Gain insights into Docker fundamentals, delve into advanced concepts like database connectivity and Docker Compose, and discover how to monitor and scale services with Docker Swarm.

course_final_image.tar.gz

Flask App_new

docker-compose

Docker_build

flask_venv

Flask_demo_test

add db to container

Exercise

Exercise 2

exercise 3

exercise_4

Bonus Section - Flask

exercise 3-copy

docker-compose-copy

Docker_build-copy

add db to container-copy

Exercise 2-copy

exercise_4-copy

Bonus Section - Flask-copy

Docker_build-copy-copy

Whether you are a DevOps beginner or just a developer who wants to start working with containers, you’re in the right place. Docker is an in-demand technology that you will be exposed to frequently while on the job.

 

Docker is used for setting up, deploying, and running applications, at scale, by containerizing them. More on that later. Docker also provides developers with a consistent environment for product development, and along with Kubernetes, makes managing the development lifecycle a breeze.

 

In this course, you will learn the fundamentals of Docker such as containers, images, and commands. You’ll then progress to more advanced concepts like connecting to a database container and how to simplify workflows with Docker Compose. At the end, you’ll learn how to monitor clusters and scale Docker services with Swarm.

Working with Containers: Docker & Docker Compose

Let's start with the smallest component of Docker swarm which is Docker services.

# Initializing the swarm node
If you are using the Docker Desktop for Windows or for Mac, the Docker swarm comes prebuilt. You can check that using `docker swarm`. To initialize the swarm mode, type `docker swarm init`.

```
$ docker swarm init
Swarm initialized: current node (ayxwwpio1sksk5hi2bdqxanf4) is now a manager.

To add a worker to this swarm, run the following command:

    docker swarm join --token SWMTKN-1-19vn56bmfcc2l20jmts9gg9b152vkn47ruu6vtfwgsl3646ha2-8lcseq2vaegpjqytnnw1xgksn 192.168.65.3:2377

To add a manager to this swarm, run 'docker swarm join-token manager' and follow the instructions.
```

The node you started will be a manager node. We can add other machines or hosts to this swarm network using the command above with the provided token. But for now, we will see all the operations on a single worker-manager node only.

# Creating services

Like we have created containers using `docker run` command, a service does the same thing for a swarm cluster.

`docker service create <service name>` allows us to create a service on swarm with a defined number of containers in it.

Our aim is to create a load-balanced Flask app service and attach a database to it.

>Swarm cluster only works with prebuilt images. Hence, you need to first have the image of the app in order to create the services.

For this lesson, we will use the prebuilt image of our app. So, pull the image using the `docker pull venky8283/flask_app:3.0` command.

Now, let's create the first service, which is our Flask login app.

## Flask app

Type `docker service create --name web_app -p 5000:5000 venky8283/flask_app:3.0`. This will create a service with one container in it, which is also called a task.

```
$ docker service create --name web_app -p 5000:5000  venky8283/flask_app:3.0
image flask_app:3.0 could not be accessed on a registry to record
its digest. Each node will access flask_app:3.0 independently,
possibly leading to different nodes running different
versions of the image.

rnlrh4e262aew2c15ldz71c5k
overall progress: 1 out of 1 tasks
1/1: running   [==================================================>]
verify: Service converged
```

If the image is not pulled from the Docker Hub, it will warn us saying other swarm nodes may not have the same image, which is fine for now.

Getting Started with Docker Services

Introduction to Course

Why Docker?

Getting Started With Docker

Docker Fundamentals

Automation using Dockerfile

Advance Docker

Introduction to Docker-Compose

Exposure to Docker Swarm

Bonus Section

Getting Started with Docker Services

Initializing the swarm node