1.
Future of Microservices
Jakub Hadvig
OpenShift Engineering

2.
Microservice ?

3.
Microservice
● Software architecture
● Application composed from processes
○ small and independent
○ single purpose
○ replaceable
○ isolated

4.
Microservice
● Software architecture
● Application composed from
processes
○ small independent processes
○ single purpose
○ replaceable
○ isolated

5.
Linux Containers (LXC)
● Virtualization on a operating-system level
● Single Linux host = multiple isolated Linux system
● Containers run with host kernel (fast)
● Microservices = Containers

6.
Microservices redefine the “App”
● Networked components wired together
○ Not just a “web frontend” anymore
○ HTTP frontends are just one type of component
○ Make it easy to build, manage, deploy components (tools)
● Critical: relationships between components
○ If you can’t abstract the connection between components you
can’t evolve them independently

7.
Docker
github.com/docker/docker

8.
Docker
● Containerization engine for building images
● Go
● Core functions
○ docker build = Docker images
○ docker run = Docker containers
● Dockerfile
○ DSL
○ 16 instructions

9.
Dockerfile

10.
!!! Remember “CMD” Instruction !!!

11.
Docker images
● Immutable (read-only)
● Sharable
● 80k public Docker images (DockerHub)
● Building blocks
○ Image based deployment
○ Create once, use everywhere (Dev, QA, Prod)

12.
Docker containers
● State-less
● Transient
● Cattle, no pets

13.
Docker
● What do we want?
○ Full access to the existing Docker ecosystem
○ Be able to consume images from anywhere
○ Work with upstream to improve security and reliability
○ Need tools to manage the build process and security updates
● What do we expect?
○ Manage 1M+ of running containers
○ Manage containers across multiple nodes

14.
Kubernetes
github.com/GoogleCloudPlatform/kubernetes

15.
Kubernetes
● Container cluster manager
● Manage containerized applications across a
cluster of Nodes
○ Running containers at scale
○ Provide runtime and operational tools for containers
○ Provide resource management
● Google, Red Hat, CoreOS and others…
● Go

16.
Kubernetes architecture (basics)
● Master(s)
○ (REST) API server
○ Scheduler for allocation of “containers” onto hosts
○ Manages replications and watches the system for changes
● Node(s)
○ Agent that relays informations between Node and Master
○ Manages containers (using Docker)
○ Proxy for local service routing and load-balancing

17.
Kubernetes architecture
● Etcd
○ Simple config key-value store distributed across hosts
○ Highly reliable
○ Used for service discovery
○ Simple (CURL ball) & Secure (SSL)
○ Provide high-performance operations

18.
Kubernetes work units
● Pod
○ Represents group of containers closely related together
○ 1..N containers

19.
Pods

20.
Kubernetes work units
● Service
○ Abstract set of Pods as a single IP and 1..N ports
○ Provides environment variable in other Pods and simple
TCP/UDP load balancing

21.
Services

22.
Kubernetes work units (cont..)
● Replication Controllers
○ Framework for Pods that are meant to be horizontally scaled
○ Maintain number of replicas for given Pod
○ Replicas are distributed across cluster
● Label(s)
○ Common field in all Kubernetes resources
○ Represents a 'tags' you can use to couple the work units
together

23.
Kubernetes work units (cont..)
● Route
○ Exposed service, reachable from outside

24.
So what is an new "Application"?
Pods linked together by Services:
● Edge router for www.myapp.com -> Rails frontend Pods
● Rails frontend Pods -> "backend" API Service
● "backend" API Service -> Python Pods
● Python Pods -> "postgresql" database Service
● "postgresql" Service -> PostgreSQL Pod with network
attached storage

25.
OpenShift v3
github.com/openshift/origin

26.
OpenShift v3
● Use Docker to containerize applications
● Use Kubernetes to manage them
○ Allow for Service-oriented-Architecture (Mircoservices !!!)
● Go

27.
Composition
● Kubernetes is embeddable
● Kubernetes offers us infrastructure
● OpenShift embeds it and add PaaS pieces:
○ Builds
○ ImageStreams
○ Deployments
○ Templates
○ ... others...

28.
Build
● Allows to build “stuff”
○ S2I, Docker, or Custom build
● Kubernetes schedule and execute the build inside Docker
container
● Triggers
○ webhooks
○ image change
○ config change
● Built image are pushed into a single ImageStream.

29.
ImageStream
● Build upon Docker Registry
● Abstraction for lack of functionality
○ base image
○ notify changes
○ track history

30.
Deployment
● Define the lifecycle for a single image
○ What happen when an update is pushed to Docker image?
○ What happen when application configuration is updated?
○ What happen when updated application configuration fail to
deploy?

31.
Templates
● For consumption by end users of standard
patterns
● Describes the whole application topology

32.
S2I (Source to Image)
● Don’t make developers write Dockerfile
● Providing builder images is operational responsibility
● Developers wants simple flows (From GIT repo to Docker image)
○ Push changes to Git
○ Get all dependencies installed (bundler, npm, pip, maven, etc..)
○ Commit Docker image
○ Deploy

33.
S2I (Source to Image)
● Build process fundamental elements
○ source
○ builder image
○ s2i scripts
■ assamble
■ run
● Current s2i builder images:
○ ruby, php, python, nodejs, perl, jboss
● Incremental builds (kinda)

34.
Source code
● Consuming external source repos (no hosting)
○ github && generic webhooks
● Support different SCM (bzr, mercurial, SVN, CVS, ...)

35.
OpenShift and Images
● Need tools for Docker image management
○ Think about millions of Docker containers
○ Need good quota story - OpenShift v3 Online
○ Pruning - remove old stuff
○ Content tracking and auditing
● Security

36.
Documentation, links, repos
● OpenShift 3 Technical Architecture
○ Much deeper dive into the architecture
● OpenShift 3 System Design (PEP)
● Kubernetes Repo
○ https://github.com/GoogleCloudPlatform/kubernetes
● OpenShift Repo
○ https://github.com/openshift/origin
● Sample App+Guide
○ https://github.com/openshift/origin/tree/master/examples/sample-app
● OpenShift Blog Series
○ https://blog.openshift.com/author/benparees/
● Source-To-Image project
○ https://github.com/openshift/source-to-image

37.
Thanks! Questions?