, we first need to find out which parts of our code actually slow down the whole program. Sometimes the bottleneck of the program might be obvious, but in case you don’t know where it is, then here are options you have for finding out: Note: This is the program I will be using for demonstration purposes, it computes  e  to power of  X  (taken from Python docs): # slow
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