Kubernetes and the Potential for Higher Level Interfaces

Talk from KubeCon, the Kubernetes community conference. Covering the importance of context for user interfaces, standards, platforms, ecosystems, APIs and examples of high-level user interfaces for Kubernetes.

Transcript

1. Kubernetes and the Potential for Higher Level Interfaces Puppet Labs Gareth Rushgrove Ecosystems, APIs and user needs
2. Gareth Rushgrove @garethr
3. Gareth Rushgrove
4. Human and computer interfaces Concepts and demos Ecosystems and interoperability Gareth Rushgrove - - -
5. The User Interface(s) of Kubernetes What do we mean by user and interface?
6. The user context matters Gareth Rushgrove
7. Creating Consuming Gareth Rushgrove - -
8. Developers Operators Gareth Rushgrove - -
9. Building something new Running in production Gareth Rushgrove - -
10. Team size Regulation/compliance Multi-tenancy Infrastructure size Skills and experience Gareth Rushgrove - - - - -
11. Gareth Rushgrove Gareth Rushgrove
12. kubectl is a user interface Gareth Rushgrove
13. YAML is a user interface Gareth Rushgrove
14. Gareth Rushgrove Dashboard is a user interface Gareth Rushgrove
15. The API is a user interface Gareth Rushgrove
16. Client libraries are a user interface Gareth Rushgrove
17. Different interfaces are useful in different contexts Gareth Rushgrove
18. Different people might use different interfaces to achieve different tasks Gareth Rushgrove
19. Out of the box Just enough user interface
20. kubectl Gareth Rushgrove
21. $ kubectl controls the Kubernetes cluster manager. Find more information at https://github.com/kubernetes/kubernetes. Usage: kubectl [flags] kubectl [command] Available Commands: get Display one or many resources describe Show details of a specific resource or group of resources create Create a resource by filename or stdin replace Replace a resource by filename or stdin. patch Update field(s) of a resource by stdin. delete Delete resources by filenames, stdin, resources and names, or by resources and label selector. edit Edit a resource on the server A universal interface for actions on a Kubernetes cluster Gareth Rushgrove
22. Gareth Rushgrove
23. YAML Gareth Rushgrove
24. template: metadata: labels: app: guestbook tier: frontend spec: containers: - name: php-redis image: gcr.io/google_samples/gb-frontend:v4 resources: requests: cpu: 100m memory: 100Mi env: - name: GET_HOSTS_FROM value: dns # If your cluster config does not include a dns service, then to A data format describing desired state Gareth Rushgrove
25. API wire format as user interface Gareth Rushgrove
26. But isn’t YAML declarative? And other user interface tales
27. Yes Gareth Rushgrove
28. Code plus data has advantages over data alone Gareth Rushgrove
29. The language to represent the data should be a simple, data-only format such as JSON or YAML, and programmatic modification of this data should be done in a real programming language Gareth Rushgrove Borg, Omega, and Kubernetes, ACM Queue, Volume 14, issue 1 http://queue.acm.org/detail.cfm?id=2898444 “
30. Avoid repetition Combine external inputs Correctness Abstractions Gareth Rushgrove - - - -
31. So why are so many people hand writing YAML? Gareth Rushgrove
32. Changes with kubectle patch diverge from the model $ kubectl patch --help Update field(s) of a resource using strategic merge patch JSON and YAML formats are accepted. Usage: kubectl patch (-f FILENAME | TYPE NAME) -p PATCH [flags] Examples: # Partially update a node using strategic merge patch kubectl patch node k8s-node-1 -p '{"spec":{"unschedulable":true}}' Gareth Rushgrove
33. $ kubectl apply --help Apply a configuration to a resource by filename or stdin. JSON and YAML formats are accepted. Usage: kubectl apply -f FILENAME [flags] Examples: # Apply the configuration in pod.json to a pod. $ kubectl apply -f ./pod.json And kubectl apply requires the full object serialisation Gareth Rushgrove
34. A familiar Kubernetes Pod definition in YAML Gareth Rushgrove
35. What happens if you run the same YAML file twice? Gareth Rushgrove
36. How many times do you have to repeat the same label? Gareth Rushgrove
37. kubectl is actually pretty low-level Gareth Rushgrove
38. kubectl get pod mypod -o yaml \ | sed 's/\(image: myimage\):.*$/\1:v4/' \ | kubectl replace -f - This is from the official kubectl help. It pipes to sed. Gareth Rushgrove
39. Declarative code with an idempotent runtime model Gareth Rushgrove
40. Describe what you want Gareth Rushgrove
41. Converge from any state Gareth Rushgrove
42. The same Kubernetes Pod described in Puppet Gareth Rushgrove
43. $ puppet apply examples/init.pp --test Info: Loading facts Notice: Compiled catalog for gareths in environment production in 1.24 seconds Info: Applying configuration version '1453298602' Info: Checking if sample-pod exists Info: Creating kubernetes_pod sample-pod Notice: /Stage[main]/Main/Kubernetes_pod[sample-pod]/ensure: created Notice: Applied catalog in 0.23 seconds Running without that Pod already existing will create it Gareth Rushgrove
44. Running a second time, nothing changes because the Pod already exists Gareth Rushgrove $ puppet apply examples/init.pp --test Info: Loading facts Notice: Compiled catalog for garethr in environment production in 1.33 seconds Info: Applying configuration version '1453298688' Info: Checking if sample-pod exists Notice: Applied catalog in 0.15 seconds
45. $ puppet resource kubernetes_pod sample-pod kubernetes_pod { 'sample-pod': ensure => 'present', metadata => { 'creationTimestamp' => '2016-01-20T14:03:23Z', 'name' => 'sample-pod', 'namespace' => 'default', 'resourceVersion' => '4579', 'selfLink' => '/api/v1/namespaces/default/pods/sample-pod’, 'uid' => '91c8a550-bf7e-11e5-816e-42010af001b1' }, spec => { 'containers' => [{ ‘image' => 'nginx', 'imagePullPolicy' => 'IfNotPresent', 'name' => ‘container-name', 'resources' => {'requests' => {'cpu' => '100m'}}, 'terminationMessagePat [{'mountPath' => '/var/run/secrets/kubernetes.io/serviceaccount', 'name' 'dnsPolicy' => 'ClusterFirst', 'nodeName' => 'gke-guestbook-dc15a31a-nod puppet resource allows for interrogating an existing Kubernetes installation Gareth Rushgrove
46. $ kubectl describe pod sample-pod Name: sample-pod Namespace: default Image(s): nginx Node: gke-guestbook-dc15a31a-node-fyb6/10.240. Start Time: Wed, 20 Jan 2016 14:03:23 +0000 Labels: <none> Status: Running Reason: Message: IP: 10.24.1.7 Replication Controllers: <none> Containers: container-name: Container ID: docker://542389c5b2a98616ba3a8001029bc4a3f00d7c0 Image: nginx Image ID: docker://407195ab8b07 The same information is still accessible via other tooling Gareth Rushgrove
47. Other programming languages exist Gareth Rushgrove
48. DEMO
49. Gareth Rushgrove More details on the official Kubernetes blog Gareth Rushgrove
50. Imperative Interfaces Pragmatism and familiarity
51. Gareth Rushgrove
52. Gareth Rushgrove Deis is an open source PaaS that provides a Heroku- inspired workflow, using Kubernetes under the hood Gareth Rushgrove
53. Interactive CLI to login Gareth Rushgrove $ deis login http://deis.example.com username: deis password: Logged in as deis
54. Create configs locally with the CLI Gareth Rushgrove $ deis create Creating application... done, created boring-huntress Git remote deis added
55. $ git push deis master Counting objects: 95, done. Delta compression using up to 8 threads. Compressing objects: 100% (52/52), done. Writing objects: 100% (95/95), 20.24 KiB | 0 bytes/s, done. Total 95 (delta 41), reused 85 (delta 37) -----> Ruby app detected -----> Compiling Ruby/Rack -----> Using Ruby version: ruby-1.9.3 -----> Installing dependencies using 1.5.2 Running: bundle install --without development:test --path vendor/bundle --binstubs vendor/bundle/bin -j4 --deployment Fetching gem metadata from http://rubygems.org/.......... Fetching additional metadata from http://rubygems.org/.. Using bundler (1.5.2) Installing tilt (1.3.6) Installing rack (1.5.2) The switch to Git for deployment Gareth Rushgrove
56. Set config using CLI Gareth Rushgrove $ deis config:set FOO=1 BAR=baz && deis config:pull $ cat .env FOO=1 BAR=baz $ echo "TIDE=high" >> .env $ deis config:push Creating config... done, v4 === yuppie-earthman DEIS_APP: yuppie-earthman FOO: 1 BAR: baz TIDE: high
57. $ deis scale web=8 Scaling processes... but first, coffee! done in 20s === boring-huntress Processes --- web: web.1 up (v2) web.2 up (v2) web.3 up (v2) web.4 up (v2) web.5 up (v2) web.6 up (v2) web.7 up (v2) web.8 up (v2) Scale using the CLI Gareth Rushgrove
58. Replication Controllers, Services and Pods are implementation details Gareth Rushgrove
59. Kubernetes is an implementation details from the point of view of the user Gareth Rushgrove
60. Kubernetes is NOT an implementation details from the point of view of the administrator Gareth Rushgrove
61. The advantages of familiarity Gareth Rushgrove
62. The challenges of git as a user interface Gareth Rushgrove
63. Ecosystems and Interoperability Everyone can play together
64. Gareth Rushgrove
65. Package management Gareth Rushgrove
66. Gareth Rushgrove Helm, a package manager for Kubernetes Gareth Rushgrove
67. $ helm install redis-cluster ---> Running `kubectl create -f` ... services/redis-sentinel pods/redis-master replicationcontrollers/redis replicationcontrollers/redis-sentinel ---> Done Help provides distribution tools, plus wraps kubectl Gareth Rushgrove
68. Helm as a user interface Gareth Rushgrove
69. Gareth Rushgrove Charts as a place to share low level descriptions Gareth Rushgrove
70. name: jenkins home: https://jenkins-ci.org/ version: 0.2.0 description: The leading open-source continuous integration server. maintainers: - Matt Fisher <mfisher@deis.com> details: Jenkins is the leading open-source continuous integration server. Chart.yaml metadata format Gareth Rushgrove
71. Gareth Rushgrove Or, what is the Kubernetes equivalent to MPM metadata? Gareth Rushgrove
72. The importance of sharing metadata Gareth Rushgrove
73. Metadata as a first class user interface Gareth Rushgrove
74. If the API is the point of interoperability, how can it evolve safely? Gareth Rushgrove
75. Gareth Rushgrove Swagger is a specification for describing APIs Gareth Rushgrove
76. Gareth Rushgrove Now being developed by the Open API Initiative Gareth Rushgrove
77. "type": "integer", "format": "int32", "description": "The port on each node on which this service is exposed when type=NodePort or LoadBalancer. Usually assigned by the system. If specified, it will be allocated to the service if unused or else creation of the service will fail. Default is to auto-allocate a port if the ServiceType of this Service requires one. More info: http://releases.k8s.io/HEAD/docs/user- guide/services.md#type--nodeport" } } }, "v1.ServiceStatus": { "id": "v1.ServiceStatus", "description": "ServiceStatus represents the current status of a service.", "properties": { "loadBalancer": { "$ref": "v1.LoadBalancerStatus", "description": "LoadBalancer contains the current status of the load-balancer, if one is present." The Kubernetes API spec is ~14,000 lines of JSON Gareth Rushgrove
78. Some client libraries, including the Puppet module, are generated from the Swagger spec Gareth Rushgrove
79. Gareth Rushgrove
80. Standards mean going slow in the right places Gareth Rushgrove
81. So we can go fast everywhere else Gareth Rushgrove
82. Conclusions Why Kubernetes as a platform
83. Interoperable because of a stable set of APIs Gareth Rushgrove
84. Platforms exposing high level interfaces, without limiting access to lower level ones Gareth Rushgrove
85. Allow for different use-cases and different life-cycles on the same infrastructure Gareth Rushgrove
86. Questions? And thanks for listening