FitProgrammer@Work

Popular micro services patterns

noreply@blogger.com (rwatsh) — Sun, 24 Mar 2024 08:51:00 +0000

Here are some popular Microservice design patterns that a programmer should know:

Service Registry pattern provides a central location for services to register themselves.
Circuit Breaker allows your services to fail fast and prevent cascading failures, the circuit breaker pattern is used to isolate a failing service.
API Gateway provides a common entry point for all the requests and responses from the system. So, client only remember one host/port address rather than multiple IPs for each Microservice.
Event-Driven Architecture allows services to communicate with each other by emitting events.
In Database per Service each service has its own database, which allows services to operate independently.
Command Query Responsibility Segregation (CQRS) separates read and write requests for an application, allowing better scaling and performance.
Externalized Configuration allows storing configuration data outside of the application code, making it easier to manage configuration changes.
Saga Pattern manages the transaction forlong-running transactions that span multiple services.
Bulkhead Pattern isolates failures within a microservice, so a single failure does not bring down the entire system.
Backends for Frontends (BFF) design pattern provides a specific backend for each client. It allows the front-end team to develop features and add new client-specific functionality quickly.

Book Review: Spring Start Here: Learn what you need and learn it well

noreply@blogger.com (rwatsh) — Sat, 15 Apr 2023 12:00:00 +0000

Spring Start Here: Learn what you need and learn it well by Laurentiu Spilca
My rating: 5 of 5 stars

This is an excellent book on getting started with Spring boot based development. Written in a lucid manner and explained the fundamentals of spring ecosystem and some of the most important frameworks very well. This includes -Spring Core, data and test. Of course there is much more to be learned after this about other spring frameworks but with the concepts understood it will be much easier to do so. Read this before reading Craig Wall’s Spring in action book.

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Development Environment on Windows 11

noreply@blogger.com (rwatsh) — Sat, 25 Mar 2023 01:08:00 +0000

Recently i started using Windows 11 after spending a good amount of time on Ubuntu as my primary OS on my home laptop. There was no strong reason to move other than just wanted to see if i can build a better development environment on Windows than what i had on Ubuntu. To my pleasant surprise, Windows 11 with WSL Ubuntu brings the best of both worlds - a perfect functional and responsive desktop environment together with the powerful tools from the Ubuntu Linux for running docker, kubernetes cluster and anything else that one is used to on a Linux setup.

Found this article to be pretty useful in setting up WLS2 and install Docker and minikube in WSL2 on Windows 11 - https://www.virtualizationhowto.com/2021/11/install-minikube-in-wsl-2-with-kubectl-and-helm/ As you can note that no need to install docker desktop. The docker daemon run in WSL2 Ubuntu VM.

The article has all the steps outlined so no point in repeating it here. It will get all the required tools one needs to work with k8s.

To setup a development environment for doing ML with conda, python3, Jupyter notebook, tensorflow and VS Code:

1. Install conda environment and package manager - https://docs.conda.io/projects/conda/en/latest/user-guide/install/index.html

Used miniconda3.

conda init
conda create -n devpy python
conda activate devpy

Will create a virtual environment devpy and activates it.

2. Install Jupyter notebook

pip install notebook

3. Install TensorFlow and other ML related python libs

pip install --upgrade pip

pip install --ignore-installed --upgrade tensorflow matplotlib pandas sklearn scipy seaborn
jupyter notebook

4. Launch the notebook in the VS Code editor

VS Code terminal will launch Ubuntu. Also install the Python extension which will show the option to run the Jupyter notebook in the devpy virtual environment we created above.

See this article on how to use VS Code with WSL2 - Using WSL 2 with Visual Studio Code

To go to the location where WSL2 Ubuntu files are from Windows Explorer use path \\wsl$\ubuntu.

To go to the location where Windows files are in Ubuntu terminal use path /mnt/c/.

Book Review: Where the Crawdads Sing by Delia Owens

noreply@blogger.com (rwatsh) — Thu, 04 Aug 2022 05:17:00 +0000

Where the Crawdads Sing by Delia Owens
My rating: 5 of 5 stars

This is story of a girl who lives alone in the marsh land of North Carolina near a small town of Barkley Cove. Her parents and siblings leave home in her early childhood and she was left alone. She learns to read thanks to a friend and also becomes an author of several books related to birds and animals of marsh land. This book also has a mystery surrounding the death of a man where the marsh girl Kya becomes the suspect. The book has several poems and nice literary description of the marsh land. For those who love to read literature and are not looking for thriller or murder mystery book will enjoy this book very much.

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Favorite IntelliJ IDEA Plugins

noreply@blogger.com (rwatsh) — Sun, 10 Apr 2022 00:05:00 +0000

Some of my favorite IntelliJ IDEA plugins.

I am still waiting to get access to GiHub Copilot at this time.

Font = Monaco with Ligature enabled and size 14.

Theme = Xcode Dark

All of them work on IDEA Community edition.

FIRST Lego League Explore 2021-22 Season Cargo Connect

noreply@blogger.com (rwatsh) — Sun, 13 Mar 2022 06:57:00 +0000

Today my daughter's team completed their first season of FIRST Lego League Explore by attending the festival hosted at Meridian World school at Round Rock. Seen above is the team showcasing their poster board showing their team's journey through the season and the Cargo Delivery vehicle they built using the WeDo 2.0 kit and the Explore set parts based on the season's theme of Cargo connect. The challenge was to improve the cargo delivery and the team's solution was to make a delivery vehicle that can automatically stop when it senses (via a distance sensor) an obstacle in its path. This is how we could improve the delivery of the cargo by making the delivery vehicle safer to drive.

FIRST Tech Challenge 2022 Freight Frenzy - Our Robot

noreply@blogger.com (rwatsh) — Fri, 25 Feb 2022 09:48:00 +0000

Our final robot for this season shown above.

Other videos of the robot in the making can be seen in the team's playlist at - https://www.youtube.com/playlist?list=PL58XiTEgkLJ2IjdzKOBIgBuN_Q6N_j9Sw

Book Review: Speed Reading: Learn to Read a 200+ Page Book in 1 Hour by Kam Knight

noreply@blogger.com (rwatsh) — Mon, 27 Dec 2021 06:42:00 +0000

Speed Reading: Learn to Read a 200+ Page Book in 1 Hour by Kam Knight
My rating: 4 of 5 stars

Good tips on speed reading. Short and to the point book and we can practice what we learn right while reading the book. The habit of vocalization, visualization, spaced reading, peripheral vision and chunking will need to be practiced to be internalized. The last chapter on exercises for the eyes was great. Overall a great read.

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Book Review: Airframe by Michael Crichton

noreply@blogger.com (rwatsh) — Tue, 09 Nov 2021 14:17:00 +0000

Airframe by Michael Crichton
My rating: 3 of 5 stars

An American aircraft manufacturing company Norton, lands into trouble when one of its commercial airline customers Transpacific from China had a serious accident during flight which led to 4 deaths and several injuries. The company has a pending sales deal with China which they stand to loose if the bad reputation of their N-22 aircraft becomes a common knowledge. So they put their staff Cassey Singleton to figure out the actual reason why the accident happened. The company believed their aircraft was very well tested and finds it hard to believe that it could be a problem in the aircraft as the root cause for the accident. Finally Cassey gets to the bottom of the issue and saves the company from bad press. The story is simple and the writing is as expected great. A good read.

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FIRST Programs - FLL Explore and FTC 2021-22 are on!

noreply@blogger.com (rwatsh) — Thu, 05 Aug 2021 22:04:00 +0000

My family has been involved with FIRST related STEM programs from FLL to FTC for past couple years. It was for my son Rushil. And this year we have my younger one Aarini join in starting her first FIRST Lego League Explore season. It will be fun and i will be mentoring both their teams.

Here are the season teasers for 2021-22 season for,

FLL Explore:

FTC:

Book Review: The Sentence is Death (Hawthorne and Horowitz Mystery, #2) by Anthony Horowitz

noreply@blogger.com (rwatsh) — Thu, 05 Aug 2021 21:52:00 +0000

The Sentence is Death by Anthony Horowitz
My rating: 5 of 5 stars

This is second book in the Hawthorne and Horowitz series. The story is as exciting as the first one and very well told. Its written in the same vein as Sherlock holmes and Dr Watson where Ex-DI Hawthorne plays Sherlock and the author plays his biographer Dr Watson. The story starts with the murder of a divorce lawyer Richard Pryce. Hawthorne solves it in the end after having interviewed all persons involved with the dead lawyer in his last days. Waiting for the next one in the series - A Line to kill.

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FIRST Tech Challenge Season 2021 - Ultimate Goal

noreply@blogger.com (rwatsh) — Tue, 20 Jul 2021 03:45:00 +0000

We (the team Skyrise robotics) participated in the FIRST tech challenge 2020-21 season last year.

Following are some of the videos of the robot we made.

Travel: Road trip to Rocky Mountain National Park, Colorado

noreply@blogger.com (rwatsh) — Thu, 15 Jul 2021 17:20:00 +0000

This year we did a road trip to the Rocky Mountain National Park during the July 4th weekend.

Day 1 - We started from Austin on 2nd late afternoon and stopped over at Amarillo for the night.

Day 2 - At Amarillo, we saw the Cadillac ranch and kids did some spray painting. After that on the way in Trinidad Colorado we saw the Art cartopia.

Later that evening we reached Denver. We stayed at a hotel in the downtown which was walking distance from malls at 16th Street.

We walked to Union Amtrak Railway Station and took a free mall ride bus on our way back to the hotel. At the Union station we saw some ads for the upcoming MLB All stars baseball game. A huge baseball was at display right at the entrance of the Union station where we took some pictures.

Day 3 - We started on our way to Estes Park but first we went to see the Denver Botanic Gardens which was also located near downtown. On our way we saw the city capitol building as well. Denver Botatnic garden was pretty nice and took us some 2 hours to explore. We reached late afternoon at Estes Park where we stayed at walking distance from Lake Estes. Estes park is a small city and is very scenic with Rocky mountain views from wherever you stay. After dinner we walked in the city by the lake.

It was July 4th so shops closed early and we were back to the lake Estes and sat down near it for fireworks show at 9.30pm. It was a fun evening and a great fireworks show will lasted for 30 mins.

Day 4 - We went to the Rocky mountain national park at 8am. We parked at the Park and Ride stop and took the free shuttle to the Bear Lake corridor. There we hiked to the bear lake, nymph lake, dream and emerald lakes.

Then we decided to do a harder hike to the Bierstadt lake which was 2 miles up and then 2 miles down. The path was bit hard on the way up the hill but coming down was easy and very scenic. Kids had fun doing the hike. All the while i was worried about seeing some animal on the way as we were the only ones on the hike for the most part and will only get to meet few others at times. But fortunately we did not see any animals other than the marmots, squirrels and some mountain birds.

Day 5 - We saw the Stanley hotel where The Shinning movie was shot (and the book by author Stephen King is based on). Then we entered the park to take the Trailridge Road to Grand Lake. Trailridge road is very scenic and we used the Gypsy app to get a guided tour while we drove. We stopped at the Fall River trailhead and did some hiking then reached Grand Lake later afternoon. We had enough time to get a small fishing boat rental (from the Grand Lake Marina) for an hour and went boating on the Grand Lake. Grand Lake is much smaller than Estes park and shops close pretty early.

Day 6 - We started from Grand Lake to Colorado Springs. On the way we took the Georgetown Loop Railroad ride and their mine tour. It was educational and fun for kids. You do need to book the ticket in advance during peek season so do it before you make the trip there. Later that afternoon we arrived at Colorado Springs and went to see the Garden of the Gods.

Day 7 - Next day in Colorado Springs we visited Pikes Peak early morning. Driving up and down this high mountain was pretty scary but the views from the peak make it worthwhile. After pikes peak we went to see the Seven Falls. It took more time than we had expected. There is a long wait from parking to take the free shuttle and go to the seven falls and then a wait to come back to parking. But it was very scenic and worth all that waiting.

Day 8 - We visited the Royal Gorge Park and took the zipline ride there. Then at 3.30pm we took the lunch train ride at the Royal Gorge Railroad which was close by. The Royal Gorge has Arkansas River where we saw folks doing river rafting which seemed fun but we did not plan for it this time. Again you need to do the reservation in advance for it. We started on our way back to home the same day and made a stop at Lubbock city that night.

Day 9 - We arrived back home by evening.

We needed more time to do more hikes in the RMNP. There are so many trails suitable for all ages. Weather in summer time is great to visit the place. We packed winter clothes but never needed those. A light jacket and a poncho are needed for the hikes. It rained when we hiked and thankfully we did pack a poncho with us. They sell it there in the park too. Overall the road trip was very enjoyable, roads are in great condition and driving was safe and comfortable.

Please note: The pictures above were taken with Nikon D7100 with the default lens that comes with the camera and mostly in auto mode (as i have not yet tried learning the different non-auto options that the camera has). Some of the pictures can make a very good wallpaper (feel free to use it) and it is not because of my good photography but because the place is so beautiful that you just cannot go wrong. :)

Book Review: Graphic Classics: Journey to the Center of the Earth (Barron's Graphic Classics) by Fiona MacDonald, Penko Gelev, Jules Verne

noreply@blogger.com (rwatsh) — Wed, 26 May 2021 15:26:00 +0000

Graphic Classics: Journey to the Center of the Earth by Fiona MacDonald
My rating: 4 of 5 stars

Got this from our local library. It is a nicely done graphic novel that summarizes the story and also presents a short biography on the author Jules Vernes' life at the end of the book.

About the story - An archaeologist Prof. Lindenbrock and his nephew Alex together with a friend Hans embark on a journey to the center of the earth through the mouth of a dormant Volcano in Iceland. Professor believed that the earth is hollow and has a different world inside - they find an inland ocean, with monsters that were extinct on the earth's surface. They find long extinct giant trees and prehistoric men who are 13 feet tall. They kept going deeper and were eventually thrown out with a volcanic eruption on the surface of the earth. Jules Verne was one of the early science fiction writers and this story is one of his famous works together with Around the world in 80 days and 20 thousand leagues under the sea.

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Book Review: The Mysterious Affair at Styles (Hercule Poirot #1) by Agatha Christie

noreply@blogger.com (rwatsh) — Wed, 28 Apr 2021 15:02:00 +0000

The Mysterious Affair at Styles by Agatha Christie
My rating: 4 of 5 stars

My first Agatha Christie’s book.. the plot is thick and suspense is kept until the very end of the book. Now on to my next one of Monsieur Hercule Poirot’s mystery.

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Passed Certified Kubernetes Application Developer exam

noreply@blogger.com (rwatsh) — Mon, 19 Oct 2020 09:16:00 +0000

Wrote CKAD test on Sunday 10/18/20 at 11am. Exam has 19 questions of which I could attempt 17. I have been using kubernetes in oracle cloud for almost a year now and have been practicing for CKAD for some time so I think being able to attempt all 19 questions is difficult. Some questions required more time than others. I don't think there is equal weightage to all questions.

You can take the test from home. We can use an external monitor with the laptop (which i did) and we need to share both the laptop and the monitor's screen with the proctor. We also need to share the camera so proctor can watch while we take the test. The initial setup with PCI (test taking company) is bit involved and may take 15-20 mins so plan accordingly. In my case i could not write the test first time where the web terminal was unable to connect to Linux Foundation's server. Proctor tried with me for almost 1.5hrs and finally needed to reschedule. The next attempt was smooth but still setting up for the exam does take about 15mins.

At the beginning of each question you are given a command to connect to the right cluster. There were 4 such clusters. For the questions i attempted, only 2 of the 4 clusters were used. Also the questions are grouped together by the cluster you need to connect to in order to minimize the changing between clusters. Also there are parts in the question that can be clicked on and copied and then pasted in the terminal. The terminal is a web terminal so you can see it side-by-side with the question on the same web page. You can have one more tab open for https://kubernetes.io/docs. So it is an open book exam but speed really matters so you need to know what to look in the docs and where to look in it.

Grading of the exam may take up to 36 hrs after which the result of pass/fail is known.

I will update the post once i have the result.

I failed my first attempt - scored 60% and pass score is 66%.

I attempted my re-take today 10/25/20 (Sunday) at 11am CST. This time i realized that each question has a weightage mentioned in percentage. Like some were 2% whereas some were 7%. I also flagged 3 questions to come back to later and moved on. So by the time i was on 19th question i had 32 mins left. I did get sufficient time this way to at least look at all questions. Of the 3 i had marked to return back to later, i only could attempt 1 of them. But they each were 2% weightage so most likely my score wont be impacted by much. Lets see how i fair this time. I will update again tomorrow evening once i receive my result.

An easy to install local single node k8s cluster is microk8s from Ubuntu. I had used this and OLCNE clusters for my practice but microk8s is the easiest option.

Received result for my CKAD exam - i scored not too high (67% only) but still could clear the exam successfully. I plan to write CKA sometime down the line. I think to clear this exam one needs to be quick with typing linux commands. I think 80% or above is a very good score for this exam. But anyway now that i am past it i will rather focus on learning more at this point. Waiting for the Marko Luska's Kubernetes in Action 2nd Edition book to be published and in the meanwhile will be ramping up on other Cloud Native stuff - like service mesh, functions, API gateway, streaming services and monitoring stacks (ELK, Prometheus, Grafana) etc.

Following are the materials i used to prepare:

https://github.com/bmuschko/ckad-prep - to practice exercises with the below video course.
https://learning.oreilly.com/learning-paths/learning-path-certified/9781492061021 - Video course by Brian Muschko
https://kubernetes.io/docs/ - Must practice finding the yaml definitions by searching the docs for various tasks - like creating deployments, services, network policies, etc.
https://courses.edx.org/courses/course-v1:LinuxFoundationX+LFS158x+2T2019/course/ (Free) - This is required before you do the paid course from CNCF for CKAD.
Book: Kubernetes Up and Running 2nd Edition by Burns, Beda and Hightower - A more up-to-date book that covers all commands and a quick read compared to the next book.
Book: Kubernetes in Action by Marko Luska - This is a large book but very readable and said to be one of the best to understand the concepts behind the components of kubernetes.
CNCF CKAD Training course (Paid) - https://www.cncf.io/certification/training/
Exercises: https://github.com/dgkanatsios/CKAD-exercises - Must do set of exercises.
CKAD Prep Notes: https://github.com/twajr/ckad-prep-notes

My study notes on CKAD exam prep is available at https://www.amazon.com/dp/B08MXGDT3L

noreply@blogger.com (rwatsh) — Tue, 28 Jul 2020 00:42:00 +0000

The Cuckoo's Calling by Robert Galbraith
My rating: 5 of 5 stars

A great mystery series by the one and only J K Rowling or Robert Galbraith. This is the first book in the series of Cormoran Strike and his good assistant Ms Robin Ellacott. Robin has just moved to London city from country side and has joined temporary placements agency which places her to be assistant to one Mr Strike who is a private eye. Robin brings good luck to Strike as one her very first day there comes a client Mr John Bristow who wanted Strike's help in investigating the death of his sister Lula Landry, who was a supermodel and whose death was considered a suicide thus far. From there on Strike interviews all possible folks who came in contact with Lula in her daily life and finally he and Robin solve the mystery and find the killer. A nice whodunnit book by one of my favorite authors.

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Book Review: The Body: A Guide for Occupants by Bill Bryson

noreply@blogger.com (rwatsh) — Wed, 17 Jun 2020 13:32:00 +0000

The Body: A Guide for Occupants by Bill Bryson
My rating: 5 of 5 stars

This was my first book by Bill Bryson. He is an excellent author - the book is easy to read and thoroughly researched. In this book author makes the subject of human body accessible to laymen. My interest in this book was to get a refresher of things i had read in biology classes in school days and topics that one hears being mentioned by health related books/articles - ranging from understanding of how the different organs, glands and parts of the body function, the different kinds of diseases, their symptoms and how they are acquired, our body's built-in defense mechanism (the immune system, white blood cells and the different glands that fight-off the harmful microbes entering our body - like the placenta that shields the womb/baby from the harmful microbes), aging and eventually death and the state of the body after one dies. It also mentions of the evolution of medical science to some extent and calls out the people who contributed to the field - sometimes at the cost of their own lives. A very interesting read.

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Book Review: The Picture of Dorian Gray by Oscar Wilde

noreply@blogger.com (rwatsh) — Wed, 03 Jun 2020 03:07:00 +0000

The Picture of Dorian Gray by Oscar Wilde
My rating: 4 of 5 stars

I had been meaning to read this book for a long time and finally could get this checked off the list of to-be read books. The impression i had of this book was that it will be a quick read but as is the case with every book that is heavy on literature, it tends to be a dense read -as most of the book is loaded with phrases and full of sentences that can be underlined and quoted. The story is short - a guy named Dorian Gray is blessed with good looks and full of youth. Dorian sits for a painter Basil Hallward, who worships Dorian and considers Dorian to have a very positive influence on his art - one that any artist can only find by chance in their life time. Then there is Lord Henry Wotton who is a friend of Basil and Dorian. Dorian learns from Lord Henry the importance of youth and comes to see his own portrait painted by Basil full of life. Basil gives that painting to Dorian to keep. Dorian likes that painting so much that he wishes if only he could never loose his youth and his painting becomes old with time instead. This wish of his comes true. As time passes Dorian retains that charm of his youth, the same boyish look he had when he sat for that painting. The painting instead starts to appear old. As Dorian gets drawn towards vices in his life he is still able to retain his youth but his painting started to show the evil look. Dorian hides the painting from everyone. He commits several sinful acts and evens kills the painter who drew the picture. At the end he decides to kills the Dorian in the painting and that puts an end to his life.
It is not a light reading as i had thought initially so read it if you enjoy reading good literature (prose or poetry).

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Book Review: The Eye of the Needle by Ken Follet

noreply@blogger.com (rwatsh) — Mon, 25 May 2020 01:36:00 +0000

Eye of the Needle by Ken Follett
My rating: 5 of 5 stars

A german spy Die Nadel (or The Needle) has been in London during World War II. He is assigned the task to gauge the military at Port Calais in France. Allied forces have been planning a camouflage setup at Calais to dupe the Germans into thinking the attack is going to happen from Calais instead of from Normandy. To that effect, many artists and movie studio setup workers were put to building a massive fake military setup in Calais. Die Nadel or Henreich Faber happens to find out that its a fake and not a real military setup and from that point on the book is about whether he is able to deliver the proof of his findings to Abwehr in time or not. The story is fast paced and keeps the reader engaged. A good novel to start reading the works of Ken Follet.

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Book Review: The Death of Ivan Ilych by Leo Tolstoy

noreply@blogger.com (rwatsh) — Sat, 09 May 2020 02:57:00 +0000

The Death of Ivan Ilych by Leo Tolstoy
My rating: 5 of 5 stars

This is the first book of Leo Tolstoy i read. Its a small novel with 10 chapters and took me about 3hrs to complete in all. The story is about the life of a man named Ivan Ilych. It starts with folks from his work and his friends attending his funeral. The story then revolves around who he was and how he got injured on falling while he was infatuated with decorating his new house, his relationship with each member of his family, his reminiscences during his last days of his life when he reflects on his childhood and the happy memories of those days, what he feels about the doctors who don't seem to empathize with him and fail to answer his questions concerning his health in a direct manner. Tolstoy excels in describing the emotions of the characters and there are several occasions when the reader feels drawn by the realism of author's description of what the characters feel. Its a masterpiece of a work and i highly recommend it for the literary value of this book if not so much for the story in it.

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Passed Docker Certified Associate Exam

noreply@blogger.com (rwatsh) — Wed, 06 May 2020 00:11:00 +0000

Passed Docker Certified Associate exam today May 5th 2020.
I have been procrastinating on this for a while but due to COVID-19 shelter-in-home and no classes to take kids to, got enough time to get this taken care of.

Now regarding the exam, while i was lingering on when to take this exam (had enrolled last year December) Docker got bought by Mirantis and the DCA exam which used to multiple choice only became a bit harder with majority of questions (42 of total 55) being DOMC (Discrete option multiple choice). Also the syllabus got revised (v1.1 of study guide) to include many Kubernetes topics in the exam. Lots of Kubernetes related questions were there from topics including persistent volumes, configMaps etc. Fortunately i am also preparing for CKAD (Certified Kubernetes Application Developer) and going to write it soon on 16th May, 2020 so i was able to answer those.

My study notes are available at https://www.amazon.com/dp/B08MY87SMK

My experience taking the test was - it took me about an hour to complete the exam so i think the 90mins duration is sufficient.

Setup a k8s cluster with OLCNE

noreply@blogger.com (rwatsh) — Mon, 04 May 2020 14:15:00 +0000

To install a development setup for kubernetes an easy option is to use https://github.com/oracle/vagrant-boxes/tree/master/OLCNE.

All we need is virtualbox and vagrant installation, clone the above git repo and run vagrant up.

By default it creates a k8s cluster with 1 master and 2 worker nodes.

As of today it installs OEL 7.8 with k8s 1.17.4.

[vagrant@master1 ~]$ kubectl get no
NAME STATUS ROLES AGE VERSION
master1.vagrant.vm Ready master 3h35m v1.17.4+1.0.1.el7
worker1.vagrant.vm Ready 3h34m v1.17.4+1.0.1.el7
worker2.vagrant.vm Ready 3h34m v1.17.4+1.0.1.el7
[vagrant@master1 ~]$ cat /etc/oracle-release
Oracle Linux Server release 7.8

Setting up VSCode for Go Programming

noreply@blogger.com (rwatsh) — Mon, 27 Apr 2020 07:40:00 +0000

Idea behind Golang is to minimize the number of lines of code.
Primary use of Go is to write server-side programs or command line programs.
Creators of Golang - Ken Thomson, Rob Pike and Robert Griesemer
Modern standard library
Compile to single native binary - no runtime required.
Has garbage collection built in
Simple, strongly-typed, procedural language with object oriented features - very few language features have been added since 1.0 release
Built-in concurrency
Fast to compile and run quickly
Some popular Go projects:

K8s
Docker
Prometheus

To setup an IDE for Go - Visual Studio Code is a good choice.

Install VS Code from https://code.visualstudio.com/download
Setup VS Code for Go development by installing the “Go” Extension from Microsoft
Also install the Go packages by:
Cntl + Shift+ P or View > Command Pallet
Enter: Go: Install/Update Tools
Select All and Click OK.
Go to Settings for Go Extensions - Look up “Infer GoPath” setting and enable/check it.

Now you should be able to use the IDE to edit and compile/run go code.

Also watch this screencast https://www.youtube.com/watch?v=XCsL89YtqCs on writing, building, installing and testing Go code.

Set GOPATH environment variable to a directory where your go code will reside.

For example: ~/go directory.

export GOPATH=~/go

Under ~/go create 3 directories that go requires:

src, pkg and bin

At any point look for the go documentation as:

> go doc fmt.Println

Following is a hello world program that will go in ~/go/src directory.

package main

import "fmt"

func main() {

fmt.Println("Hello, World")

}

In VS Code launch the Terminal (Cntl + Shift + `) or Terminal > New Terminal.

To build the program:

> go build hello.go

> ./hello

To directly run the program and not build it first:

> go run hello.go

Creating a docker swarm cluster with virtualbox

noreply@blogger.com (rwatsh) — Tue, 21 Apr 2020 11:16:00 +0000

On the host system:

1. Install virtualbox:
sudo apt install virtualbox

2. Install docker:
sudo apt install docker.io

Add user to docker group:
sudo groupadd docker
sudo usermod -aG docker $USER

Either manually create 3 VMs (1 manager and 2 workers) or use docker-machine.

Note: With Secure UEFI boot enabled in BIOS installation of virtualbox requires us to generate a MOD key protected by password. When installation completes we are required to reboot and then enroll the MOD key by entering the same passphrase for the key.

Approach 1 - Manually create 3 VMs (1 manager and 2 workers) - Recommended
Networking for the 3 VMs should meet the following requirements:
1. We should be able to ssh to each of the ubuntu VMs from host system.
2. We should be able to access internet from ubuntu VMs. This is required for the docker registry access.
3. Lastly, each VM should be able to reach the IP address of other nodes in the cluster.

If installing ubuntu VMs also install docker -- this can be selected during OS install .. but you will still need to add your user to docker group post installation.

To setup networking for the VMs:

1. Virtual Box > Host Network Manager > create an adapter (it will be named vboxnet0 by default) say with the following config:
DHCP - Enabled (though this is not best way but generally the IP allocated to a VM wont change and it saves the effort of manually configuring the static ips on each VM)

Refer - https://www.tecmint.com/network-between-guest-vm-and-host-virtualbox/

Configure Adapter Manually :
IPv4 address: 192.168.56.1 -- this becomes the gateway address
IPv4 Network Mask: 255.255.255.0
Leave the IPv6 settings to default

On DHCP tab:
Server Address: 192.168.56.100 -- the DHCP server
Server Mask: 255.255.255.0
Lower Address Bound: 192.168.56.101 -- first VM's ip address can begin with this.
Upper Address Bound: 192.168.56.254

2. Select each ubuntu VM > Settings > Network > create 2 Network Adapters.
Network Adapter 1 ->

Check the option: “Enable Network Adapter” to turn it on.
In the field Attached to: select Host-only Adapter
Then select the Name of the network: vboxnet0

Network Adapter 2:

Check the option: “Enable Network Adapter” to activate it.
In the field Attached to: select NAT

For ease of being able to ssh to VMs by name:
Add the following entries to /etc/hosts (change to your preferred names) on the host system:

192.168.56.101 manager
192.168.56.102 worker1
192.168.56.103 worker2

Also to enable ssh without password:

create ~/.ssh directory and a file under it called authorized_keys

mkdir -p ~/.ssh

echo "[public key]" >> ~/.ssh/authorized_keys

Now you can ssh to the VMs without having to type in the password. For e.g.:

ssh [user]@manager

Once on the VM, try doing nslookup www.google.com and verify the internet connection is working.

Also verify you are able to ping the other 2 node ips.

Approach 2 - Use docker-machine
To create via docker-machine use the command though i prefer the above approach as it gives more flexibility to choose our preferred OS version to install instead of having to live with the version that comes with docker-machine. Also with docker machine approach you end up running one additional VM which runs docker. On a Linux host we dont need that as docker engine can run natively on the host system rather than requiring a separate docker host VM.

docker-machine create -d virtualbox default

The above command will create a VM with name "default" that will be used as host for running the docker engine and additionally will create 3 nodes for swarm cluster.

To Setup Swarm mode:
On Manager node:

$ docker swarm init --advertise-addr 192.168.56.101:2377 --listen-addr 192.168.56.101:237

where, 192.168.56.101 is this manager node's ip address.

We only have one manager which also is the leader. Docker swarm supports having more than one manager nodes but there can be only one leader among them at any given time. We run the swarm init command on the leader node and all other manager nodes will then join the swarm cluster using the manager token.

On 2 Workers:
Run swarm join command for worker nodes to join the swarm cluster.

$ docker swarm join --token SWMTKN-1-4azauf7ujxp711zzwb1ihfluqjy5om6pa4zlicmm7pq3l0svcp-d2bgy5mtsl0w82n99suvb1uu6 192.168.56.101:2377 --advertise-addr 192.168.56.102:2377 --listen-addr 192.168.56.102:2377

The above command will be given in o/p of swarm init.

To get the above commands again anytime following commands can be used on the manager node to get it:

docker swarm join-token manager
docker swarm join-token worker

Running docker info will show there is 1 manager and 3 nodes in swarm cluster and that swarm is active. It will also show if the current node is a manager or not.

To deploy a test app (an example from nigel poulton's course on pluralsight.com).
docker service create --name psight1 -p 8080:8080 --replicas 5 nigelpoulton/pluralsight-docker-ci

docker service ps psight1

The above command will show which node is each replica running on.

$ docker service ps psight1

ID NAME IMAGE NODE DESIRED STATE CURRENT STATE ERROR PORTS
jk55y1btc0mo psight1.1 nigelpoulton/pluralsight-docker-ci:latest worker2 Running Running 40 seconds ago
3tlq4zb5s78m psight1.2 nigelpoulton/pluralsight-docker-ci:latest worker1 Running Running 40 seconds ago
tonkv7bmjei5 psight1.3 nigelpoulton/pluralsight-docker-ci:latest worker2 Running Running 41 seconds ago
znoek7dwq6x5 psight1.4 nigelpoulton/pluralsight-docker-ci:latest manager Running Running 41 seconds ago
teg2amzw2f73 psight1.5 nigelpoulton/pluralsight-docker-ci:latest worker1 Running Running 40 seconds ago

That's it! Now we have a working swarm cluster that we can use to deploy apps on.