User Guide on

Kubernetes Materials

Mon, 20 Oct 2025 10:22:37 +0900

1. Kubernetes(k8s) Materials

Here are some commonly available documents.

Some of the books currently available do not differ much from the Japanese translations on the official website, so please try to learn online first.

However, for advanced use, such as extending the functionality of Kubernetes itself using Kubebuilder or other tools, commercially available books will be useful.

There are also some that cover older versions. If what is written does not work, please check the target Kubernetes version.

Kubernetes Internal Mechanisms [For Intermediate and Advanced Users]

Mon, 21 Apr 2025 13:04:22 +0900

Summary

This section describes the components that make up Kubernetes (K8s) and explains how Kubernetes works.

References

The purpose of this document is to explain what you might need to know to read these documents.

Basic Configuration of K8s

The official documentation includes the following diagram.

About ThinkPad (Client Environment)

Mon, 21 Apr 2025 11:54:10 +0900

1. Client environment

In the seminar room, we provide ThinkPads with Xubuntu installed for your work.

OS: Xubuntu (an LTS distribution with the lightweight Xfce desktop environment instead of Ubuntu’s default Gnome3)
Packages: ibus, language-pack-ja, docker, kubectl, etc.

For network information, such as IP addresses, see the Network Configuration page.

This computing environment (including the ThinkPads in Seminar Room 10) is personally managed by Abe.
Please report any problems immediately after you log in.
(e.g., missing home directory, missing applications, questions about how to use the system, etc.)

Harbor - DockerHub Alternative

Mon, 21 Apr 2025 12:53:35 +0900

1. Harbor - Docker Registry Alternative

https://goharbor.io/ - Official Site

2. Basic information of Harbor

URL: https://inovtst9.u-aizu.ac.jp/
Availability: Only within AINS netowrk
ID: Use your AINS ID

If you enable your namespace in kubecamp.u-aizu.ac.jp, you will be ready to use the Harbor.

Private Project Name: "AINS ID".private
Public Project Name: "AINS ID"

Please check your status logging in the Harbor, https://inovtst9.u-aizu.ac.jp/.

3. Getting started

This section describes basic usage.

3.1. Log in to Harbor

Go to https://inovtst9.u-aizu.ac.jp/ and log in with your AINS ID and password.

Getting Started with KubeCamp

Sun, 18 Feb 2024 22:35:16 +0900

Getting Started with KubeCamp

KubeCamp is a kubernetes cluster available to all AINS users.

Because SCCP members are given priority access to resources, there are limitations on the resources (memory, CPU, storage, etc.) available to other guest users on this Kubernetes cluster.

Please check Limitations for more information.

Useful Links

Getting Started

The system is utilized through the kubectl command.

Before executing the kubectl command (Only needed once)

When you press the Create Namespace button from the dashboard, essential resources such as namespace objects will be created in the K8s cluster.

Setup the kubectl command

Mon, 21 Apr 2025 12:01:52 +0900

kubectl is an essential command-line tool for managing Kubernetes clusters, allowing users to deploy applications, inspect and manage cluster resources, and view logs.

This document explains how to set up the kubectl command for use.

1. For users of kubecamp.u-aizu.ac.jp

1.1. For Those Who Have Used the kubectl Command in the Past

If you have already placed your ~/.kube/config file, please update the correct value of the id-token: key.

If you haven’t done so, please replace the shown configuration text in your ~/.kube/config file.

Persistent Volume (PV&PVC)

Wed, 01 Jul 2026 08:52:24 +0900

1. PV and PVC

Persistent Volume(PV) is a feature of K8s that provides persistent storage like HDD/SSD.

In a container-based virtualization environment, when a process terminates, the contents previously stored inside are destroyed and initialized.

This is excellent in that if a process is contaminated from the outside, such as by a virus, it can be reset to its pre-contaminated state by restarting it, thus ensuring its integrity. However, this feature can be a problem for applications such as database servers, where the purpose is to store data.

Reverse Proxy

Wed, 01 Jul 2026 08:55:42 +0900

1. User list

We are preparing a mechanism to access the application on Kubernetes running in the seminar room from the campus. Please make sure that your Namespace (AINS-ID) exists in the user list below.

2. Basic Reverse Proxy usage

In the Ingress configuration prepared for this environment, each user connects to "<namespace name>-svc" in a service that they are free to do so.

This configuration accesses only one type of pod(s) and does not allow external access to multiple web applications such as nginx, dvwa, etc.

S3 Compatible Object Store (Latest Version)

Mon, 21 Apr 2025 12:56:00 +0900

1. S3 compatible object store

We are preparing an S3 compatible Object Store using Minio

2. References

For basic usage of Minio’s Object Store, please refer to the following document.

official Minio documentation

3. Prepared objects

To avoid interfering with each other, they are organized as follows.

Buckets cannot be created freely. Buckets are prepared as "username-bucket" with unique key and secret for each user.
information for using these (information equivalent to AWS_ACCESS_KEY and AWS_SECRET_ACCESS_KEY) is stored in secret/objectstore of each user’s namespace.
You can access to your bucket thourgh the following URL.
- http://192.168.100.161:9001/

Load Balancer (LB)

Thu, 14 Mar 2024 09:40:54 +0900

The Kubernetes description provided by platforms such as AWS and GCP uses a load balancer (LB) that is assigned a global IP address for communication with the outside world.

In our Kubernetes cluster, the MetalLB is used to assign IP addresses in the range 192.168.100.160-199/24.

FYI: Deploying MetalLB on Kubernetes prepared by Kubespray.

The LB assigned the address of 192.168.100.0/24 cannot be accessed from any other places except Seminar Room 10, such as exercise rooms and ains-wifi.

[Unrevised] [docker] Official Docker Tutorial Part 2

Wed, 01 Jul 2026 08:56:32 +0900

1. Preparation work before using Docker

Starting April 2023, Docker will be run as a user with non-root privileges, rootless mode.

Before the change, we had to run docker as a privileged (root) user, as in docker, but from now on we should run docker as docker without "sudo".

To enable the rootless mode, you will need to add the DOCKER_HOST environment variable to your ~/.profile and a working area on a non-NFS file system in your ~/.config/docker/daemon.json file.

[docker+k8] How to build a full-text search engine using Apache Solr

Mon, 21 Apr 2025 12:27:57 +0900

1. [docker+k8] How to build a full-text search engine using Apache Solr

The work procedure assumes ThinkPad (Ubuntu 20.04) in Seminar Room 10, but the same work can be done on Linux (CentOS) in the exercise room, macOS, and Windows 10.

macOS environment

Java development environment (JDK 11 amd64) installed (Adoptium OpenJDK)
Docker Desktop for macOS installed (Official Guide)

Windows 10 environment

WSL2 environment is set up (official guide)
Install Ubuntu 20.04 LTS from MS Store (official store)
Install Docker Desktop for Windows (Official Guide)
Java development environment (javac command) is installed in WSL2 environment (Ubuntu 20.04 LTS) (install default-jdk)

[docker+k8s] Creating a Search Engine WebApp with OpenAPI+Sinatra

Mon, 21 Apr 2025 12:46:16 +0900

1. Creating search page by OpenAPI+Sinatra

Using Docker, let https://opm00h.u-aizu.ac.jp/solr/api/v1/search handle the search process and create an application to create and display a web page that displays the search results. Create an application to create and display a page that displays the search results.

1.1. About OpenAPI and openapi-generator

OpenAPI is the name of the specification created by the OpenAPI Initiative, an organization that aims to standardize methods for writing APIs.

[k8s] k8s Official Stateless Sample Application 1 (Nginx)

Wed, 01 Jul 2026 08:54:13 +0900

1. Workflow

This section describes how to run the official examples available on kubernetes.io on this Kubernetes cluster.

Tutorial 1: k8s official site::Stateless Application:Exposing an External IP Address to Access an Application in a Cluster]

The work here is designed to be run on a ThinkPad in a seminar room.

If you wish to run this on your own PC or in the seminar room, please keep the following points in mind.

[k8s] k8s Official Stateless Sample Application 2 (Guestbook)

Fri, 15 Dec 2023 12:02:35 +0900

1. Example: Deploying PHP Guestbook application with Redis

This section describes how to run the official example published on kubernetes.io on this k8s cluster.

Tutorial 2: k8s official site::Example: Deploying PHP Guestbook application with Redis

This is a guestbook (doodle) application written in PHP language using a Non-SQL database server called Redis.

1.1. Basic method

I’m going to look at the Tutorial 2 page and run the commands, Here is a list of commands with -n $(id -n) added mainly.

[Unadvised] [k8s] ............. Stateless Sample Application 3 (Socket.IO Guestbook)

Mon, 21 Apr 2025 12:34:30 +0900

1. Summary

The officially provided Guestbook application did not automatically display messages when multiple users connected, requiring reloading.

In this article, I will describe an application and its internal structure that uses socket.io to immediately reflect written content.

A sample application using socket.io is available at the following URL.

https://socket.io/get-started/chat

Based on the above getting started tutorial, the container image is available at the following URL.

https://hub.docker.com/r/yasuhiroabe/socket-guestbook

Sample code for the final application with user authentication enabled is available at the following URL.

[keepalived] Building a keepalived cluster using APU/APU2

Thu, 29 Jan 2026 15:36:44 +0900

1. Summary of work

This tutorial is designed to give you a taste of two features of keepalived: load balancing and high availability (HA, High Availability).

One of the key technical elements is VRRP. VRRP allows multiple machines to share a single IP address, and even if one machine goes down, the other machines can take over the IP address and continue processing.