Kubernetes without the YAML

A lightning talk from the Kubernetes dev room at Configuration Management Camp 2017. Discussion of higher level programatic interfaces and tools for Kubernetes.

Transcript

1. (without introducing more risk)
   Kubernetes without
   the YAML
   Puppet
   Gareth Rushgrove
   Alternative configuration options for K8
   

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2. (without introducing more risk)
   @garethr
   

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3. (without introducing more risk)
   Gareth Rushgrove
   

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4. (without introducing more risk)
   What we’ll cover
   This talk
   

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5. - Why not (only) YAML
   - A quick look at some alternatives
   - Short discussion
   Gareth Rushgrove
   

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6. (without introducing more risk)
   The argument
   Why not (only) YAML
   

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7. Gareth Rushgrove
   Brian Grant, Google, Kubernetes Config SIG
   “We've had a few complaints that YAML is
   ugly, error prone, hard to read, etc. Are
   there any other alternatives we might want
   to support?
   

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8. (without introducing more risk)
   Gareth Rushgrove
   API wire format as user interface
   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:
   

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9. 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
   “
   

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10. - Avoid repetition
    - Combine external inputs
    - Enforce correctness
    - Introduce abstractions
    Gareth Rushgrove
    

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11. (without introducing more risk)
    Configuration language for JSON data
    Jsonnet
    

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12. (without introducing more risk)
    jsonnet.org
    

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13. (without introducing more risk)
    Gareth Rushgrove
    Jonnet template
    // Example template
    {
    person1: {
    name: "Alice",
    welcome: "Hello " + self.name + "!",
    },
    person2: self.person1 { name: "Bob" },
    }
    

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14. (without introducing more risk)
    Gareth Rushgrove
    Render templates
    $ jsonnet example.jsonnet
    {
    "person1": {
    "name": "Alice",
    "welcome": "Hello Alice!"
    },
    "person2": {
    "name": "Bob",
    "welcome": "Hello Bob!"
    }
    }
    

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15. (without introducing more risk)
    kubernetes examples
    

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16. (without introducing more risk)
    kubernetes-anywhere
    

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17. (without introducing more risk)
    Gareth Rushgrove
    Jsonnet functions
    function(cfg)
    local if_enabled(addon, manifest) = if cfg.phase3[addon] then manifest
    local join(arr) = std.foldl(function(a, b) a + b, arr, {});
    if_enabled("run_addons",
    join([
    if_enabled("kube_proxy", (import "kube-proxy/kube-proxy.jsonnet"
    if_enabled("dashboard", (import "dashboard/dashboard.jsonnet")(c
    if_enabled("heapster", (import "heapster/heapster.jsonnet")(cfg)
    if_enabled("kube_dns", (import "kube-dns/kube-dns.jsonnet")(cfg)
    ]))
    

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18. (without introducing more risk)
    A REPL for Kubernetes
    Kubeplay
    

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19. (without introducing more risk)
    errordeveloper/kubeplay
    

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20. (without introducing more risk)
    Gareth Rushgrove
    A REPL for Kubernetes
    $ ./kubeplay
    kubeplay (namespace="*")> pods # list pods in the cluster
    
    kubeplay (namespace="*")> @pod = _.any # pick a random pod from the list
    kubeplay (namespace="*")> puts @pod.to_json # output the pod definition
    {
    "metadata": {
    ...
    },
    "spec": {
    ...
    "containers": [
    {
    

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21. (without introducing more risk)
    Gareth Rushgrove
    Ruby based DSL
    @metadata = replicasets("*/").to_ruby.items.map do |k,v|
    v.metadata
    end
    @metadata.each do |i|
    puts "Name:\t#{i.name}"
    puts "Labels:\t#{i.labels}"
    puts
    end
    

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22. (without introducing more risk)
    Declarative Domain Specific Language
    Puppet
    

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23. (without introducing more risk)
    garethr/garethr-kubernetes
    

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24. (without introducing more risk)
    Gareth Rushgrove
    Puppet DSL
    kubernetes_pod { 'sample-pod':
    ensure => present,
    metadata => {
    namespace => 'default',
    },
    spec => {
    containers => [{
    name => 'container-name',
    image => 'nginx',
    }]
    },
    }
    

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25. (without introducing more risk)
    Gareth Rushgrove
    Query existing resources
    $ 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',
    

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26. (without introducing more risk)
    More Domain Specific Language
    Terraform
    

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27. (without introducing more risk)
    maxmanuylov/terraform-provider-kubernetes
    

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28. (without introducing more risk)
    Gareth Rushgrove
    Terraform provider
    resource "kubernetes_resource" "mypod" {
    # Required, must link on the corresponding "kubernetes_cluster" data s
    cluster = "${data.kubernetes_cluster.main.cluster}"
    collection = "pods"
    name = "mypod"
    labels {
    a = "b"
    }
    }
    

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29. (without introducing more risk)
    If you’re interested in this topic
    One last thing
    

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30. (without introducing more risk)
    KubeCon BoF session
    

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31. (without introducing more risk)
    Questions?
    And thanks for listening
    

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