The document outlines deployment strategies and tools used in Kubernetes (k8s), focusing on concepts like replication, pod management, and deployment processes. It discusses various deployment strategies, including rolling updates, blue/green, and canary deployments, and emphasizes features such as upgrading, rollback, and scaling. Additionally, it contrasts deployments with statefulsets, which are better suited for stateful applications requiring unique identities and persistent storage.

1. Deployment Strategies & Tools

2. > whoami
- @abdennour
- Starting with k8s on AWS at 2017

3. > kubectl get agenda
- Intro
- Why Deployment ?
- What’s Deployment ?
- How Deployment?
- Deployment Strategies ( in general & in k8s )
- Deployment Features
- Demo ( distributed )

4. Intro

5. Intro – Lab Env for Demos
abdennour/sample-app:v1 abdennour/sample-app:v2 abdennour/sample-app:blue abdennour/sample-app:green
kubectl port-forward : access Pod from localhost

6. Intro – Horizontal Scaling & Replication
Pod Replication : Having many Pods with the
same definition (except "name”)
Replication Controller: maintain a stable set of
replica Pods running at any given time
ReplicaSet is the Replication Controller here
Name of Pods created by ReplicaSet follow this
format <replicaset-name>-<random-string>
3 ways to Scale out/in :
- change yaml, then kubectl apply
- Kubectl edit replicaset
- Kubectl scale replicaset .. –replicas X
Pod
Pod
Pod
Pod
ReplicaSet (app)
Desired=4, current=4
app-jmcgh
app-sgc25
app-xjfe2l
app-shxn4

7. Intro - Service
Always communicate with Pod thru Service
Pods are ephemeral in nature
k8s Service : Forward Traffic to Pod using
Lables & Selectors .
Service Forwards traffic to Pods
Service
Pod
Pod
Pod
Pod
Service
name=x,
namespace=app
Port=80
è http://x.app

8. Intro – Replication & Service Together
ReplicaSet replicates Pods with same Labels
Because all replicas has same labels, A service
with Selectors=Labels can forward traffic in
round-robin way.
è Service behaves like loadbalancer for
replicas ( pods With the same labels )
Service Forwards traffic to Pods
Service
Pod
Pod
Pod
Pod
ReplicaSet (app)
Desired=4, current=4

9. Why Deployment?

10. Why Deployment ?
Scenario:
You deployed an app few days ago.
Now you want to upgrade your app from v1 to v2.
Challenges:
● Can you upgrade with Zero downtime?
● Can you upgrade replicas sequentially one after another?
● Can you pause and resume upgrade process?
● Rollback upgrade to previous stable release

11. What’s Deployment ?

12. What’s Deployment ?
In General:
● Deployment is all of the activities that make a software system available for
use
● Deployment First Release vs Deployment Subsequent Releases
è First Installation vs Subsequent Upgrades
In Kubernetes:
● Deployment is automated using Controllers
○ Deployment controller
○ ReplicaSetController

13. What’s Deployment
Controllers for Pods Controllers Graph – Focus on Deployment

14. What’s Deployment
ReplicaSet : Pod Template + Replication
Deployment: ReplicaSet Template + Update Strategy
è Deployment : Pod Template + Replication + Deployment Strategy
è Name Of Pods Created by Deployment follow this format :
<deployment-name>-<replicaset-name>-<random-string>

15. How Deployment ?

16. How Deployment
Deployment Anatomy ‫ﺗ‬‫ﺸ‬‫ﺮ‬‫ﯾ‬‫ﺢ‬
- Replication
- Deployment Strategy
- Pod Template

17. Deployment Strategies

18. Deployment Strategies
● Recreate:
● Rolling Update (Ramped or
incremental)
● Rolling update with Additional
batch
● Blue/Green
● Canary
● A/B testing
Easy to Setup <> Expect Downtime

19. Deployment Strategies
● Recreate:
● Rolling Update (Ramped or
incremental)
● Rolling update with Additional
batch
● Blue/Green
● Canary
● A/B testing
Easy to Setup <> Rollout/Rollback take time

20. Deployment Strategies
● Recreate:
● Rolling Update (Ramped or
incremental)
● Rolling update with Additional
batch
● Blue/Green
● Canary
● A/B testing
Same as ROLLING UPDATE But :
- Increase number of replicas before
start the upgrade
e.g:
- v1 with 3 replicas
- Scale out from 3 to 5 replicas
- Start rolling update v2

21. Deployment Strategies
● Recreate:
● Rolling Update (Ramped or
incremental)
● Rolling update with Additional
batch
● Blue/Green
● Canary
● A/B testing
Instant Rollback <> Expensive

22. Deployment Strategies
● Recreate:
● Rolling Update (Ramped or
incremental)
● Rolling update with Additional
batch
● Blue/Green
● Canary
● A/B testing
Fast Rollback <> Slow Rollout

23. Deployment Strategies
● Recreate:
● Rolling Update (Ramped or
incremental)
● Rolling update with Additional
batch
● Blue/Green
● Canary
● A/B testing

24. Deployment Strategies with k8s Deployment
● Recreate
● Rolling Update (Ramped or
incremental)
● Rolling update with Additional
batch
● Blue/Green
● Canary
● A/B testing
- Create new Replica Set for v2
- Scale out new replica Set v2 to max
- Scale down existing replica set (v1) to 0

25. Deployment Strategies with k8s Deployment
● Recreate
● Rolling Update (Ramped or
incremental)
● Rolling update with Additional
batch
● Blue/Green
● Canary
● A/B testing
K8s gradually replaces existing pods in batches
- Create new Replica Set for v2
- Scale out new replica Set v2 gradually
- Scale in existing replica set v1 gradually
- Scale in existing replica set (v1) to 0

26. Deployment Strategies with k8s Deployment
● Recreate:
● Rolling Update (Ramped or
incremental)
● Rolling update with Additional
batch
● Blue/Green
● Canary
● A/B testing

27. Deployment Features

28. Features of Deployment
● Multiple Replicas
● Upgrade
● Rollback
● Scale Up or Down
● Pause & Resume

29. ‫ﺷ‬‫ﻜ‬‫ﺮ‬‫ا‬‫ﻋ‬‫ﻠ‬‫ﻰ‬‫ا‬‫ﻟ‬‫ﻤ‬‫ﺸ‬‫ﺎ‬‫ر‬‫ﻛ‬‫ﺔ‬‫و‬‫ا‬‫ﻟ‬‫ﻤ‬‫ﺘ‬‫ﺎ‬‫ﺑ‬‫ﻌ‬‫ﺔ‬

30. Appendix : Statefulset vs Deployment
•A StatefulSet is another Kubernetes controller that manages pods just like Deployments.
But it differs from a Deployment in that it is more suited for stateful apps.
•A stateful application requires pods with a unique identity (for example, hostname). One
pod should be able to reach other pods with well-defined names.
•For a StatefulSet to work, it needs a Headless Service. A Headless Service does not have
an IP address. Internally, it creates the necessary endpoints to expose pods with DNS
names. The StatefulSet definition includes a reference to the Headless Service, but you
have to create it separately.
•By nature, a StatefulSet needs persistent storage so that the hosted application saves its
state and data across restarts. Kubernetes provides Storage Classes, Persistent Volumes,
and Persistent Volume Claims to provide an abstraction layer above the cloud provider’s
storage-offering mechanism.
•Once the StatefulSet and the Headless Service are created, a pod can access another one
by name prefixed with the service name.