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Case

Get the HOME environment variable of the executing user during sudo with ansible.

When using with ansible, it becomes root’s. This is a problem when you want to place files under the home directory of the execution user, such as when building a development environment. In ansible, the execution user name is set to, so you can use this to get the HOME environment variable of the execution user and use it.

By pre_taskexecuting the above task with , the HOME environment variable of the executing user is set, so you…


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Record your intent with a Kubernetes object

Kubernetes objects are persistent entity 1 on Kubernetes . Kubernetes uses these entities to represent the state of the cluster.

The following contents can be expressed:

  • What containerized applications are running (and on which nodes they are running)
  • Resources available from those applications
  • Policies on how the application behaves, such as restarts, upgrades, fault tolerance policies, etc.
  • Once you create an object, Kubernetes always keeps it in existence.

Manipulating Kubernetes objects using the Kubernetes API

When working with Kubernetes objects, you must use the Kubernetes API regardless of whether you create, modify, or delete them.

kubectl command line interface

If you use the kubectl command line interface, this CLI will issue…


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Introduction

For those of us who don’t want to edit resources with an editor that launches with a command, there is command , so let’s take advantage of it. The nice thing about the patch command is that you don’t have to handwrite it in the editor. Since resources can be changed with one liner, it is also suitable for embedding in shell scripts.

Let’s test this !

Run example deployment


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Generally, the container image is used by pulling the one pushed to the container registry . There is also a method of exchanging container images as files without going through the above registry.

Export the container image to a file

You can export it to a tar file with a command.


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Introduction

Sometimes you want to quickly prepare a kubernetes environment for learning purposes and for small experiments. I introduce a free kubernetes environment that can be used on the browser, which is convenient in such a case.

First of all, I will introduce the kubernetes environment described in the official document.

Hello Minikube — Kubernetes

Launch Terminal Click the button to use minikube on your browser . Minikube is a kubernetes environment for development and is currently a single node cluster.

Learn Kubernetes Basics

This is also a tutorial described in the official kubernetes documentation. Interactive Tutorial You can operate minikube on the browser by going to the…


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What is Helm

Helm is a package manager for Kubernetes, an OSS hosted by CNCF .
The package is published in the format of Chart in Artifact Hub and the repository of each OSS, and you can also make your own. You can deploy Chart to a kubernetes cluster (“k8s cluster”) with one command

Major Chart Repositories

Preparing a k8s cluster

Please prepare your favorite environment. The following is recommended.

Public cloud faction:

On-premise:

Environment

  • Ubuntu 16.04
  • Vagrant

Install Helm

Let’s get Helm ready to use, we can install helm in two way’s

  • From…


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Kubernetes network service related components

The network service related components of k8s are further divided into the following categories.

  • Load Balancer / Ingress: Load balancer (LB), Ingress is a layer that receives communication from outside the cluster and transfers it into the cluster. In particular, LB is “outside the cluster”, so it is often placed separately from K8s. Or the component of Ingress may also be the LB.
  • DNS / Service Discovery: Performs name resolution and monitoring of pods and containers inside the cluster . It is a traffic control role in the cluster. …


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Introduction

Some time ago I started studying Splunk, so I’d like to look back on the past and summarize useful study methods and useful site information, about splunk which I used when I started studying Splunk.

First few thing to do

If you want to study Splunk from now on, first prepare an environment where you can study.

  • Install Splunk and import sample data: Splunk is free to use as long as you capture 500MB of data per day. If you just study, it will be enough capacity. The computer to install is also compatible with Windows / Linux / Mac, and if you have enough…

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What exactly is Istio?

Istio is an OSS for securely managing microservices and is a member of the CNCF like Kubernetes.

As microservices progressed, Service Mesh became larger and more complex due to requests such as allocating only 20% access to A/B testing and canary releases . Istio has been developed to solve this problem of managing complex service meshes cannot keep up. Key features include authentication and monitoring between services, and flexible load balancing at L7. Currently it only supports Kubernetes, but it seems that it will support other platforms in the future. (Some functions such as key management are compatible with bare…


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Introduction

If we use Helm2 in our environment, it would be good to think about updating it to version 3, due to the fact that it will soon cease to be supported

What is HELM ?

Simply put, it’s a package manager like yum or apt for Kubernetes.

Helm2 End Of Life

Users installing applications using Helm2 on Azure Kubernetes Service receive the following email.

Upgrade from using Helm 2 to Helm 3 for your AKS cluster(s)
You’re receiving this email because you have Azure Kubernetes Services (AKS) cluster(s) running Tiller, which is installed as part of Helm 2.

It’s a message recommending an update to Helm 3 as…

Maciej

DevOps Consultant. I’m strongly focused on automation, security, and reliability.

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