Devops with Docker and K8S + django example

DEVOPS WITH
DOCKER AND
KUBERNETES
SOA presentation
1
2024-2025

Deploying a Django Application
Introduction to DevOps
01
Understanding Docker
02
Introduction to Kubernetes
03
Benefits of Docker and Kubernetes in
DevOps
Conclusion
04
05
06
Table of
Table of
contents
contents
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Why DevOps is revolutionizing software development ?

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Who Introduced DevOps and When?
Patrick Debois DevOpsDays conference
the "Father of DevOps” 2009

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Devops is not a technology, tool or framework .
DevOps is a cultural movement, mindset, philosophy to coordiante produce better, more reliable products.
by automating infrastructure, workflow, and continuously measuring application performance
for which they use a lot of tools.

10
The DEVOPS lifecycle :
You can visualize a Devops process as an infinite
loop, comprising the illustrated steps through
feedback --plan , which resets the loop.

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What is Docker ?
1.
Docker is a powerful platform that
simplifies the process of building,
shipping, and running applications.

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Solomon Hykes
1.1 - History of docker :

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1.2 - VMs Containers :

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1.3 - Docker Architecture :

16
1.4 - The Process of Creating Containers

Definition: Scripts used to create Docker images.
Purpose: Automates and ensures repeatable, consistent
image creation.
Structure: A text file containing a series of commands
that Docker uses to assemble an image
2. DockerFile :
17

3. Docker image :
These are the blueprints of applications.
A Docker image is a lightweight, standalone, and
executable package that includes everything needed to
run a piece of software .
Images are immutable, meaning once they’re created,
they don’t change.
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Docker image Registries
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4. Docker container :
A Docker container is like that lunchbox
self-sufficient and portable.
Imagine you have a lunchbox that contains
everything you need for a meal.
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Toss it, and it leaves no mess. Stop the container, and it leaves no
mess.
Multiple containers on a host
Multiple lunchboxes in your
backpack.
You can have
When you're done
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Docker containers are runnable instances of Docker images.
They encapsulate the application and its dependencies, providing
an isolated environment for execution.
Containers can be created, started, stopped, moved, and deleted
using Docker commands.
4. Docker container :
So, what’s a docker container ?
22

5. Docker compose :
23

Docker Compose is a tool for defining and running
multi-container Docker applications.
It uses a YAML file (docker-compose.yml) to
specify services, networks, volumes, and other
configurations required for the application.
5. Docker compose :
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6. Docker Volumes:

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7. Docker Networking:

Docker Hub is a cloud-based repository service
provided by Docker for storing and sharing Docker
images.
It serves as a central hub for the Docker community,
offering access to thousands of public images and
enabling collaboration among developers and
operations teams.
8. DOCKER HUB :
27

Before Docker Hub
Lack of
Standardization
No Centralized
Storage
Collaboration
Barriers
Limited
Automation
Quality Control
Issues
8. DOCKER HUB :
28

Searching for Images:
Use the docker search command to search for images on Docker Hub:
Pulling Images:
Pull Docker images from Docker Hub using the docker pull command:
Pushing Images:
Push local Docker images to Docker Hub using the docker push command :
8. DOCKER HUB :
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What is Kubernetes ?
1.
Kubernetes, or K8s, is an open-
source platform designed to
automate the deployment,
management, and scaling of
containerized applications.

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Created by Google, now maintained by the Cloud Native Computing
Foundation (CNCF).
Kubernetes is tailored for modern, container-based environments, such as
those orchestrated with Docker
2014
2015

34
2.Kubernetes Architecture

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What is a Cluster ?
A group of computers (physical or
virtual) that work together as a
system.
In Kubernetes, the cluster consists of:
A Control Plane (the brain of
Kubernetes).
Worker Nodes (the machines where
applications run).

The Control Plane is responsible for managing the
cluster, maintaining its desired state, and scheduling
workloads. It includes:
API Server:
Acts as the entry point for all administrative tasks. It
handles communication between the user (via CLI or UI)
and the cluster.
A - Kubernetes Master (Control Plane) :
36

Scheduler:
Decides which worker node will run a given pod based on
resource availability.
Controller Manager:
Ensures the desired state of the cluster by managing
controllers, like replicating pods or handling node
failures.
etcd:
A key-value store that holds the cluster's configuration
and state. It's critical for cluster consistency.
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A - Kubernetes Master (Control Plane) :

These are the machines where your applications
actually run. Each worker node has:
Pods:
A pod is the smallest unit in Kubernetes. It runs
one or more containers.
Example: If you're running a web server, it will
be inside a pod.
B - Worker Nodes :
38

Kubelet:
The guardian of the node. It ensures that the
pod is healthy and running properly.
Kube-proxy:
Manages communication between different
parts of the cluster and the outside world.
Container Runtime (e.g., Docker):
This is the tool that runs the actual containers.
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B - Worker Nodes :

3. Kubernetes YAML File Overview
A Kubernetes YAML file is used to
define resources and their
configurations in a Kubernetes cluster.
It is written in YAML syntax and is
structured with key-value pairs.
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A - Key Sections in a Kubernetes YAML File:
apiVersion
Specifies the API version of the
Kubernetes resource.
Example: apps/v1, v1.
metadata
Contains metadata about the
resource.
spec
The main configuration of the
resource, varying by resource
type.

B - Communication Flow :
42

C - Example: Deploying a Django Web Application :
The API Server processes your deployment request via kubectl.
The Scheduler assigns your Django app to a worker node.
The Kubelet ensures the app container runs properly in a pod.
43

Liveness and readiness probes are checks that Kubernetes performs on your
pods to determine their health.
Liveness probes check if your application is still running, while readiness
probes check if your application is ready to receive traffic.
4. Kubernetes Probes ?
So you’ve built an amazing app and deployed it to
Kubernetes .
That’s where liveness and readiness probes come in.
But how do you make sure your app stays up and running as
intended?
44

Liveness probes check if your application is up and running.
They ensure that if a pod goes down for any reason,
Kubernetes can restart it and get your app back online.
There are three types of liveness probes:
1. HTTP probe: checks for a successful HTTP response
(status code 200–399). This is good for web apps and REST
APIs.
2. TCP probe: Checks if a TCP port is open. Use this for non-
HTTP apps.
3. Exec probe: Executes a command inside the container.
Checks the exit code to determine health.
A- Liveness Probes
46

Readiness probes check if your application pods are
ready to accept traffic.
If a readiness probe fails, Kubernetes will remove the
pod from service load balancers and endpoints.
This ensures that clients don’t access pods that are not
ready to handle requests.
Some examples of readiness probes include:
Checking if a web server returns a 200 OK response
on a certain endpoint
Seeing if a database connection can be established
B- Readiness Probes
47

A Dockerfile was created to containerize the
Django application :
Uses the Python 3.10 image.
Installs the dependencies specified in
requirements.txt.
Copies the project into the container and
exposes port 8000.
Configures the Django server startup to run
the application.
Deploying a Django Application with Docker and K8S
49
Dockerfile_Django

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The docker-compose.yml file was created to orchestrate
the Django application with PostgreSQL :
Django Service : Based on the created Dockerfile, it
runs the web application, uses the volume named app
for storing necessary data, and is integrated into the
Docker network.
PostgreSQL Service : Uses the official PostgreSQL
image, with environment variables defining the
database parameters (user, password, name). It uses
the volume named db_data to ensure data
persistence.
docker-compose.yml

51
The command “docker-compose up --build” uses the Docker Compose tool to build the Docker image
specified in the Docker Compose file, then start the containers defined in it. The “--build” flag ensures
the latest changes are incorporated before starting the containers.

Devops with Docker and K8S + django example

53
This screenshot shows the process of building a Docker image from a Dockerfile for a Django application:
The docker build command is run to build the image using a file named Dockerfile_Django.
Steps Shown:
Docker pulls the base Python image,
Copies the necessary files,
Installs dependencies using pip,
And creates the final image.

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A namespace.yaml file was created
to define a namespace in
Kubernetes.
This namespace is named devops
and is used to organize and isolate
resources within the Kubernetes
cluster.
namespace.yaml

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A db-deployment.yaml file was created to configure a
PostgreSQL deployment within Kubernetes :
Specification Details:
Replicas: Configured with a single replica.
Selector: Applies a selector with the label app:
postgres to match the deployment.
Pod Template: The template specifies a
PostgreSQL container.
Container Configuration:
Image: Uses the postgres:latest Docker image for
the container.
Port: Exposes port 5432 for database connections.
Environment Variables:
POSTGRES_USER: Set to "postgres".
POSTGRES_PASSWORD: Set to "postgres".
POSTGRES_DB: Set to "django_db".
db-deployement.yaml

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A db-service.yaml file was created to configure a
Kubernetes service for a PostgreSQL database
Port Configuration:
Exposes Port: Exposes port 5432.
Redirects Port: Redirects port 5432 to the
target container port.
Selector: Matches pods labeled with app: postgres.
db-service.yaml

A File “django-deployment.yaml” was created to deploy a
Django application on Kubernetes :
Container Configuration:
Image: Uses ‘rami2708/devops-web’ image.
Port: Exposes port ‘8000’.
Environment Variables:
Configurations for PostgreSQL database
(username, password, database name, and host).
django-deployment.yaml
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A django-service.yaml file was created to configure
a LoadBalancer service for the Django application :
Port Configuration:
Exposes Port: Exposes port 8000.
Redirects Port: Redirects port 8000 to the
target container port.
Selector: Matches pods labeled with app:
django.
django-service.yaml

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Two pods are running:
pod/django-74cbf6cbbd-zg7xh
pod/postgres-7c77f684d7c-pm9j.
Two services are created:
service/db with a
ClusterIP
service/django with a
LoadBalancer.
Two deployments are running:
deployment.apps/django
deployment.apps/postgres
Two ReplicaSets are running:
replicaset.apps/django-74cbf6cbbd
replicaset.apps/postgres-7c77f684d7c.

Benefits of using Docker
Benefits of using Docker
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Benefits of using Kubernetes
Benefits of using Kubernetes
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Conclusion
Conclusion
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Using Docker and Kubernetes for Django app
deployment ensures scalability, consistency, and
efficiency. These tools modernize workflows,
making applications reliable and adaptable to
change.

Refrences
Refrences
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https://devopscube.com/build-docker-image/
https://www.linkedin.com/posts/hasibulislamnirob_what-is-devops-pdf-activity-7132398073485410304-jDb1?
utm_source=share&utm_medium=member_desktop
https://cloud.google.com/blog/products/containers-kubernetes/kubernetes-best-practices-setting-
up-health-checks-with-readiness-and-liveness-probes?hl=entext
www.clickittech.com
https://www.clickittech.com/devops/kubernetes-architecture-diagram/

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THANK YOU FOR YOUR
ATTENTION

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User Interface (UI) or CLI (kubectl) is used to send commands to the API Server.
The Scheduler allocates pods to specific nodes.
The Controller Manager maintains the cluster’s state.
Pods are created on worker nodes, and Kubelet ensures they run smoothly.
Kube-proxy manages network traffic between pods and services.
B - Communication Flow :

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