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![What do you need to package your application? ● A Dockerfile, here I am copying code from my machine to the container doing builds locally. FROM centos RUN yum install -y python-pip3 COPY . /code WORKDIR /code RUN cd /code && pip install -r requirements.txt CMD [ “myapp” ] ● And few commands Note: Don’t try this in production :p](https://image.slidesharecdn.com/makingkubernetessimplefordevelopers-170514100410/75/Making-kubernetes-simple-for-developers-9-2048.jpg)
Uploaded bySuraj Deshmukh
Making kubernetes simple for developers
The document discusses simplifying Kubernetes for developers, highlighting the use of Docker, Kompose, and Opencompose for managing containerized applications. It outlines the limitations of Docker Compose in Kubernetes environments and introduces Kompose as a tool for generating Kubernetes configurations, while also presenting Opencompose as a declarative abstraction for Kubernetes resources aimed at ease of use. Comparisons between Docker Compose, Kompose, and Opencompose are made, detailing how each tool addresses Kubernetes deployment challenges.
Making kubernetes simple for developers
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- 2. About me: ●Works for Red Hat in Developer Tools team ● Contributes to Kompose, OpenCompose, Kubernetes, OpenShift, etc. ● IRC, slack - surajd ● Twitter - surajd_ ● Github - surajssd ● Email - surajd.service@gmail.com
- 3. This talk isgoing to have a lot of references to Kubernetes or OpenShift and Docker Compose. Disclaimer
- 4. Story of today’sdeveloper (YMMV)
- 5. Deploy application incontainers
- 6. Learn docker* * Nowcalled moby
- 7. How do Irun “stuff” with docker? $ docker run hello-world $ docker run -p 5432:5432 postgres First steps with Docker
- 8. Code is localpython application: (venv) $ ls myapp.py requirements.txt (venv) $ python myapp.py
- 9. What do youneed to package your application? ● A Dockerfile, here I am copying code from my machine to the container doing builds locally. FROM centos RUN yum install -y python-pip3 COPY . /code WORKDIR /code RUN cd /code && pip install -r requirements.txt CMD [ “myapp” ] ● And few commands Note: Don’t try this in production :p
- 10. My code repo... $ ls Dockerfile myapp.py README.md requirements.txt
- 11. Run my awesomeapplication $ docker build -t myapp . $ docker run -p 8080:8080 myapp $ curl localhost:8080
- 12. Need to addone more service $ ls apiserver.py Dockerfile.apiserver Dockerfile.myapp myapp.py README.md requirements.txt
- 13. And to bringthis all up $ docker build -t myapp -f Dockerfile.myapp . $ docker build -t apiserver -f Dockerfile.apiserver . $ docker run postgres $ docker run apiserver $ docker run -p 8080:8080 myapp $ curl localhost:8080
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- 15. I write everythingin a docker-compose file, which looks like this: services: postgresql: image: postgresql apiserver: build: Dockerfile.apiserver env: POSTGRESQL_HOST: postgresql myapp: build: Dockerfile.myapp
- 16. Updated code repo... $ ls apiserver.py docker-compose.yml Dockerfile.apiserver Dockerfile.myapp myapp.py README.md requirements.txt
- 17. $ docker-compose up $curl localhost:8080
- 18. Docker-compose is easierfor development I am happy (Not for long).
- 19. Now that everythingis running locally, how and where do I deploy this?
- 20. Container orchestrators ● Kubernetes( OpenShift ) ● Docker Swarm ● Mesos
- 21. ● Docker ComposeI can use with Docker Swarm only ● Cannot use the docker-compose as is with swarm
- 22. ● Kubernetes isrobust ● Has Google’s production experience of more than a decade ● Huge contributor base and community
- 23. So what isthis Kubernetes?
- 25. ● Lot ofnew concepts for someone new in this world ● Pods, Service, Deployment, ReplicaSets etc. ● And what happened to all the investment I made with Docker Compose?
- 26. services: postgresql: image: postgresql apiserver: build: Dockerfile.apiserver env: POSTGRESQL_HOST:postgresql myapp: build: Dockerfile.myapp Remember this?
- 27. More google search Iwant to make my life easier
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- 31. Kompose helps mewith ● Generating Kubernetes configurations. ● Defaults generated by Kompose are good enough. ● Kompose helps as long as the Docker Compose syntax helps ● But we don’t stop at good enough, do we? :)
- 32. ● Works aslong as I have fewer services and generic use cases. ● My application is now more than just application and database containers.
- 33. Use cases wherekompose cannot do anything: ● Define service type. ● Kubernetes Jobs ● Secrets and Configmaps cannot be defined. ● Difficult to define volumes info. ● No way to define liveness probes and readiness probes ● How to club multiple containers in single pod ● Generating openshift templates directly.
- 34. ● Most ofthe things (from previous slide) can be done, but needs changes in docker-compose.yaml ● May not break application.
- 35. ● No directmapping to any docker-compose constructs ● Kompose exploits docker-compose restart. Kubernetes Jobs
- 36. Secrets and Configmaps ●No direct mapping to any docker-compose constructs ● But other ways of doing it. service: foo: Env: SECRET: devenv service: foo: Env: SECRET: prodenv
- 37. Volumes ● Kompose assumessome size for PVC
- 38. Ingress and Routes ●No direct mapping in docker-compose world ● Hack around with labels : labels: kompose.service.expose: "counter.example.com"
- 39. Liveness probe andReadiness probe ● No equivalent concept in docker-compose
- 40. Kubernetes Service type ●Here also there is no direct mapping in docker-compose world to do so. ● More hacking with labels : labels: kompose.service.type: nodeport
- 41. So what doI do to get around it? ● Generate configs with Kompose ● Edit configs yourself to fill in the gaps
- 42. kind: List apiVersion: v1 metadata:{} items: - kind: Service apiVersion: v1 metadata: name: etherpad creationTimestamp: labels: service: etherpad spec: ports: - name: '80' protocol: TCP port: 80 targetPort: 9001 selector: service: etherpad status: loadBalancer: {} - kind: Service apiVersion: v1 metadata: name: mariadb creationTimestamp: labels: service: mariadb spec: ports: - name: '3306' protocol: TCP port: 3306 targetPort: 3306 selector: service: mariadb status: loadBalancer: {} - kind: Deployment apiVersion: extensions/v1beta1 metadata: name: etherpad creationTimestamp: spec: replicas: 1 template: metadata: creationTimestamp: labels: service: etherpad spec: containers: - name: etherpad image: centos/etherpad ports: - containerPort: 9001 protocol: TCP env: - name: DB_DBID value: etherpad - name: DB_HOST value: mariadb - name: DB_PASS value: etherpad - name: DB_PORT value: '3306' - name: DB_USER value: etherpad resources: {} restartPolicy: Always strategy: {} status: {} - kind: Deployment apiVersion: extensions/v1beta1 metadata: name: mariadb creationTimestamp: spec: replicas: 1 template: metadata: creationTimestamp: labels: service: mariadb spec: volumes: - name: mariadb-claim0 persistentVolumeClaim: claimName: mariadb-claim0 containers: - name: mariadb image: centos/mariadb ports: - containerPort: 3306 protocol: TCP env: - name: MYSQL_DATABASE value: etherpad - name: MYSQL_PASSWORD value: etherpad - name: MYSQL_ROOT_PASSWORD value: etherpad - name: MYSQL_USER value: etherpad resources: {} volumeMounts: - name: mariadb-claim0 mountPath: "/var/lib/mysql" restartPolicy: Always
- 43. As a komposedeveloper ... ● It’s tempting to extend docker-compose, which is done right now with labels. ● Need to build a solution that overcomes docker-compose limitations with respect to Kubernetes
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- 46. What is OpenCompose? ●OpenCompose is a declarative higher level abstraction for specific Kubernetes resources. ● Simple for developers to comprehend use it in their day to day development workflow. ● Kubernetes resources define how to deploy an application, OpenCompose tries to stick to define application only.
- 47. Sample OpenCompose file version:'0.1-dev' services: - name: database replicas: 2 containers: - image: mariadb:10 env: - MYSQL_ROOT_PASSWORD=rootpasswd - MYSQL_DATABASE=wordpress - MYSQL_USER=wordpress - MYSQL_PASSWORD=wordpress ports: - port: 3306 - name: web containers: - image: wordpress:4 env: - WORDPRESS_DB_HOST=database:3306 - WORDPRESS_DB_PASSWORD=wordpress - WORDPRESS_DB_USER=wordpress - WORDPRESS_DB_NAME=wordpress ports: - port: 80 type: external
- 48. Running opencompose tool $opencompose convert -f wordpress.yaml created file "database-service.yaml" created file "database-deployment.yaml" created file "web-service.yaml" created file "web-deployment.yaml" $ kubectl create -f .
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- 50. Kollaborating with Kubernetescommunity
- 51. Comparison of allthree tools Feature docker-compose Kompose OpenCompose Define k8s service type - Using docker-compose labels. Define type under port Kubernetes Jobs - Using docker-compose restart - Secrets - - Define a secret Volumes Cannot define size Creates a pvc of 100MB Well defined data structure for volumes Liveness and Readiness - - Define health Multiple containers in one Pod - - Define container list under each service
- 52. References: ● Kompose http://kompose.io/ ●OpenCompose https://github.com/redhat-developer/opencompose/
- 53. Meetup ● Upcoming meetupbit.ly/k8s101 ● Meetup Page bit.ly/meetupk8s