Containers are set to be the next big evolutionary step in virtualization. An increasing number of companies are embracing containers to deliver complex mission-critical applications. Kubernetes is a powerful open-source system for managing containerized applications in a clustered environment.

1. www.aspex.be
Kubernetes
Container Orchestration for Prod-Grade People

2. www.aspex.be 2@Thomas_VanLaere
user$ whoami
thomasvanlaere
— Dev turned Azure consulting

3. www.aspex.be
“Treat your datacenter as one massive warehouse-scale computer”

4. www.aspex.be
Why K8S?
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— Kubernetes is a framework for building distributed platform
— No hand holding

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What K8s?
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Load Balancers, Routers, DNS, etc..
Kubernetes
Infrastructure
Storage
(Block, NFS, etc..)
Machine
(VM, Phys, etc..)
Network
(L2, L3, VPN)

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Contracts and boxes
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apiVersion: v1
kind: pod
metadata:
name: nginx
labels:
app: nginx
spec:
containers:
image: nginx:1.10.0
Pick a box
Apply formalities

8. www.aspex.be
How Dockerfile?
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FROM alpine:3.7
LABEL maintainer="NGINX Docker Maintainers <docker-maint@nginx.com>"
ENV NGINX_VERSION 1.10.0
RUN addgroup -S nginx
&& adduser -D -S -h /var/cache/nginx -s /sbin/nologin -G nginx nginx
&& apk add --no-cache --virtual .build-deps
gcc
&& ln -sf /dev/stdout /var/log/nginx/access.log
&& ln -sf /dev/stderr /var/log/nginx/error.log
COPY nginx.conf /etc/nginx/nginx.conf
COPY nginx.vh.default.conf /etc/nginx/conf.d/default.conf
EXPOSE 80
CMD ["nginx", "-g", "daemon off;"]
Pick a box
Apply formalities

9. www.aspex.be
Ah, contracts.
9
apiVersion: v1
kind: pod
metadata:
name: nginx
labels:
app: nginx
spec:
containers:
image: nginx:1.10.0

10. www.aspex.be
Deploy, go.
apiVersion: v1
kind: pod
metadata:
name: nginx
labels:
app: nginx
spec:
containers:
image: nginx:1.10.0
kube-apiserver
Node X
Kubelet
Container
Runtime
Kube-proxy

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Deploy, go.
11
apiVersion: v1
kind: pod
metadata:
name: nginx
labels:
app: nginx
spec:
containers:
image: nginx:1.10.0
kube-apiserver
Node X
Kubelet
Container
Runtime
Kube-proxy
Kube-scheduler

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Automated Deployments
12

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Kubernetes: bin packing
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Kubernetes: existing infrastructure
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What Resources?
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— Pod
— Group of tightly coupled containers and volumes
— Volumes
— Pod level storage and configs
— Replica Set
— A loop that drives current state towards a desired state
— Deployments
— Like Replica Sets but with deployment strategy capabilities
— Service
— A set of running pods that work together

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What Container?
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— Isolated executable environment
— Just another box
Container
App
Bin/lib

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What Registry?
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Build
Registry
C
C
C
C
C
C
— Distributed via Image Registries
— K8s supports public and private
— Containers are created with images

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What Pods?
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— Smallest possible unit
— Disposable entities
— Unique IP
— One or multiple containers
— Shares network namespace
— Localhost
— One or multiple volumes
Pod
Container X
Container Y
IP
Volume
A
Volume
B

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Why ReplicaSet?
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— Drives current state towards desired state
— App: nginx
— Replicas: 1
Node0
Pod
Container
Node1 Node2

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Why ReplicaSet?
20
— Drives current state towards desired state
— App: nginx
— Replicas: 3
Node0
Pod
Container
Node1
Pod
Container
Node2
Pod
Container

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Why ReplicaSet?
21
— Drives current state towards desired state
— App: nginx
— Replicas: 3
Node0
Pod
Container
Node1
Pod
Container
Node2

22. www.aspex.be
Why ReplicaSet?
22
— Drives current state towards desired state
— App: nginx
— Replicas: 3
Node0
Pod
Container
Node1
Pod
Container
Node2
Pod
Container

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Shh, secrets.
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— Secrets
— Think app settings
— Configmaps
— Think config artifacts
K8s control plane
Secret etcdKube-apiserver

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Oh, secrets.
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— Example
— Mount my config as a file on disk
K8s control plane
etcd
Kube-
apiserver
Node0
kubelet pod
pod
Secret
/etc/nginx/conf.d

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Services.
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apiVersion: v1
kind: pod
metadata:
name: nginx
labels:
app: nginx
spec:
containers:
image: nginx:1.10.0

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Why Services?
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— A logical grouping of pods
— Stable virtual IP and port
— DNS
— Optional but highly recommended
— Updates on backend change
Pod
Container
Service
Pod
Container
Pod
Container
Labels:
app: nginx
Labels:
app: nginx
Labels:
app: nginx
Selector:
app: nginx

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Kubernetes Storage Model: PV & PVC
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Pools w/ Persistent Volumes
Az Ma
Disks
iSCSI
Administrator
Registers PVs in the pool

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Kubernetes Storage Model: PV & PVC
28
Pools w/ Persistent Volumes
Az Ma
Disks
iSCSI
Administrator
Registers PVs in the pool
Developer
Claim
Claims a PV from the pool

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Kubernetes Storage Model: PV & PVC
29
Pools w/ Persistent Volumes
Az Ma
Disks
iSCSI
Administrator
Registers PVs in the pool
Developer
pod
PV
ClaimReferences the claim in a pod Container

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Kubernetes: Dynamic provisioning w/ Storage Classes!
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Storage Classes
Administrator
Registers Storage Classes
FastSSDSlowHDD

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Kubernetes: Dynamic provisioning w/ Storage Classes!
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Storage Classes
Administrator
Registers Storage Classes
FastSSDSlowHDD
Developer
Claim
Claims a PV from the pool

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Kubernetes: Dynamic provisioning w/ Storage Classes!
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Storage Classes
Administrator
Registers Storage Classes
FastSSDSlowHDD
Developer
pod
PV
Claim
References the claim in a pod
Container

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Kubernetes: Demo
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API
Endpoint
(Python)
Redis
Worker
(.NET)
SQL Server
Frontend
(NodeJS)

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Kubernetes: Demo
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Node0
Pod
MS SQL Server
Node1
Pod
.NET Worker
Pod
Python Flask
Pod
NodeJS
Pod
DB setup Job
Pod
Redis Cache
NodeJS
Service
MS SQL Server
Service
Python Flask
Service
Button
Browser
SSMS
Redis
Service
Public IP
Public IP
Public IP

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Don’t get hacked
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— Ingress
— Contains the mapping between URL paths and Services.
— Ingress Controller
— Pod which runs the ingress controller and nginx
— Ingress Service
— The Ingress Controller needs a public IP Address.

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Kubernetes: Demo without Ingress
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Node0
Pod
MS SQL Server
Node1
Pod
.NET Worker
Pod
Python Flask
Pod
NodeJS
Pod
DB setup Job
Pod
Redis Cache
NodeJS
Service
MS SQL Server
Service
Python Flask
Service
Button
Browser
SSMS
Redis
Service
Public IP
Public IP
Public IP

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Node1
Kubernetes: With Ingress
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Node0
Pod
MS SQL Server
Pod
.NET Worker
Pod
Python Flask
Pod
NodeJS
Pod
DB setup Job
Pod
Redis Cache
NodeJS
Service
MS SQL
Server
Service
Python Flask
ServiceButton
Browser
SSMS
Ingress
- Path: /
- Service: frontend
- Path: /api
- Service: endpoint
Ingress
Controller
NGINX Ingress
Controller
NGINX
Redis
Service
Public IP
Ingress
Service
80/443

38. www.aspex.be
THANK YOU
QUESTIONS?