Forem: Bolton

How to run an Application using Docker Swarm

Bolton — Sun, 17 May 2020 09:53:53 +0000

What is Docker Swarm?

An Orchestration tool. An Orchestrator is basically a tool that helps you manage, scale, and maintain your containerized applications.
In other words, this tool helps in scaling your application, automating its maintenance, replacing failed containers automatically, and rolling out updates. Other examples of this tool are Kubernetes and Apache Mesos.

In this article, I will take you through managing and controlling multiple docker containers as a single service.

What you'll need:

Install Docker
Install Docker machine
Install Virtual box. we'll use this to create docker machines.

> sudo apt-get install Virtualbox

or on Mac

> brew cask install virtualbox

1. Create 3 docker-machines

Create a docker-machine called manager which will act as the manager.

> docker-machine create --driver virtualbox manager

The next step would be to create 2 more machines which will act as worker machines by running

> docker-machine create --driver virtualbox worker1

> docker-machine create --driver virtualbox worker2

You can check all the machines by running:

> docker-machine ls

You can now connect to any of the machines by running:

> docker-machine ssh manager

2. Create a Swarm

To create a swarm, ssh into the machine which will act as the manager (machine named manager in our case) and run:

> docker swarm init --advertise-addr MANAGER_IP

To get the manager IP, run:

> docker-machine ip manager

The next step would be to add the two worker machines to the Swarm we've just created.
While on the manager run the command below to get the actual command to use.

docker swarm join-token manager

Copy the generated code and ssh into each of the worker machines to join them.

While on the manager machine, run this command to see the created nodes

docker node ls

As shown above, you can see we have 3 nodes and the machine named manager as the Leader.

3. Running the application

In the manager machine, we are going to run three replicas of the application by running:

docker service create --replicas 3 -p 80:80 --name serviceName dockerImage

serviceName is the name of our application and you can use any Docker image you have. In this instance, I'm going to use Nginx.

To see the service we've created, run

docker service ls

To List the tasks under a particular service run:

docker service ps serviceName

3. Test the application

Copy the Ip of one of the docker machines and you'll see the Nginx service running.

Other commands

Display detailed information on one or more services

docker service inspect serviceName
Fetch the logs of service or task

docker service logs serviceName
Remove a service

docker service rm serviceName
Scale one or multiple replicated services

docker service scale serviceName=2

And that's all folks. Thank you for reading through. If this article was helpful, feel free to share it.

Happy Coding! 💚

Between Flutter and React Native, which one should I learn?

Bolton — Wed, 04 Mar 2020 09:10:57 +0000

I use React to build web apps but I want to learn about mobile development. I'm not sure which approach to take. Flutter or React Native?

The Power of Waking Up at 4:00 AM

Bolton — Tue, 09 Jul 2019 06:46:53 +0000

Have you ever wondered how waking up at 4 am feels like? if not, it's about time you actually do.
Just a few months ago, I had no idea how it felt. I had this habit of always hitting the snooze button or pretending not to hear the loud and annoying alarm.

Then one day I decide to wake up and I was able to hit the gym, do a little bit of coding and go to work on time. That's when it dawned to me and I realized what I've been missing out on. I did that for a week (5 days) and the things I was able to achieve (learn new programming concepts) in a day were pretty amazing.

I'm not alone in this. You find yourself setting the alarm the previous night only to hit the snooze button and feel sorry for yourself the rest of the day. The interesting bit is that you don't go to bed till 4 am chilling with Netflix.
Take a stand and decide you ain't gonna be a whiner and awaken the beast inside you. Try to wake up early before the rest of the world and see the magic of how productive you could be.

Not everybody can be a morning person but if it fails on your side at least adjust your schedule to get on or off your bed by reducing the amount of time spent sleeping. If 4, 5 or 6 am is too much to handle, restructure the pattern to probably sleeping late and waking up later in the day. Regardless of the choice you make (no one cares what time you do it), it's very important you get enough sleep (at least 6.5 hours) to avoid constant burnouts. So get to know your body, have a plan and create that time accordingly.

If you want to be proficient in that language you love then create the time you need. If you want to build and deploy that app so badly with your busy schedule then time is what you need. Take responsibility for your life and think about what you can achieve in those 2 to 3 extra hours. In case you claim you don't have enough time during the day, what are you doing to create more time? think about it, no one was given more than 24 hours in a day including yourself. It's only a matter of sacrifice to get more time.
We all have equal opportunities, the difference is how we get to utilize and act on them.

You have a plan tomorrow, something to achieve, someone to love, something significant to look forward to? then get up early or create extra time in whichever way you see fit!!!.
Everybody has problems, so deal with it. Do you want to have a feel of that freedom? Stop complaining and have a little bit of discipline. The sad truth is that if you do what is easy, your life will most probably be hard, but if you do the hard stuff, you have a chance of having an easy life.
Your future simply depends on what you do TODAY!!, so make it count.

Ask yourself what I heard someone asking, "What are you missing out for sleeping in? Everything. What are you gaining for sleeping in? Nothing. What are you giving up by sleeping in? Everything. What are you accomplishing by sleeping in? Nothing."
Just for one day, challenge yourself by creating extra hours IF YOU CAN at any time you desire. I'm NOT saying you sleep for 2 hours, that's a death sentence. Do that for a week (5 days) even if it's just an hour, and you're going to have something special.

Patterns of repetition govern each day, week, year, and lifetime. 'Personal habits' is one term we use to describe the most common of these repeated patterns. But I say these habits are sacred because they give deliberate structure to our lives. Structure gives us a sense of security. And that sense of security is the ground of meaning (Robert Fulghum).

Again, regardless of the pattern you choose, keep in mind that sleep is important. Have just the right amount of sleep since the best bridge between despair and hope is a good night’s sleep

And just as a reminder, someone great said, "Excuses sound best to the person that's making 'em up!"