Minimum Viable Kubernetes

A talk from SoCal Linux Expo 2023 Kubernetes Community Day

Transcript

1. Minimum Viable Kubernetes Noah Kantrowitz - coderanger.net - March 10, 2023 SCaLE Kubernetes Community Day 2023 1
2. NOAH KANTROWITZ » He/him » coderanger.net | cloudisland.nz/@coderanger » Kubernetes (ContribEx) and Python (webmaster@) » SRE/Platform for Geomagical Labs, part of IKEA » We do CV/AR for the home SCaLE Kubernetes Community Day 2023 2
3. WHAT IS KUBERNETES? “An open-source system for automating deployment, scaling, and management of containerized applications.” SCaLE Kubernetes Community Day 2023 3
4. YES BUT ACTUALLY NO SCaLE Kubernetes Community Day 2023 4
5. KUBERNETES AS AN API » POSIX - 1988 - Unix-like OS functions » CFEngine - 1993 - Desired state configuration » Puppet/Chef/Salt/Ansible - 2005-2012 - More! » Terraform - 2014 - Same but for infra » Kubernetes - 2014 - All of the above SCaLE Kubernetes Community Day 2023 5
6. GET /apis/v1/namespaces/default/pods SCaLE Kubernetes Community Day 2023 6
7. MODULARITY » Tool A cares about load balancers » Tool B also cares about load balancers » A and B don't have to know about each other SCaLE Kubernetes Community Day 2023 7
8. SHOULD I USE IT? SCaLE Kubernetes Community Day 2023 8
9. SHOULD I USE IT? “Only for big and/or complex systems with lots of microservices and lots of developers and [insert more marketing buzzwords here].” SCaLE Kubernetes Community Day 2023 9
10. SHOULD I USE IT? “Only for big and/or complex systems with lots of microservices and lots of developers and [insert more marketing buzzwords here].” Yes! (Probably!) SCaLE Kubernetes Community Day 2023 10
11. WHY NOT ...? » Docker? Not convergent itself SCaLE Kubernetes Community Day 2023 11
12. WHY NOT ...? » Docker? Not convergent itself » Docker Compose? Tricky for remote use, not extensible SCaLE Kubernetes Community Day 2023 12
13. WHY NOT ...? » Docker? Not convergent itself » Docker Compose? Tricky for remote use, not extensible » Ansible/Terraform? Intermittent convergence SCaLE Kubernetes Community Day 2023 13
14. WHY NOT ...? » Docker? Not convergent itself » Docker Compose? Tricky for remote use, not extensible » Ansible/Terraform? Intermittent convergence » ECS/Fargate/Cloud Run? Expensive, vendor lock-in SCaLE Kubernetes Community Day 2023 14
15. WHY NOT ...? » Docker? Not convergent itself » Docker Compose? Tricky for remote use, not extensible » Ansible/Terraform? Intermittent convergence » ECS/Fargate/Cloud Run? Expensive, vendor lock-in » Lambda/FaaS? More lock-in and limited architecture SCaLE Kubernetes Community Day 2023 15
16. REALLY? » Room to grow is important » Prototypes are forever, we all know this » PaaS and FaaS platforms are high-quality but limited SCaLE Kubernetes Community Day 2023 16
17. DRAMATIS PERSONA » Small team, definitely single pizza » New monolith web app or 2-3 services » MVP or a small standalone product » No ops team, probably just one "full stack" team » Cost sensitive but not shoestring SCaLE Kubernetes Community Day 2023 17
18. WHY SHOULD I? » Start small but grow with your project » Huge ecosystem of tools » Modular design means you swap components later » High-level APIs let you code only what you care about » Avoid the future lift-and-shift SCaLE Kubernetes Community Day 2023 18
19. BUT HOW CAN I? “Isn't Kubernetes really hard?” SCaLE Kubernetes Community Day 2023 19
20. BUT HOW CAN I? “Isn't Kubernetes really hard?” It doesn't have to be! SCaLE Kubernetes Community Day 2023 20
21. TL;DW USE K3S » Friendly fork of Kubernetes, mini all-in-one installer » Curlbash for systemd or k3d for existing Docker » Defaults to SQLite for easy single-node » But supports Postgres and MySQL too » That VPS server you were going to use? Install k3s first SCaLE Kubernetes Community Day 2023 21
22. HOSTED OPTIONS? SCaLE Kubernetes Community Day 2023 22
23. 90% IS IGNORABLE » You need Deployments, Pods » And Services, Ingresses » No really, that's it SCaLE Kubernetes Community Day 2023 23
24. HOW TO GET STARTED » Do it however you would without Kubernetes » But on Kubernetes » Does the thing have Docker install instructions? Done » Is there a community Docker Hub image? Use it » Find a guide with apt-get install something? Copy that into a Dockerfile and roll with it SCaLE Kubernetes Community Day 2023 24
25. ASIDE: DOING THINGS POORLY IT'S OKAY! SCaLE Kubernetes Community Day 2023 25
26. THE TRIFECTA » Workloads - running stuff » Networking - connecting stuff » Storage - keeping stuff SCaLE Kubernetes Community Day 2023 26
27. WORKLOADS » Running stuff on your servers! » Pod == a running container somewhere » Yes Pods have a million more options but simple for now » Deployments == run N copies of a Pod » N is frequently 1, that's okay SCaLE Kubernetes Community Day 2023 27
28. WORKLOADS » StatefulSets? DaemonSets? Jobs? Later! » CronJobs? Maybe, if you need them » apt-get install cron works too! SCaLE Kubernetes Community Day 2023 28
29. KUBECTL RUN » YAML Engineering? » kubectl run redis --image=redis » --port 1234 - expose a port » --env "FOO=bar" - set environment variables » --replicas 5 - run multiple copies SCaLE Kubernetes Community Day 2023 29
30. MINIMUM VIABLE MANIFESTS apiVersion: apps/v1 kind: Deployment metadata: name: myapp SCaLE Kubernetes Community Day 2023 30
31. MINIMUM VIABLE MANIFESTS spec: selector: matchLabels: app: myapp template: metadata: labels: app: myapp SCaLE Kubernetes Community Day 2023 31
32. MINIMUM VIABLE MANIFESTS apiVersion: apps/v1 kind: Deployment metadata: name: myapp spec: selector: matchLabels: app: myapp template: metadata: labels: app: myapp spec: containers: - name: myapp image: mycompany/myapp:v1.2.3 SCaLE Kubernetes Community Day 2023 32
33. MINIMUM +1 containers: - name: myapp image: mycompany/myapp:v1.2.3 command: ["python", "main.py"] env: - name: PASSWORD value: secret SCaLE Kubernetes Community Day 2023 33
34. NETWORKS! » Inside vs Outside » Inside -> Inside - easy, flat network, just need DNS » Inside -> Outside - outgoing traffic, default allow » Outside -> Inside - the spicy one SCaLE Kubernetes Community Day 2023 34
35. INTERNAL NETWORK » Flat network, don't ask how » Do you care what a CNI is? NOPE! » Everything is open but dynamic IPs » Need DNS to help things find each other SCaLE Kubernetes Community Day 2023 35
36. SERVICES apiVersion: v1 kind: Service metadata: name: myapp spec: selector: app: myapp ports: - port: 8000 SCaLE Kubernetes Community Day 2023 36
37. POKING HOLES » Ingress - HTTP(S), you already have it » Load Balancer - any TCP/UDP port, cloud vs. on-prem » Node Port - works anywhere, weird, avoid SCaLE Kubernetes Community Day 2023 37
38. INGRESS apiVersion: networking.k8s.io/v1 kind: Ingress metadata: name: myapp spec: rules: - host: example.com http: paths: - path: / pathType: Prefix backend: service: name: myapp port: number: 8000 SCaLE Kubernetes Community Day 2023 38
39. GETTING THE IP $ kubectl describe ingress myapp Name: myapp Address: 40.155.110.208 ... SCaLE Kubernetes Community Day 2023 39
40. SERVICE MESH? SCaLE Kubernetes Community Day 2023 40
41. DATA DATA EVERYWHERE BUT NOT A DROP TO DRINK SCaLE Kubernetes Community Day 2023 41
42. STORAGE OPTIONS » Don't - hosted databases, object storage » Host files - store things in a folder, like we used to » Cloud volumes - what the vendor wants you to use SCaLE Kubernetes Community Day 2023 42
43. HOST PATH containers: - name: postgres image: postgres volumeMounts: - path: /var/lib/postgresql/data name: data volumes: - name: data hostPath: path: /pgdata SCaLE Kubernetes Community Day 2023 43
44. MORE SERVERS, MORE PROBLEMS containers: - name: postgres image: postgres nodeName: mynode1 $ kubectl get nodes SCaLE Kubernetes Community Day 2023 44
45. PERSISTENT VOLUMES apiVersion: v1 kind: PersistentVolumeClaim metadata: name: myapp-storage spec: accessModes: - ReadWriteOnce storageClassName: local-path resources: requests: storage: 50Gi SCaLE Kubernetes Community Day 2023 45
46. USING A CLAIM containers: - name: postgres image: postgres volumeMounts: - path: /var/lib/postgresql/data name: data volumes: - name: data persistentVolumeClaim: claimName: myapp-storage SCaLE Kubernetes Community Day 2023 46
47. CLOUD VOLUMES » CSI - container storage interface » There's a lot of cloud and storage vendors » Take the problem and push it somewhere else » Vendors can own their plugin » Cloud controllers? SCaLE Kubernetes Community Day 2023 47
48. NON-CLOUD CLOUD » Longhorn » Rook? (Ceph) » OpenEBS? » Lots more SCaLE Kubernetes Community Day 2023 48
49. KUBECTL ROUND 2: FIGHT » kubectl apply - the important one » kubectl get <type> - list things » kubectl describe <type> - show details » kubectl delete <type> - what it sounds like SCaLE Kubernetes Community Day 2023 49
50. kubectl apply -f SCaLE Kubernetes Community Day 2023 50
51. KUBECTL <VERB> <TYPE> [<NAME>] » kubectl get pods - list all pods » kubectl get service myapp - list a single service » kubectl describe service myapp - details on one » kubectl delete pod myapp-5d5d5fc579-6kl82 » kubectl delete -f myapp.yaml SCaLE Kubernetes Community Day 2023 51
52. WHAT I'VE LEFT OUT A lot! SCaLE Kubernetes Community Day 2023 52
53. THE USUAL SUSPECTS » Multi-server availability (Pod anti-affinities) » Secrets management (Secrets, sealed-secrets) » Access control (RBAC) » Monitoring and alertings (Prometheus and Grafana) SCaLE Kubernetes Community Day 2023 53
54. WHAT ABOUT THE FANCY FEATURES? SCaLE Kubernetes Community Day 2023 54
55. START SMALL GROW AS NEEDED SWAP COMPONENTS NEVER STOP LEARNING SCaLE Kubernetes Community Day 2023 55
56. I'M HIRING - ML OPS MORE INFO AT GEOMAGICAL.COM SCaLE Kubernetes Community Day 2023 56
57. THANK YOU QUESTIONS? SCaLE Kubernetes Community Day 2023 57
58. » Intro » What is Kubernetes » Is it all just hype? No » Systems as APIs » POSIX » Salt/Ansible/Chef/Puppet » Kubernetes SCaLE Kubernetes Community Day 2023 58