OpenShift is a platform that helps developers build and deploy containerized applications. It provides core concepts like images, containers, pods, services and routes to run applications. Developers can build images using different strategies and deploy them to OpenShift. Persistent storage is used to persist application data across deployments. Developers can debug applications using remote shells or health checks. OpenShift supports different deployment strategies like rolling deployments, blue-green deployments and A/B testing to manage application lifecycles.

1. BASLE BERN BRUGG DÜSSELDORF FRANKFURT A.M. FREIBURG I.BR. GENEVA
HAMBURG COPENHAGEN LAUSANNE MUNICH STUTTGART VIENNA ZURICH
OpenShift for Developers
An Introduction
Sebastian Steiner
@sebisteiner

2. Sebastian Steiner
OpenShift for Developers2 9/25/2018
Senior Consultant
Project Service Delivery Bern (BE-PSD)
Working for Trivadis since 2010
Full Stack Java Developer
Current Project: «Sanierung Vertriebssysteme» at SBB
– Lead developer Webshop (https://www.sbb.ch/de/kaufen)
– Developer «Zentrales Vertriebssystem»

3. Agenda
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1. What is OpenShift
2. Running & Accessing OpenShift
3. Building & Deploying an Image
4. Persistent Storage
5. Problem Analysis
6. Application Lifecycle Management

4. OpenShift for Developers4 25.09.2018
What is OpenShift

5. What is OpenShift
OpenShift for Developers5 9/25/2018
A platform (PaaS) helping you to develop and deploy applications.
These can be web applications, backend applications or databases.
Any programming language is supported.
The application must be runnable in a container.
Source:http://www.dilbert.com/strip/2015-04-08

6. An Image is a binary that includes everything for running a single container.
A Container is a running instance of an image.
A Pod is one or more containers deployed together on one host.
A Service identifies a set of replicated pods.
A Route exposes a service to the outside world.
A Project scopes resources in a cluster.
A Build transforms input parameters or source code into a runnable image.
An Image stream and its tags provide an abstraction for referencing Docker images.
A Deployment creates a new replication controller and lets it start up pods.
Core Concepts and Terms
OpenShift for Developers6 25.09.2018

7. OpenShift for Developers7 25.09.2018
Running & Accessing OpenShift

8. Running OpenShift
OpenShift for Developers8 9/25/2018
OpenShift Online: https://manage.openshift.com/
– Free starter plan
OpenShift Origin: https://www.okd.io/
– Community-supported distribution
– Installation with Ansible Playbooks
Minishift: https://www.okd.io/minishift/
– Run OpenShift inside a VM
OpenShift in the TriCloud
– Work in Progress

9. Accessing OpenShift
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OpenShift web console
OpenShift command line tool: oc
OpenShift REST API

10. OpenShift for Developers10 25.09.2018
Building & Deploying an Image

11. Building an Image
OpenShift for Developers11 25.09.2018
OpenShift provides the ability to build images for you.
OpenShift provides four different build strategies
– Docker
– Source (S2I)
– Pipeline
– Custom

12. Building and Deploying an Image - Example
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λ oc import-image codecentric/springboot-maven3-centos --confirm
λ oc new-app springboot-maven3-centos
> ~https://github.com/sebisteiner/springboot-sample-app
λ oc expose service springboot-sample-app
Import the S2I base image.
Create a new application.
Expose the application (service) with a route.

13. OpenShift for Developers13 25.09.2018
Persistent Storage

14. Persistent Storage
OpenShift for Developers14 9/25/2018
The application can write to any part of the filesystem it has permission to.
But when the container is stopped, any changes made will be lost!
Persistent volumes can be mounted to persist data.
Persistent storage must be configured by the OpenShift cluster administrator.
– The application developer doesn’t has to care about the underlying storage
technology.

15. OpenShift for Developers15 25.09.2018
Problem Analysis

16. Debugging
OpenShift for Developers16 25.09.2018
Open a remote shell session to a pod
List all available pods in the current project
oc get po
oc rsh <podname>
Forward a local port to a pod (for remote debugging)
oc port-forward -p <podname> <local_port>:<pod_port>

17. Health Checks
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The readiness probe checks whether my application has started up, before sending
traffic to it.
– Used when a new pod is created.
– If it keeps failing the deployment will be marked as failed.
The liveness probe checks if my application is still responding after start up.
– If it keeps failing, the pod will be shutdown and replaced with a new pod.
λ oc set probe dc/springboot-sample-app
> --readiness --get-url=http://:8080

18. OpenShift for Developers18 25.09.2018
Application Lifecycle Management

19. Deployment Strategies
OpenShift for Developers19 9/25/2018
Rolling deployment
– Replaces instances of the previous version slowly with instances of the new
version.
– It enables zero-downtime deployments.
Recreate deployment
– Stops previous version before starting new instances.
Pre- and Post lifecycle hooks can be added to a deployment.

20. Advanced Deployment Strategies
OpenShift for Developers20 25.09.2018
Blue-Green Deployment
– Two running deployment configurations, each exposed to a different service.
– We create a new route pointing to the new version.
– When ready we change the productive route to point to the new service.
A/B Deployment
– Let’s you try out a new version of the application in a limited way in production.
– We create a weighted route with multiple services.
– Each service is assigned a weight and the requests are distributed accordingly.

21. Thank you – Any Questions?
Sebastian Steiner
Sebastian.Steiner@Trivadis.com
25.09.2018 OpenShift for Developers21
@sebisteiner