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.

Transcript

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