Coders Classroom

Kubectl provides autocomplete support for bash which can save us lot of typing. Bash on Windows using Git bash 1. Install Git bash from https://git-scm.com/downloads if it is not available in your computer 2. Navigate to “C:\Users\<yourname>” from Git bash cli 3. Run following command to get kubectl autocompletion bash commands and save into “kubectl-completion.bash” file > kubectl completion bash > ~/kubectl-completion.bash 4. Create or Update .bashrc file source > echo 'source ~/kubectl-completion.bash' >> .bashrc 5. Restart Git bash and start typing kubectl get po ( press [TAB] key ) Bash on Windows using Conemu/Cmder It is an another handy multi and split tab windows terminal. It supports multiple command terminals like cmd, PowerShell, bash and etc. 1. Install Git bash from https://git-scm.com/downloads if it is not available in your computer 2. Install C...

Kubernetes for Developers #10: Kubernetes Pod YAML manifest in-detail

In General, K8 resources are usually created using YAML or JSON manifest. YAML Structure : YAML is a Indentation based and superset of JSON, which means any valid JSON file is also a valid YAML file. There are two types of structures we mostly use. Map : It is key-value pair like Json Object. Ex : simple key-value structure where key and value are strings #yaml apiVersion : v1 kind : Pod #json { "apiVersion" : "v1" , "kind" : "Pod" } Ex : complex key-value structure where value act as another Map #yaml apiVersion : v1 kind : Pod metadata : name : pod-nginx #json { "apiVersion" : "v1" , "kind" : "Pod" , "metadata" : { "name" : "pod-nginx" } } List: It is sequence of values like Json Array represented using...

Kubernetes for Developers #1: Kubernetes Architecture and Features

Kubernetes(K8) is an open-source container orchestration tool used for automating deployment, scaling and management of containerized applications. Features: 1. Self-Healing : It restarts container that failed or kills the container that do not respond to container health check endpoint. It always maintains user defined number of replicas 2 . Secret and configuration management : It maintains an application level configuration and secrets in a separate location. So, it can be modified without re-building and deploying container 3. Horizontal scaling: It is easy to scale-up/down containers with a simple command or automatically based on CPU usage. 4. Automatic bin packing: It automatically places containers into the required Worker nodes based on specified CPU/Memory. 5. Storage orchestration : It allows to mount a local storage or cloud providers 6. Automated rollouts and rollbacks: It allows to rollout new application changes by spinning up new container without killing existing conta...

ClosedXML – Read/Write Excel File Using C#.NET

Many of Windows/Web applications having requirement that, get the data from database and import into Excel file. There are several ways for developers to write data into Excel using C#.NET. See the following options 1. Microsoft Excel Interop 2. Microsoft Open XML SDK 3. ClosedXML Microsoft Excel Interop: 1. Office Interop needs Excel driver to be installed on the machine which is generating excel file 2. Excel installed version must match with the interop assembly version 3. Interop calls are expensive in terms of performance Microsoft Open XML SDK: 1. Open XML is developed by Microsoft 2. No need to install Excel driver on the machine 3. It is a document format consists of XML parts stored in ZIP package 4. It is the default format for MS Office 2007/2010 ClosedXML: 1. It is wrapper on Open XML specification 2. No need to install Excel driver on the machine 3. It makes easier for developers to ...

Kubernetes for Developers #14: Kubernetes Deployment YAML manifest in-detail

In previous articles, we have learned how to create or manage Pod manually. However, in real-world use cases, The Pod creation/re-creation should be done automatically and remain healthy without manual intervention, that’s where K8 Deployment comes into the picture. It helps us to manage set of identical pods without creating/updating/deleting pods manually. It makes desired number of identical pods always stay up and running automatically without user intervention. It is a high-level resource, the actual pods are created and managed by the ReplicaSets, not by the Deployment directly. ReplicaSet constantly monitors the list of running pods and makes sure the actual number of pods are always matching the desired number of pods. It there are only few pods are running, it creates new replicas from a pod template. If there are many pods are running than desired number, it removes the excess replicas. Deployment YAML file contains both desired replica count and Pod template in it. Therefor...

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