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Kalyan Halder

1 month ago

How to Add a New Node to Kubespray Manased Production Ready Kubernetes Cluster

I have a production ready kubernetes cluster managed by kubespray. Now I need to add additional node to the cluster. Here I am showing you how you can add a additional node to your cluster. Here my existing cluster -

╰─ kubectl get nodes                                                                                                                                        
NAME    STATUS   ROLES                  AGE    VERSION
node1   Ready    control-plane,master   28d    v1.21.4
node2   Ready    control-plane,master   28d    v1.21.4
node3   Ready    <none>                 28d    v1.21.4

Now I want to add a new node4 to the cluster. First of all I need to edit the existing ansiable host file which is inventory/mycluster/hosts.yaml

# file path - inventory/mycluster/hosts.yaml
all:
  hosts:
    node1:
      ansible_host: 10.180.63.193
      ip: 10.180.63.193
      access_ip: 10.180.63.193
    node2:
      ansible_host: 10.180.63.151
      ip: 10.180.63.151
      access_ip: 10.180.63.151
    node3:
      ansible_host: 10.180.63.30
      ip: 10.180.63.30
      access_ip: 10.180.63.30
    node4:
      ansible_host: 10.180.63.160
      ip: 10.180.63.160
      access_ip: 10.180.63.160
  children:
    kube_control_plane:
      hosts:
        node1:
        node2:
    kube_node:
      hosts:
        node1:
        node2:
        node3:
        node4:
    etcd:
      hosts:
        node1:
        node2:
        node3:
    k8s_cluster:
      children:
        kube_control_plane:
        kube_node:
    calico_rr:
      hosts: {}

I added node4 information in the above hosts.yaml file. Here my node4 information -

#my node4 information 

    node4:
      ansible_host: 10.180.63.160
      ip: 10.180.63.160
      access_ip: 10.180.63.160

Now run the cluster.yml file to add the new node to the cluster.

ansible-playbook -i inventory/mycluster/hosts.yaml cluster.yml -u root -b -l node4

Where,

-i : inventory file to be used
cluster.yml : playbook to deploy a cluster
-u root : the user account which we have created on all nodes for password-less ssh access.
-b : enable become – sudo access is needed for installing packages, starting services, creating SSL certificates etc.

Wait to finish the process.

All done! Now verify the newly added node4 to the cluster.

╰─ kubectl get nodes                                                                                                                                        
NAME    STATUS   ROLES                  AGE    VERSION
node1   Ready    control-plane,master   28d    v1.21.4
node2   Ready    control-plane,master   28d    v1.21.4
node3   Ready    <none>                 28d    v1.21.4
node4   Ready    <none>                 102s   v1.21.4

Now node4 is a part of your cluster.

How to Add a New Node to Kubespray Manased Production Ready Kubernetes Cluster

Vika , Razu and
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Kalyan Halder

2 months ago

How to Add a WSO2 API Manager Federated Identity Providers

If we want to use a federated identity providers as key manager we can do it easily. Here I am showing the primary settings of OAuth2/OpenID connect configuration -

Irina , Mizanur and
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Kalyan Halder

2 months ago

How to generate kubernetes dashboard access token

1. Create the dashboard service account

Run the following command to create a service account

kubectl create serviceaccount kubernetes-dashboard-admin-sa -n kube-system

The command will create a service account in the namespace of kube-system. replace your namespace instate of kube-system

2. Bind the service account to the cluster-admin role

kubectl create clusterrolebinding kubernetes-dashboard-admin-sa --clusterrole=cluster-admin --serviceaccount=kube-system:kubernetes-dashboard-admin-sa

3. List Secretes

kubectl get secrets -n kube-system

4. get the token from secret

kubectl describe secret kubernetes-dashboard-admin-sa-token-lj8cc -n kube-system

Here your secret name can be different. Now copy the token and use it to login kubernetes dashboard.

Lucky , Bidyut and
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Kalyan Halder

2 months ago

Deploy a Production Ready Kubernetes Cluster With lxc Container and Kubespray

I am going to show the workground how you can use lxc container to create a production grade cluster. Though its hard to create kubernetes cluster with lxc container but its possible. So lets see how we can solve all of those challenges step by step

Step 1: Prepare host machine

a) edit following file

nano /etc/sysctl.conf
# Uncomment the next line to enable packet forwarding for IPv4
net.ipv4.ip_forward=1

b) disable firewall

ufw disable

c) disable swap

swapoff -a; sed -i '/swap/d' /etc/fstab

d) update sysctl settings for kubernetes networking

cat >>/etc/sysctl.d/kubernetes.conf<<EOF
net.bridge.bridge-nf-call-ip6tables = 1
net.bridge.bridge-nf-call-iptables = 1
EOF
sysctl --system

Step 2: Create lxc profile

config:
  boot.autostart: "true"
  linux.kernel_modules: ip_vs,ip_vs_rr,ip_vs_wrr,ip_vs_sh,ip_tables,ip6_tables,netlink_diag,nf_nat,overlay,br_netfilter,nf_conntrack,xt_conntrack
  raw.lxc: |
    lxc.apparmor.profile=unconfined
    lxc.mount.auto=proc:rw sys:rw cgroup:rw
    lxc.cgroup.devices.allow=a
    lxc.cap.drop=
  security.nesting: "true"
  security.privileged: "true"
description: Default LXD profile
devices:
  eth0:
    name: eth0
    network: lxdbr0
    type: nic
  root:
    path: /
    pool: default
    type: disk
name: microk8s
used_by:
- /1.0/instances/node1
- /1.0/instances/node2
- /1.0/instances/node3

Step 3: Create a linux container

lxc launch -p default -p microk8s ubuntu:21.04 node1

Step 4: Inside container do following

a) following command should return output

conntrack -L
modinfo overlay

b) if above command output error then its seems that there some karnel related problem. Install and fix karnel issue

sudo apt install linux-generic
sudo apt install --reinstall linux-image-$(uname -r);
sudo apt install --reinstall linux-modules-$(uname -r);
sudo apt install --reinstall linux-modules-extra-$(uname -r);

this should fix karnel related issue.

c) Recent kubernetes versions want to read from /dev/kmsg which is not present in the container. You need to instruct systemd to always create a symlink to /dev/console instead:

echo 'L /dev/kmsg - - - - /dev/null' > /etc/tmpfiles.d/kmsg.conf

if it not working then run following

echo 'L /dev/kmsg - - - - /dev/console' > /etc/tmpfiles.d/kmsg.conf

if it still not work then do following

# Hack required to provision K8s v1.15+ in LXC containers
mknod /dev/kmsg c 1 11
echo 'mknod /dev/kmsg c 1 11' >> /etc/rc.local
chmod +x /etc/rc.local

d) if you need to load any module then you can run following comman

# cmd    module name
------------------------
modprobe br_netfilter

Thats all. Now follow the Kubespray official document.

To access k8s cluster without execing into master node

Download the kubectl command into your local.

which kubectl
# output: /usr/bin/kubectl

Create .kube directory

mkdir ~/.kube

copy config from kmaster into .kube directory

lxc file pull kmaster/etc/kubernetes/admin.conf ~/.kube/config

#check cluster
kubectl get nodes

Deploy a Production Ready Kubernetes Cluster With lxc Container and Kubespray

Maria , Kristina and
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Kalyan Halder

2 months ago

How to Permanently Solve "Temporary failure in name resolution" Issue

Permanently Solve Temporary Failure in Name Resolution Issue

Sometimes we face issue like

[email protected]:~$ ping jadukori.com
ping: jadukori.com: Temporary failure in name resolution

We can easily solve the issue by editing /etc/resolv.conf

just add to the file

namespace 8.8.8.8

But the solution does not work when system reboot.

So lets solve permanently the problem.

Step 1: Install following lib

sudo apt install resolvconf

Step 2: edit following file

nano /etc/resolvconf/resolv.conf.d/head

add following record to the file

nameserver 8.8.8.8
nameserver 8.8.4.4
nameserver 1.1.1.1

now save and reboot the system.

Congratulation!! We solve the problem permanently.

Jennifer , FinderBD and
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Habib Hasan posted in সরকারি চাকরি

11 months ago

Prime Minister’s Education Trust Job Circular
public Job
Job Type: Full-time
Salary: 35500 - 67010 tk. per month
Application Deadline: 2021-01-13

Applications are invited from genuine Bangladeshi nationals for direct appointment to the following posts in the Prime Minister's Education Assistance Trust. Job summery at a glance -

Name of Organisation	Prime Minister’s Education Assistance Trust
Circular Publish Date	21st December 2020
Source	Official Website
Job Type	Government Job
Post Name	Programmer
Number of Post	1
Nature of Job	Full time
Age	35 years
Educational Qualification	As per circular
Salary	35500- 67010
Job Location	Dhaka
Official Website to Apply	http://www.pmeat.gov.bd/ or http://pmeat.teletalk.com.bd
Deadline	13th Jan 2021

Prime Minister’s Education Trust Job Circular

Tara , Fokrul and
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Habib Hasan posted in সরকারি চাকরি

11 months ago

Department of Agricultural Extension Recruitment Circular
public Job
Job Type: Full-time
Salary: 18300 - 19300 tk. per month
Application Deadline: 2020-12-27

কৃষি আবহাওয়া তথ্য পদ্ধতি উন্নতকরণ প্রকল্পের নিয়োগ বিজ্ঞপ্তি।

Recruitment- Notification
summery at a glance -

Name of Organization	Department of Agricultural Extension-Government DAE
Circular Publish Date	11 December 2020
Job Type	Government Job
Number of Post	2
Nature of Job	Full time
Age	From 18 to 30 years
Educational Qualification	As per circular
Fee	100
Official Website to Apply	http://www.dae.gov.bd
Deadline	27 Dec 2020

Recruitment to the following posts on full temporary basis for the duration of the project "Agro-Climate Information System Improvement Project" being implemented by the Department of Agricultural Extension. Applications are invited from permanent citizens of Bangladesh for:

Position Name

Educational Qualifications and Experience

Accountant 1 (one)

Minimum Bachelor in Commerce from a recognised University. Must have knowledge of MS Word, Excel, PowerPoint to help with accounting. Experience in public procurement, government audit system, ADP and IDA finance system will be preferred. Must have at least 5 (five) years of experience in accounting or financing. The age limit is relaxed for the more experienced.

Office Assistant

1 (one)

Minimum bachelor's degree from a recognised university. Must have experience in preparing letters, reports, other documents through MS Word, Excel, PowerPoint etc. Must have at least 2 (two) years experience in office secretarial work. The age limit is relaxed for the more experienced.

Department of Agricultural Extension Recruitment Circular

Md suzan , Tara and
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Habib Hasan posted in সরকারি চাকরি

11 months ago

Job circular at Ministry of Defense – 2020
public Job
Job Type: Full-time
Salary: 8000 - 26000 tk. per month
Application Deadline: 2021-01-04

Ministry of Defense published a job circular and invited applicants to apply within 04 Jan 2021. Job summary at a glance -

Name of Organization	Ministry of Defence (MOD)
Circular Publish Date	12th December 2020
Job Type	Government Job
Number of Post	38
Nature of Job	Full time
Age	From 18 to 30 years
Educational Qualification	As per circular
Fee	6 - 112
Official Website to Apply	http://mod.teletalk.com.bd or https://mod.gov.bd
Deadline	04 Jan 2021

Apply Instruction:

Interested and Eligible Candidates will apply on-line. To use on-line follow the instruction below.

The application process very easy. You have to Fill- up the application form with the needed information.

First of all, visit http://mod.teletalk.com.bd and choose your Position.

Upload your Color photograph and Signature. The photograph Size should 300×300-pixel, most 100kb, and JPG Format. The signature size should 300×80-pixel, most 60KB and JPG Format.

Then submit the application form. You will get the preview then download the applicant copy.

You should not apply on the last day of the job circular. Because the last date may not work properly. So, apply early to avoid any kinds of problems. To finish your application, you must have to pay the application fee. You can through telitalk mobile network by sending SMS.

Job circular at Ministry of Defense – 2020

Kalyan , Md suzan and
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Habib Hasan posted in Travel Bangladesh

11 months ago

Avoid all mistakes on the trip

Usually Experienced tourists give advice on what to do or see during the trip. But what do you know about what not to do on the trip? Usually, any tourist makes several mistakes on the trip.

You may have to spend extra money for those mistakes or you may be wasting time or you may have missed a trip to a beautiful place. But by avoiding those mistakes, you can travel smart at a very low cost. Let's take a look at the things that should be avoided while traveling.

Do not take food from main tourist places

Usually, the price of food at a tourist main place is higher than any other place. When the restaurants realize that tourists may not come here a second time, they do not think much about the quality of the food. The farther you go from the tourist main place to the local restaurant, you'll find better local food at a lower cost.

Take travel insurance

While this may seem like an extra expense, accidents can happen at any time. You should be highly prepared for that. Travel insurance will protect you in case of loss of your hobby camera, injury to limbs, etc.

Also, if you face these problems without insurance, it can cost much extra money. So it is wise to take out travel insurance.

Do not exchange money at the airport

When you travel to another country, you have to exchange money. But never do that from the airport. Usually, the exchange rate is the lowest at the airports.

Exchange money from ATM or credit card. If that is not possible, do it from the nearest bank. You can exchange money at a very good rate from ATM or bank.

Taxi service should take less

Usually, the taxi service is more everywhere. However, this service can be taken if the rent can be shared with two or three people. So it is better to take public services for travel.

Hostel accommodation

Most people think the hostel is a very dirty, smelly environment that is chosen by relatively indigent travelers. It used to be like this but now it has changed a lot. Many hostels are much cleaner than hotels. You will also find hostels with various facilities including pool games, TV, laundry. Hostels are a good option for low-cost backpack travelers.

Not booking hotels and flights much earlier

The earlier a trip is booked, the more likely it is that the cost will increase. Apparently, you are being offered a discount on a flight or hotel shortly before the start of the trip but you cannot accept it because you have booked in advance. So wait for the offer. Understand the situation and book a hotel or flight at different times.

Go to the local tourist office

Go to the tourist office of the place you are traveling to. There you will find maps, guides or a good idea of where to stay. Their job is to help tourists. So go there and learn about the relevant information and various offers.

Usually, most of these mistakes are made by tourists which is a waste of money and time. You must keep such mistakes in mind while traveling and avoid them properly.

Kalyan , Md and
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Habib Hasan posted in Travel Bangladesh

11 months ago

Tips to book a low-cost hotel for travel

On the trip, we are all more or less worried about the hotel. How will the hotel be or not! Also, because of the high cost of good hotels, many people have to stay in low-quality hotels at low cost. If the hotel is not available as you like, then the pleasure of travel seems to be reduced. So, let's know, about some ways to book a hotel at a low cost.

Book from hotel booking site:

Many times different hotel booking sites announce different offers or discounts. Through this offer, you can also find a low-cost hotel between two hotels with the same quality and facilities. You can consider those hotel ratings to understand good or bad hotels.

Most hotel booking sites have facilities to find low-cost hotels. So you can try to find low-cost hotels from hotel booking sites. Agoda, Booking.com, Trivago are among the most popular hotel booking sites.

Contact the hotel website directly:

If you are thinking of staying in a globally branded hotel, you can contact the website of those hotels directly. Usually, those hotels publish their offers on their own site. If you book directly in these hotels, you will get several benefits later.

For example, you will get loyalty points which will give you various benefits including discounts later on. That is why it is better to book these hotels directly by yourself than by any other medium.

negotiate with price:

Bargaining can reduce room costs. You can reduce the hotel room rent by bargaining by phone or by going directly to the hotel. Also in the off-season, you can get a room at a much lower cost.

Loyalty Rewards Program:

Different brands or mobile phone operators give loyalty points to their customers at different times. By accumulating these loyalty points you can get quite a good discount. Brands can use this loyalty program as travel deals. This will greatly reduce your hotel expenses on travel.

Using a bank card:

Many times different banks offer quite good discounts to their credit card customers during hotel bill payments. In a very luxurious hotel, you can halve the cost by paying with a bank card. So find out about such offers and try to use the card in bill payment.

Trying to buy someone else's reservation:

Sometimes it happens many people reserve hotel rooms but can't go for their business or various activities and they even cannot cancel the reservation. In such cases, many of them try to leave the reserve room at a low cost. So you can look for such offers from different sites and hotels. Try to accept any such offer. Your hotel costs will come down considerably.

Good quality and comfortable hotels are quite necessary to fully enjoy the trip. So follow the tips above and enjoy the trip better by reducing your hotel expenses.

Kalyan , Kaiser and
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