!doctype html> Applications and containers at scale: OpenShift + Kubernetes + Docker

Applications and containers at scale:

OpenShift + Kubernetes + Docker

Presented by:

Steven Pousty

@TheSteve0 on Twitter, IRC, Instagram, Ingress, Skype, SmugMug, and Github


  1. Cover the tech
  2. Show some demos
  3. Wrap it up


  1. You have written web applications
  2. You like things easy

Platform as a Service

Reasons to Rebuild

Act on lessons from the past three years of running a PaaS
New technologies to build on, including Docker image-based packaging and large associated ecosystem

The New Stack

Defining Container

  • Based on Linux containers (namespaces, control groups)
  • Combines file system layers into a "Union File System"
  • Includes all of the components necessary to run a process, store persistent data, or both
  • Docker currently provides the best specification for portable applications

Containers vs. VMs

Docker and VM comparison diagram

Layers and UFS

Diagram of a multi-layered docker container

Images: More like git than tar

  • Images can be pulled from and pushed to a remote registry.
  • Images can be versioned and tagged.
  • Containers can be diffed to show how they differ from their base images.

Linking Containers

Docker links diagram
  • Containers on the same host can be linked together
  • Links between containers are not accessible outside the host
  • Links are shared via ENV and /etc/hosts

Docker: Pros and Cons


  • Extreme application portability
  • Very easy to create and work with derivative images
  • Fast boot on containers


  • Host-centric solution; not aware of anything else
  • No higher-level provisioning
  • No usage tracking / reporting


Efficient resource usage
BYOB - bring your own bits
A standard way for people to make container images
Huge ecosystem


"a system for managing containerised applications across multiple hosts"
declarative model
open source project by Google

Terminology and Architecture


  • pod: colocated group of Docker containers that share an IP and storage volumes
  • service: provides a single, stable name for set of pods and acts as basic load balancer
  • replication controller: manages the lifecycle of pods and ensures specified number are running
  • label: used to organise and select groups of objects


  • cluster: compute resources on top of which containers are built
  • node: Docker host running kubelet (node agent) and proxy services
  • master: hosts cluster-level control services, including the API server, scheduler, and controller manager
  • etcd: distributed key-value store used to persist Kubernetes system state


Runtime and operational management of containers

Manage related Docker containers as a unit
Container communication across hosts
Availability and scalability through automated deployment and monitoring of pods and their replicas, across hosts


OpenShift Logo

Design Goal

Kubernetes provides a
container runtime

OpenShift provides the
Application, DevOps, and team environment


  • application: one or more pods linked together by services; distinct, interconnected components
  • config: collection of objects describing combination of pods, services, replication controllers, environment variables, and other components
  • template: parameterised version of config for generalised reuse
  • build config: object defining source code URI, authentication for change notifications (webhooks), and build type (source-to-image or docker-builder)
  • deployment: image and settings for it: replication controller, trigger policies, and deployment strategy


  • Ability to build, manage, and deliver application descriptions at scale
  • Turning source code into new deployable components
  • Support for common workflows, the application lifecycle, and teams
    • Integration of CI/CD flows into Kubernetes; trigger builds manually or from code, app, or image changes
    • Support for projects and multi-user usage and tracking; default network isolation based on team access control



Build a single artifact containing the dependency chain for reproducible deployments
Share common technology stacks and common patterns for rolling out changes
Efficiently manage thousands of applications, auto-scaling components independently and updating them en masse
Easily provision new resources at scale and subdivide them for teams
Responsive, change-aware platform supports fault-tolerant, automated, and repeatable builds and deployments


  • We covered A LOT
  • For us, it's the Linux story again - come build with us!
  • Your world as a sys admin or developer is looking bright
    • Use containers to have an agreed upon way to managage server bits
    • We can automate some annoying things - i.e. dev env creation or autoscaling
    • Template an entire application - infra and code
    • OpenShift packages all this technology into one nice package

References and Resources