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
3. Container orchestration platform
4. Deploy, run and scale your services in isolated containers
5. Very Powerful
6. Large community
7. Lot’s of large company backers
8. No vendor lock in
9. Runs on
10. AWS
11. Azure
12. Google Cloud Platform
13. Bare metal
14. Your laptop
15. Minikube
16. Included in Docker Desktop Clients
17. SysEleven
18. Learning curve
19. This talk is supposed to get you started
20. I’m going to explain the basics
21. I’ll start with deploying a simple PHP Web App
22. and cover some internals
23. But first
24. Why containers?
25. Services run in isolation
26. Everything needed to run a service in one image
27. Decouple Ops and Dev
28. Make things …
29. Easier to deploy
30. Easier to upgrade system dependencies
31. Easier to scale
32. Easier to develop
33. Better performance than Virtual Machines
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”]
36. docker build -t symfony-demo:2.0.0 .
37. docker run -p 8080:80 symfony-demo:2.0.0
38. Kubernetes helps you running containers
39. OK, sold
40. Let’s define some core concepts first
41. Kubernetes Cluster
42. • A docker image built from a Dockerfile that contains everything a service needs to run Image
43. • A container runs a docker image. • Only 1 process can run inside of a container Container
44. • A group of 1 or more containers • Same port space • Ports are not accessible from outside of the pod Pod
45. • Defines and manages how many instances of a pod should run Replica Set
46. • Manages updates and rollbacks of replica sets Deployment
47. • Makes a port of a pod accessible to other pods Service
48. • Makes a service accessible to the outside of Kubernetes Ingress
49. • A physical server • Containers get distributed automatically Node
50. • Configuration that can be mounted inside of a container ConfigMap
51. • Volumes can be mounted into a container to access a ConfigMap, Secret or a folder on the host Volumes
52. • Dedicated environment to deploy services in Namespaces
53. Example
54. PHP-FPM NGINX LINKERD STATSD MEM CACHED MONGO ROUTER PHP Application POD
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
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
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
58. To interact with Kubernetes
59. Tooling
60. kubectl
61. $ kubectl get pods
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
63. REST API
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",
65. kubernetes-dashboard
67. Helm The package manager for Kubernetes
68. $ helm install stable/wordpress
69. Practical example
70. Preparations
71. Install Docker Client
73. Install helm
74. $ brew install kubernetes-helm
75. $ helm init
76. Install kubernetes-dashboard
77. $ helm install stable/kubernetes-dashboard -f kubernetes- dashboard.yaml
78. Install nginx-ingress-controller
79. $ helm install stable/nginx-ingress -f ingress- controller.yaml
80. Let’s deploy the symfony demo app
81. https:/ /github.com/symfony/demo
82. First the Dockerfile
83. PHP
84. Copy our code
85. Build the project
86. Composer install
87. yarn install
88. yarn run build
89. Build the image
90. docker build -t symfony-demo:2.0.0 .
91. Demo
92. Now we have to tell Kubernetes what to do with the image
93. Resources are defined in YAML or JSON
94. Deployment
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:
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: /
97. Many more options configurable
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 • …
99. Service
100. kind: Service apiVersion: v1 metadata: name: symfony-demo spec: ports: - name: http port: 80 targetPort: 80 protocol: TCP selector: app: symfony-demo
101. Ingress
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
103. Creating everything
104. kubectl apply -f deployment/webapp.yaml
106. Rolling Deployments
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
108. kubectl apply -f deployment/webapp.yaml
109. Demo
110. These are the basics
111. There are other types of deploying things into Kubernetes
112. CronJobs
113. Regularly repeating jobs
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
115. How does Kubernetes work internally
116. Service Discovery
117. Within a pod
118. Shared port namespace
119. Separate file systems
120. Separate process spaces
121. Network wise everything behaves like localhost
122. Between pods
123. You have to expose ports with services
124. kind: Service apiVersion: v1 metadata: name: symfony-demo spec: ports: - name: http port: 80 targetPort: 80 protocol: TCP selector: app: symfony-demo
125. Every service has a virtual IP address
126. $ kubectl get service symfony-demo NAME TYPE CLUSTER-IP PORT(S) AGE symfony-demo ClusterIP 10.106.119.24 80/TCP 6d
127. Discoverable in other containers by
128. Environment Variables
129. SYMFONY_DEMO_SERVICE_HOST=10.106.119.24 SYMFONY_DEMO_SERVICE_PORT=80
130. DNS
131. $ nslookup symfony-demo Server: 10.0.0.10 Address 1: 10.0.0.10 Name: symfony-demo Address 1: 10.106.119.24
132. $ curl http://symfony-demo
133. Alternatively
134. Service Mesh
135. LinkerD https:/ /linkerd.io/
136. Istio https:/ /istio.io/
137. Conduit https:/ /conduit.io/
138. PHP-FPM NGINX LINKERD STATSD MEM CACHED MONGO ROUTER PHP Application POD
139. PHP-FPM NGINX LINKERD STATSD MEM CACHED MONGO ROUTER PHP Application POD NodeJS LINKERD NodeJS Service POD NodeJS LINKERD NodeJS Service POD
140. PHP-FPM NGINX LINKERD STATSD MEM CACHED MONGO ROUTER PHP Application POD NodeJS LINKERD NodeJS Service POD NodeJS LINKERD NodeJS Service POD
141. PHP-FPM NGINX LINKERD STATSD MEM CACHED MONGO ROUTER PHP Application POD NodeJS LINKERD NodeJS Service POD NodeJS LINKERD NodeJS Service POD
142. PHP-FPM NGINX LINKERD STATSD MEM CACHED MONGO ROUTER PHP Application POD NodeJS LINKERD NodeJS Service POD NodeJS LINKERD NodeJS Service POD
143. Benefits
144. Advanced routing
145. Prefer service in current namespace, fall back to default namespace
146. Canary deployments
147. A/B Testing
148. Advanced monitoring
150. Profiling
151. Zipkin
153. What about data?
154. Storage
155. Volumes
156. https:/ /kubernetes.io/docs/concepts/ storage/volumes/
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: {}
158. Persistent Storage
159. You define a Persistent Volume or Storage Class, e.g. NFS, …
160. Depends on your Kubernetes Setup
161. Each pod can specify a Persistent Volume Claim
162. apiVersion: v1 kind: PersistentVolumeClaim metadata: name: postgresql-pv-claim labels: name: postgresql spec: storageClassName: generic accessModes: - ReadWriteOnce resources: requests: storage: 10Gi
163. And then mount the Claim into a Volume in a container
164. apiVersion: extensions/v1beta1 kind: Deployment metadata: name: postgresql spec: template: spec: containers: … volumes: - name: postgresql-data persistentVolumeClaim: claimName: postgresql-pv-claim
165. https:/ /kubernetes.io/docs/concepts/ storage/persistent-volumes/
166. Configuration
167. Should not be included in the docker image
168. ConfigMap
169. Key/Value Store
170. kind: ConfigMap apiVersion: v1 metadata: name: special-config data: special-key: value bool-value: true
171. Can be accessed in a pod through environment variables
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
173. spec: containers: - name: test-container image: k8s.gcr.io/busybox command: [ "/bin/sh", "-c", "env" ] envFrom: - configMapRef: name: special-config
174. Can be accessed through volumes
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
176. https:/ /kubernetes.io/docs/tasks/ configure-pod-container/configure-pod- configmap/
177. Secret
178. Storage for sensitive information
179. https:/ /kubernetes.io/docs/concepts/ configuration/secret
180. Scaling
181. Manual Scaling
182. kubectl scale --replicas=3 deployment/my-app
183. AutoScaling
184. https:/ /kubernetes.io/docs/user-guide/ horizontal-pod-autoscaling/
185. Summary
186. Powerful
187. Helpful
188. Fast paced development
189. https:/ /gravitational.com/blog/ kubernetes-release-cycle/
190. Keep up to date
191. Documentation
192. https:/ /kubernetes.io/docs/
193. KubeCons
194. https:/ /www.youtube.com/channel/ UCvqbFHwN-nwalWPjPUKpvTA
195. http:/ /speakerdeck.com/ u/bastianhofmann
196. mail@bastianhofmann.de https:/ /twitter.com/BastianHofmann
197. Backup Slides
198. Figuring out what’s going on inside Kubernetes
199. Monitoring
200. Heapster
201. https:/ /github.com/kubernetes/heapster
202. Takes metrics from Kubernetes and stores them in a monitoring solution
203. InfluxDB
204. Prometheus
205. Grafana for displaying the data
208. https:/ /blog.kublr.com/how-to-utilize-the- heapster-influxdb-grafana-stack-in- kubernetes-for-monitoring- pods-4a553f4d36c9
209. Logging
210. kubectl logs
211. $ kubectl logs symfony-demo-5b75f5fc6- c7wr9
212. Log to stdout & stderr
213. Automatically written to disk
214. DaemonSet Log collector
215. • Logstash • Fluentd • Filebeat
216. Central log management
218. https:/ /www.elastic.co/blog/shipping- kubernetes-logs-to-elasticsearch-with- filebeat