Journey to deploying rails on Kubernetes

Transcript

1. Journey to Deploying Rails on Kubernetes Rahul Mahale. BigBinary
2. $whoami • Works @ BigBinary • A FOSS Enthusiastic • Shipping Containers to Production @Rahul_Mahale
3. Agenda • Walk you through how we deployed our production application on Kubernetes.
4. Two Grounds • Provisioning production ready k8s cluster • Deploying Ruby on Rails application on k8s cluster
5. K8s production cluster should be • Highly available. • Behind VPN(Secured Networking) • Auto-Scalable
6. How to ? • Provision HA cluster using Kops, Kubeadm • Private networking using Calico/weave/flannel • Use Cluster-autoscaler k8s addon
7. Rails deployment flow • Deploy a new code-base on each subsequent deployment. • Build an image • Push it to docker registry(dockerhub,quay,self hosted) • Pull the image and deploy change with zero down time.
8. Rails deployment flow • Update configuration rake task • rake assets:precompile • rake db:create or db:migrate • rake db:seed • Update jobs/cronjobs • restart the services.
9. Image building • Automatic image building using. ➔ Dockerhub/dockercloud ➔ Quay.io ➔ ECS ➔ Self-hosted Jenkins
10. Kubernetes terminologies • Deployments • Services • Configmaps • Secrets • Jobs • Scheduled Jobs
11. Where to host database ? • On kubernetes ? At your own risk. • We host our DB on AWS RDS and on k8s using PVC • Pre-created on launch of the new application.
12. K8s isolation • App running with app server like unicorn/puma • Web server to serve the app like nginx • Load balancer configured it with domain. • Background jobs like Sidekiq/Delayed Job. • Cron jobs. • Custom rake tasks
13. How things happen • Create namespace, secrets etc. • App deployment with app server unicorn • Deployment with nginx • Deployment for background job • Service for each deployment • Fetch database configuration from configmap • Fetch sidekiq from configmap. • Create jobs/cronjobs
14. Production things • Separate namespace for each app • Label nodes • ABAC/RBAC mode to distribute kubectl configuration with devs. • Specify resources limit.
15. Zero downtime deployment • Healthcheck • Rediness probe
16. Autoscaling of app • Horizontal pod auto-scaler(HPA) • Memory based auto-scaler(own)
17. Jobs Use it for custom tasks
18. Scheduled Jobs • Need to restart api server for enabling it with --runtime-config=batch/v2alpha1 • Restart policy, restartPolicy: OnFailure • Runs our Cron Jobs • We are coming up with our own tool for parsing whenever cron to k8s cronjobs
19. Known issues • Issue #42164 ➔ Restart docker or terminate node • Pods with PVCs doesnt scale ➔ you should check Statefulset
20. Monitoring • Cluster monitoring using Prometheus and Grafana • Configure Prometheus alerts to notify on slack/email etc.
21. Logging • ELK addon from Kubernetes
22. Automation • Create artifacts using something likke Ansible or your own tool, create database, secrets etc. ➔ Creates deployment templates. • Helm is good tool from k8s community. • kubectl or k8s API • Label nodes script
23. Backup of Cluster • Etcd is heart of the k8s cluster. • Consider backing it up using something like reshifter. https://github.com/mhausenblas/reshifter
24. Don't forget • Kubeval • Kubernetes-dashboard • Heapster • kube-state-metrics etc. https://github.com/garethr/kubeval
25. Links • http://kubernetes.io/docs/ • http://blog.bigbinary.com/ • http://github.com/kubernetes/kops/