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Introduction to Kubernetes

Introduction to Kubernetes

Getting started with Kubernetes Kubernetes is a very powerful container orchestration platform that is quickly gaining traction and gives you lots of benefits in deploying, running and scaling your microservice web application. But it has also a steep learning curve. In this talk I will introduce you to Kubernetes, why you would want to use it and all the tooling around Kubernetes with the help of practical examples.

Bastian Hofmann

April 20, 2018
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  1. Introduction to
    Kubernetes
    @BastianHofmann

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  2. View Slide

  3. View Slide

  4. View Slide

  5. Container
    orchestration
    platform

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  6. Deploy, run and
    scale your services
    in isolated
    containers

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  7. Very Powerful

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  8. Large community

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  9. Lot’s of large
    company backers

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  10. No vendor lock in

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  11. Runs on

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  12. AWS

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  13. Azure

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  14. Google Cloud
    Platform

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  15. Bare metal

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  16. Your laptop

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  17. Minikube

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  18. Included in Docker
    Desktop Clients

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  19. Learning curve

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  20. This talk is supposed
    to get you started

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  21. I’m going to explain
    the basics

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  22. I’ll start with
    deploying a simple
    PHP Web App

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  23. and cover things
    like Logging,
    Monitoring,…

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  24. But first

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  25. Why containers?

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  26. Services run in
    isolation

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  27. Everything needed
    to run a service in
    one image

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  28. Decouple
    Ops and Dev

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  29. Make things …

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  30. Easier to deploy

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  31. Easier to upgrade
    system
    dependencies

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  32. Easier to scale

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  33. Easier to develop

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  34. More performant
    than
    Virtual Machines

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  35. View Slide

  36. FROM php:7.2-apache
    WORKDIR /var/www/html
    RUN apt-get update -y && \
    apt-get install -y --no-install-recommends \
    curl \
    rm -rf /var/lib/apt/lists/*
    COPY composer.* /var/www/html/
    ENV COMPOSER_HOME /tmp
    RUN composer install
    COPY . /var/www/html/
    EXPOSE 80
    ENTRYPOINT [“apache2”, “-DFOREGROUND”]

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  37. docker build -t symfony-demo:2.0.0 .

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  38. docker run -p 8080:80 symfony-demo:2.0.0

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  39. Kubernetes helps
    you running
    containers

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  40. OK, sold

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  41. Let’s define some
    core concepts first

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  42. Kubernetes
    Cluster

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  43. Image
    • A docker image
    built from a
    Dockerfile that
    contains everything
    a service needs to
    run

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  44. • A container runs a
    docker image.
    • Only 1 process
    can run inside of a
    container
    Container

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  45. Pod
    • A group of 1 or more
    containers
    • Same port space
    • Ports are not
    accessible from
    outside of the pod

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  46. Replica Set
    • Defines and
    manages how
    many instances
    of a pod should
    run

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  47. Deployment
    • Manages
    updates and
    rollbacks of
    replica sets

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  48. Service
    • Makes a port
    of a pod
    accessible to
    other pods

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  49. Ingress
    • Makes a
    service
    accessible to
    the outside
    of
    Kubernetes

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  50. Node
    • A physical server
    • Containers get
    distributed
    automatically

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  51. ConfigMaps
    & Secrets
    • Configuration that
    can be mounted
    inside of a
    container

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  52. Volumes
    • Volumes can be
    mounted into a
    container to access
    a ConfigMap, Secret
    or a folder on the
    host

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  53. Namespaces
    • Dedicated
    environment
    to deploy
    services in

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  54. Docker registries

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  55. Example

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  56. PHP-FPM
    NGINX
    LINKERD
    STATSD
    MEM

    CACHED
    MONGO

    ROUTER
    PHP Application POD

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  57. PHP-FPM
    NGINX
    LINKERD
    STATSD
    MEM

    CACHED
    MONGO

    ROUTER
    PHP Application POD
    ReplicaSet: 2 instances
    PHP-FPM
    NGINX
    LINKERD
    STATSD
    MEM

    CACHED
    MONGO

    ROUTER
    PHP Application POD

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  58. PHP-FPM
    NGINX
    LINKERD
    STATSD
    MEM

    CACHED
    MONGO

    ROUTER
    ReplicaSet: 2 instances
    PHP-FPM
    NGINX
    LINKERD
    STATSD
    MEM

    CACHED
    MONGO

    ROUTER
    CONFIG
    WEB :80
    PHP Application POD PHP Application POD

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  59. PHP-FPM
    NGINX
    LINKERD
    STATSD
    MEM

    CACHED
    MONGO

    ROUTER
    ReplicaSet: 2 instances
    PHP-FPM
    NGINX
    LINKERD
    STATSD
    MEM

    CACHED
    MONGO

    ROUTER
    CONFIG
    WEB :80
    https://php-app.k8s.foo.com:443/
    PHP Application POD PHP Application POD

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  60. To interact with
    Kubernetes

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  61. Tooling

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  62. kubectl

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  63. $ kubectl get pods

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  64. NAME READY STATUS RESTARTS AGE
    kubernetes-dashboard-5b5bf59977-t9xb9 1/1 Running 2 9d
    nginx-ingress-controller-5549f5597c-97kcw 0/1 Running 2 9d
    nginx-ingress-default-backend-564d9d9477-tmnnr 1/1 Running 4 9d
    mysql-556c9b5bcb-5jdrt 1/1 Running 1 8d
    symfony-demo-5b75f5fc6-c7wr9 1/1 Running 0 8d
    symfony-demo-5b75f5fc6-jg8n4 1/1 Running 23 8d

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  65. REST API

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  66. $ kubectl proxy --port=8080
    $ curl http://localhost:8080/api/v1/namespaces/default/pods
    {
    "kind": "PodList",
    "apiVersion": "v1",
    "metadata": {
    "selfLink": "/api/v1/namespaces/default/pods",
    "resourceVersion": "336834"
    },
    "items": [
    {
    "metadata": {
    "name": "kubernetes-dashboard-5b5bf59977-t9xb9",
    "generateName": "kubernetes-dashboard-5b5bf59977-",

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  67. kubernetes-
    dashboard
    https://github.com/kubernetes/dashboard

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  68. View Slide

  69. Helm
    The package manager for Kubernetes
    https://helm.sh/

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  70. $ helm install stable/wordpress

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  71. Practical example

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  72. Preparations

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  73. Install Docker Client

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  74. $ brew cask install docker

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  75. View Slide

  76. Install helm

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  77. $ brew install kubernetes-helm

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  78. $ helm init

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  79. Install
    kubernetes-dashboard

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  80. ingress:
    enabled: true
    hosts:
    - kubernetes-dashboard.local.k8s

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  81. $ helm install stable/kubernetes-dashboard
    -f kubernetes-dashboard.yaml

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  82. Install
    nginx-ingress-controller

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  83. rbac:
    create: true
    controller:
    hostNetwork: true

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  84. $ helm install stable/nginx-ingress -f
    ingress-controller.yaml

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  85. Let’s deploy the
    symphony demo
    app

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  86. https://github.com/symfony/demo

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  87. First the Dockerfile

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  88. PHP

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  89. Copy our code

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  90. Build the project

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  91. Composer install

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  92. yarn install

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  93. Build the image

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  94. docker build -t symfony-demo:2.0.0 .

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  95. Demo

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  96. Since it’s all local we
    don’t need to push it to
    a registry

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  97. Now we have to tell
    Kubernetes what to do
    with the image

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  98. Resources are defined
    in YAML or JSON

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  99. Deployment

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  100. kind: Deployment
    apiVersion: extensions/v1beta1
    metadata:
    name: symfony-demo
    spec:
    revisionHistoryLimit: 3
    template:
    metadata:
    labels:
    app: symfony-demo
    spec:
    containers:
    - name: symfony-demo
    image: symfony-demo:1.0.0
    imagePullPolicy: Never
    ports:
    - containerPort: 80

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  101. containers:
    - name: symfony-demo
    image: symfony-demo:1.0.0
    imagePullPolicy: Never
    ports:
    - containerPort: 80
    livenessProbe:
    httpGet:
    path: /
    port: 80
    timeoutSeconds: 1
    initialDelaySeconds: 10
    readinessProbe:
    httpGet:
    path: /
    port: 80
    timeoutSeconds: 1

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  102. Many more options
    configurable

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  103. •Setting environment variables
    •Mounting volumes
    •Requesting resources
    •Defining upgrade strategies
    •Defining command
    •Configure networking
    •Configure affinities
    •LifeCycle events
    •…

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  104. Service

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  105. kind: Service
    apiVersion: v1
    metadata:
    name: symfony-demo
    spec:
    ports:
    -
    name: http
    port: 80
    targetPort: 80
    protocol: TCP
    selector:
    app: symfony-demo

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  106. Ingress

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  107. kind: Ingress
    apiVersion: extensions/v1beta1
    metadata:
    name: symfony-demo
    spec:
    rules:
    - host: symfony-demo.local.k8s
    http:
    paths:
    - path: /
    backend:
    serviceName: symfony-demo
    servicePort: 80

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  108. Creating everything

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  109. kubectl apply -f deployment/webapp.yaml

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  110. View Slide

  111. Rolling
    Deployments

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  112. kind: Deployment
    apiVersion: extensions/v1beta1
    metadata:
    name: symfony-demo
    spec:
    revisionHistoryLimit: 3
    template:
    metadata:
    labels:
    app: symfony-demo
    spec:
    containers:
    - name: symfony-demo
    image: symfony-demo:1.1.0
    imagePullPolicy: Never
    ports:
    - containerPort: 80

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  113. kubectl apply -f deployment/webapp.yaml

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  114. Demo

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  115. These are the
    basics

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  116. Let’s talk about
    some other
    interesting and
    important aspects

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  117. There are other
    types of deploying
    things into
    Kubernetes

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  118. DaemonSets

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  119. Ensure that a pod
    runs once on every
    node

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  120. Log collection
    daemon

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  121. Monitoring agent

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  122. Service mesh
    containers

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  123. View Slide

  124. Basically works like
    deployments

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  125. But roll out strategy
    is different

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  126. CronJobs

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  127. Regularly repeating
    jobs

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  128. apiVersion: batch/v1beta1
    kind: CronJob
    metadata:
    name: cron-job
    spec:
    schedule: "*/1 * * * *"
    jobTemplate:
    spec:
    template:
    spec:
    containers:
    - name: cron-job
    image: your-cron-job
    restartPolicy: OnFailure

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  129. How does
    Kubernetes work
    internally

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  130. Service Discovery

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  131. Within a pod

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  132. Shared port
    namespace

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  133. Separate file
    systems

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  134. Separate process
    spaces

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  135. Network wise
    everything behaves
    like localhost

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  136. Between pods

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  137. You have to expose
    ports with services

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  138. kind: Service
    apiVersion: v1
    metadata:
    name: symfony-demo
    spec:
    ports:
    -
    name: http
    port: 80
    targetPort: 80
    protocol: TCP
    selector:
    app: symfony-demo

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  139. Every service has a
    virtual IP address

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  140. $ kubectl get service symfony-demo
    NAME TYPE CLUSTER-IP PORT(S) AGE
    symfony-demo ClusterIP 10.106.119.24 80/TCP 6d

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  141. Discoverable in
    other containers by

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  142. Environment
    Variables

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  143. SYMFONY_DEMO_SERVICE_HOST=10.106.119.24
    SYMFONY_DEMO_SERVICE_PORT=80

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  144. DNS

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  145. $ nslookup symfony-demo
    Server: 10.0.0.10
    Address 1: 10.0.0.10
    Name: symfony-demo
    Address 1: 10.106.119.24

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  146. $ curl http://symfony-demo

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  147. Alternatively

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  148. Service Mesh

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  149. LinkerD
    https://linkerd.io/

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  150. Istio
    https://istio.io/

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  151. Conduit
    https://conduit.io/

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  152. Runs as

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  153. DaemonSet

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  154. Sidecar container

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  155. PHP-FPM
    NGINX
    LINKERD
    STATSD
    MEM

    CACHED
    MONGO

    ROUTER
    PHP Application POD

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  156. PHP-FPM
    NGINX
    LINKERD
    STATSD
    MEM

    CACHED
    MONGO

    ROUTER
    PHP Application POD
    NODEJS LINKERD
    STATSD
    Other service POD
    NODEJS LINKERD
    STATSD
    Other service POD

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  157. PHP-FPM
    NGINX
    LINKERD
    STATSD
    MEM

    CACHED
    MONGO

    ROUTER
    PHP Application POD
    NODEJS LINKERD
    STATSD
    Other service POD
    NODEJS LINKERD
    STATSD
    Other service POD

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  158. PHP-FPM
    NGINX
    LINKERD
    STATSD
    MEM

    CACHED
    MONGO

    ROUTER
    PHP Application POD
    NODEJS LINKERD
    STATSD
    Other service POD
    NODEJS LINKERD
    STATSD
    Other service POD

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  159. Benefits

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  160. Advanced routing

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  161. Prefer service in
    current
    namespace, fall
    back to default
    namespace

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  162. Canary
    deployments

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  163. A/B Testing

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  164. Advanced
    monitoring

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  165. View Slide

  166. Profiling

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  167. Zipkin
    https://zipkin.io/

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  168. View Slide

  169. Accessing
    Kubernetes from
    the outside

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  170. Port forwarding
    through kubectl

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  171. $ kubectl port-forward $POD_NAME 8080:80

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  172. The ingress
    controller

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  173. Nginx

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  174. haproxy

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  175. Istio

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  176. View Slide

  177. A controller listens
    to all ingresses and
    routes traffic from
    the outside to the
    correct service

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  178. kind: Ingress
    apiVersion: extensions/v1beta1
    metadata:
    name: symfony-demo
    spec:
    rules:
    - host: symfony-demo.local.k8s
    http:
    paths:
    - path: /
    backend:
    serviceName: symfony-demo
    servicePort: 80

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  179. What about data?

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  180. Storage

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  181. Volumes

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  182. https://kubernetes.io/docs/concepts/storage/volumes/

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  183. apiVersion: v1
    kind: Pod
    metadata:
    name: test-pd
    spec:
    containers:
    - image: k8s.gcr.io/test-webserver
    name: test-container
    volumeMounts:
    - mountPath: /cache
    name: cache-volume
    volumes:
    - name: cache-volume
    emptyDir: {}

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  184. Persistent Storage

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  185. You define a
    Persistent Volume,
    e.g. NFS

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  186. Each pod can
    specify a Persistent
    Volume Claim

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  187. And then mount
    the Claim into a
    Volume in a
    container

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  188. https://kubernetes.io/docs/concepts/storage/persistent-
    volumes/

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  189. Configuration

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  190. Should not be
    included in the
    docker image

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  191. ConfigMap

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  192. Key/Value Store

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  193. kind: ConfigMap
    apiVersion: v1
    metadata:
    name: special-config
    data:
    special-key: value
    bool-value: true

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  194. Can be accessed
    in a pod through
    environment
    variables

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  195. spec:
    containers:
    - name: test-container
    image: k8s.gcr.io/busybox
    command: [ "/bin/sh", "-c", "env" ]
    env:
    - name: SPECIAL_KEY
    valueFrom:
    configMapKeyRef:
    name: special-config
    key: special-key

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  196. spec:
    containers:
    - name: test-container
    image: k8s.gcr.io/busybox
    command: [ "/bin/sh", "-c", "env" ]
    envFrom:
    - configMapRef:
    name: special-config

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  197. Can be accessed
    through volumes

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  198. spec:
    containers:
    - name: test-container
    image: k8s.gcr.io/busybox
    command: [ "/bin/sh", "-c", "ls /etc/config/" ]
    volumeMounts:
    - name: config-volume
    mountPath: /etc/config
    volumes:
    - name: config-volume
    configMap:
    name: special-config

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  199. https://kubernetes.io/docs/tasks/configure-pod-container/
    configure-pod-configmap/

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  200. Secret

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  201. Storage for sensitive
    information

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  202. https://kubernetes.io/docs/concepts/configuration/secret

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  203. Figuring out what’s
    going on inside
    Kubernetes

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  204. Monitoring

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  205. Heapster

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  206. https://github.com/kubernetes/heapster

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  207. Takes metrics from
    Kubernetes and
    stores them in a
    monitoring solution

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  208. InfluxDB

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  209. Prometheus

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  210. Grafana for
    displaying the data

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  211. View Slide

  212. View Slide

  213. https://blog.kublr.com/how-to-utilize-the-heapster-influxdb-
    grafana-stack-in-kubernetes-for-monitoring-
    pods-4a553f4d36c9

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  214. Logging

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  215. kubectl logs

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  216. $ kubectl logs symfony-demo-5b75f5fc6-c7wr9

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  217. Log to
    stdout & stderr

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  218. Automatically
    written to disk

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  219. DaemonSet Log
    collector

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  220. • Logstash
    • Fluentd
    • Filebeat

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  221. Central log
    management

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  222. View Slide

  223. https://www.elastic.co/blog/shipping-kubernetes-logs-to-
    elasticsearch-with-filebeat

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  224. Scaling

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  225. Manual Scaling

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  226. kubectl scale
    --replicas=3
    deployment/my-app

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  227. AutoScaling

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  228. View Slide

  229. https://kubernetes.io/docs/user-guide/horizontal-pod-
    autoscaling/

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  230. Summary

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  231. Powerful

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  232. Helpful

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  233. Fast paced
    development

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  234. https://gravitational.com/blog/kubernetes-release-cycle/

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  235. Keep up to date

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  236. Documentation

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  237. https://kubernetes.io/docs/

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  238. KubeCons

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  239. https://www.youtube.com/channel/UCvqbFHwN-
    nwalWPjPUKpvTA

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  240. http://speakerdeck.com/u/bastianhofmann

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  241. http://twitter.com/BastianHofmann
    http://lanyrd.com/people/BastianHofmann
    http://speakerdeck.com/u/bastianhofmann
    [email protected]

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