Introduction to 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.

Transcript

1. @BastianHofmann
   Introduction to Kubernetes
   Bastian Hofmann
   

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3. Container orchestration platform
   

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

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5. Very Powerful
   

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6. Large community
   

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7. Lot’s of large company backers
   

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8. No vendor lock in
   

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9. Runs on
   

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10. AWS
    

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11. Azure
    

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12. Google Cloud Platform
    

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13. Bare metal
    

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14. Your laptop
    

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15. Minikube
    

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16. Included in Docker Desktop Clients
    

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17. SysEleven
    

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18. Learning curve
    

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19. This talk is supposed to get you
    started
    

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20. I’m going to explain the basics
    

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

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22. and cover some internals
    

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23. But first
    

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24. Why containers?
    

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25. Services run in isolation
    

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26. Everything needed to run a service in
    one image
    

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27. Decouple
    Ops and Dev
    

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28. Make things …
    

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29. Easier to deploy
    

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30. Easier to upgrade system
    dependencies
    

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31. Easier to scale
    

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32. Easier to develop
    

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33. Better performance than
    Virtual Machines
    

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35. 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/*
    ENV TMP_DIR /tmp
    COPY . /var/www/html/
    EXPOSE 80
    ENTRYPOINT [“apache2”, “-DFOREGROUND”]
    

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

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

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38. Kubernetes helps you running
    containers
    

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39. OK, sold
    

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40. Let’s define some core concepts first
    

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41. Kubernetes Cluster
    

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

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

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

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

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46. • Manages updates and
    rollbacks of replica sets
    Deployment
    

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

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

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

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50. • Configuration that can be
    mounted inside of a
    container
    ConfigMap
    

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

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52. • Dedicated environment to
    deploy services in
    Namespaces
    

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53. Example
    

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54. PHP-FPM
    NGINX
    LINKERD
    STATSD
    MEM
    
    CACHED
    MONGO
    
    ROUTER
    PHP Application POD
    

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55. 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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56. 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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57. 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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58. To interact with Kubernetes
    

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59. Tooling
    

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60. kubectl
    

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61. $ kubectl get pods
    

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62. 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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63. REST API
    

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64. $ 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",
    

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65. kubernetes-dashboard
    

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67. Helm
    The package manager for
    Kubernetes
    

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68. $ helm install stable/wordpress
    

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69. Practical example
    

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70. Preparations
    

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71. Install Docker Client
    

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73. Install helm
    

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74. $ brew install kubernetes-helm
    

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75. $ helm init
    

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76. Install
    kubernetes-dashboard
    

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

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78. Install
    nginx-ingress-controller
    

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

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80. Let’s deploy the symfony demo app
    

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

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82. First the Dockerfile
    

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83. PHP
    

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84. Copy our code
    

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85. Build the project
    

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86. Composer install
    

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87. yarn install
    

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88. yarn run build
    

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89. Build the image
    

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

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91. Demo
    

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

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93. Resources are defined in YAML or
    JSON
    

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94. Deployment
    

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95. kind: Deployment
    apiVersion: extensions/v1beta1
    metadata:
    name: symfony-demo
    spec:
    template:
    metadata:
    labels:
    app: symfony-demo
    spec:
    containers:
    - name: symfony-demo
    image: symfony-demo:1.0.0
    ports:
    

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96. containers:
    - name: symfony-demo
    image: symfony-demo:1.0.0
    ports:
    - containerPort: 80
    livenessProbe:
    httpGet:
    path: /
    port: 80
    timeoutSeconds: 1
    initialDelaySeconds: 10
    readinessProbe:
    httpGet:
    path: /
    

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97. Many more options configurable
    

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98. Many more options
    • Setting environment variables
    • Mounting volumes
    • Requesting resources
    • Defining upgrade strategies
    • Defining command
    • Configure networking
    • Configure the scheduler
    • Listen on lifecycle events
    • Configure system capabilities for the container
    • …
    

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99. Service
    

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100. 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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101. Ingress
     

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102. 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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103. Creating everything
     

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104. kubectl apply -f deployment/webapp.yaml
     

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106. Rolling Deployments
     

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107. kind: Deployment
     apiVersion: extensions/v1beta1
     metadata:
     name: symfony-demo
     spec:
     template:
     spec:
     containers:
     - name: symfony-demo
     image: symfony-demo:1.1.0
     ports:
     - containerPort: 80
     

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108. kubectl apply -f deployment/webapp.yaml
     

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109. Demo
     

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110. These are the basics
     

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111. There are other types of deploying
     things into Kubernetes
     

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112. CronJobs
     

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113. Regularly repeating jobs
     

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114. 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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115. How does Kubernetes work
     internally
     

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116. Service Discovery
     

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117. Within a pod
     

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118. Shared port namespace
     

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119. Separate file systems
     

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120. Separate process spaces
     

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121. Network wise everything behaves
     like localhost
     

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122. Between pods
     

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123. You have to expose ports with
     services
     

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124. 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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125. Every service has a virtual IP address
     

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126. $ 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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127. Discoverable in other containers by
     

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128. Environment Variables
     

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129. SYMFONY_DEMO_SERVICE_HOST=10.106.119.24
     SYMFONY_DEMO_SERVICE_PORT=80
     

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130. DNS
     

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131. $ 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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132. $ curl http://symfony-demo
     

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133. Alternatively
     

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134. Service Mesh
     

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135. LinkerD
     https:/
     /linkerd.io/
     

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136. Istio
     https:/
     /istio.io/
     

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137. Conduit
     https:/
     /conduit.io/
     

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138. PHP-FPM
     NGINX
     LINKERD
     STATSD
     MEM
     
     CACHED
     MONGO
     
     ROUTER
     PHP Application POD
     

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139. PHP-FPM
     NGINX
     LINKERD
     STATSD
     MEM
     
     CACHED
     MONGO
     
     ROUTER
     PHP Application POD
     NodeJS LINKERD
     NodeJS Service POD
     NodeJS LINKERD
     NodeJS Service POD
     

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140. PHP-FPM
     NGINX
     LINKERD
     STATSD
     MEM
     
     CACHED
     MONGO
     
     ROUTER
     PHP Application POD
     NodeJS LINKERD
     NodeJS Service POD
     NodeJS LINKERD
     NodeJS Service POD
     

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141. PHP-FPM
     NGINX
     LINKERD
     STATSD
     MEM
     
     CACHED
     MONGO
     
     ROUTER
     PHP Application POD
     NodeJS LINKERD
     NodeJS Service POD
     NodeJS LINKERD
     NodeJS Service POD
     

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142. PHP-FPM
     NGINX
     LINKERD
     STATSD
     MEM
     
     CACHED
     MONGO
     
     ROUTER
     PHP Application POD
     NodeJS LINKERD
     NodeJS Service POD
     NodeJS LINKERD
     NodeJS Service POD
     

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143. Benefits
     

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144. Advanced routing
     

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

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146. Canary deployments
     

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147. A/B Testing
     

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148. Advanced monitoring
     

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150. Profiling
     

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151. Zipkin
     

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153. What about data?
     

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154. Storage
     

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155. Volumes
     

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

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157. 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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158. Persistent Storage
     

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159. You define a Persistent Volume or
     Storage Class, e.g. NFS, …
     

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160. Depends on your Kubernetes Setup
     

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161. Each pod can specify a Persistent
     Volume Claim
     

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162. apiVersion: v1
     kind: PersistentVolumeClaim
     metadata:
     name: postgresql-pv-claim
     labels:
     name: postgresql
     spec:
     storageClassName: generic
     accessModes:
     - ReadWriteOnce
     resources:
     requests:
     storage: 10Gi
     

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

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164. apiVersion: extensions/v1beta1
     kind: Deployment
     metadata:
     name: postgresql
     spec:
     template:
     spec:
     containers:
     …
     volumes:
     - name: postgresql-data
     persistentVolumeClaim:
     claimName: postgresql-pv-claim
     

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

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166. Configuration
     

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167. Should not be included in the docker
     image
     

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168. ConfigMap
     

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169. Key/Value Store
     

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

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171. Can be accessed in a pod through
     environment variables
     

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

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174. Can be accessed through volumes
     

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

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177. Secret
     

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178. Storage for sensitive information
     

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

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180. Scaling
     

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181. Manual Scaling
     

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

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183. AutoScaling
     

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

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185. Summary
     

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186. Powerful
     

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187. Helpful
     

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188. Fast paced development
     

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

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190. Keep up to date
     

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191. Documentation
     

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192. https:/
     /kubernetes.io/docs/
     

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193. KubeCons
     

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

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

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196. mail@bastianhofmann.de
     https:/
     /twitter.com/BastianHofmann
     

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197. Backup Slides
     

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198. Figuring out what’s going on inside
     Kubernetes
     

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199. Monitoring
     

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200. Heapster
     

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

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

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203. InfluxDB
     

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204. Prometheus
     

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205. Grafana for displaying the data
     

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

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209. Logging
     

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210. kubectl logs
     

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

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212. Log to
     stdout & stderr
     

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213. Automatically written to disk
     

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214. DaemonSet Log collector
     

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215. • Logstash
     • Fluentd
     • Filebeat
     

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216. Central log management
     

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

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