Writing Kubenetes tools in Go

Kubernetes Meetup Tokyo #2 http://k8sjp.connpass.com/event/33508/ の発表資料です

Transcript

1. Writing Kubernetes tools
   in Go
   
   ,VCFSOFUFT.FFUVQ5PLZP
   %BJTVLF'VKJUB!EUBO
   

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2. Daisuke Fujita
   @dtan4
   

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3. $ k8sec
   CLI tool to manage Kubernetes Secrets easily
   

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4. k8sec
   • Kubernetes Secret Λखܰʹ͍͡Δπʔϧ
   
   • Interface like Heroku CLI (heroku config)
   
   • Written in Go
   dtan4/k8sec
   $ k8sec \
   [--kubeconfig KUBECONFIG] \
   [--namespace NAMESPACE] \
   ARGS
   

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5. Why k8sec?
   • Secret ΛΞϓϦέʔγϣϯͷ؀ڥม਺ʹ࢖͍͍ͨ
   
   • kubectl Ͱ΍Δͱ໘౗ͩͬͨ
   
   • kubectl ͩͱҰൃͰ list, update Ͱ͖ͳ͍
   
   • Ұ౓ YAML ʹు͍ͯ replace
   http://kubernetes.io/docs/user-guide/secrets/#using-secrets-as-environment-variables
   $ kubectl create secret generic my-secret \
   --from-literal=key1=supersecret \
   --from-literal=key2=topsecret
   $ kubectl get secret registrykey -o json \
   | jq -r '.data[".dockercfg"]' | base64 -D
   

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6. k8sec
   $ k8sec list rails
   NAME TYPE KEY VALUE
   rails Opaque database-url "postgres://example.com:5432/dbname"
   # Show values as base64-encoded string
   $ k8sec list --base64 rails
   NAME TYPE KEY VALUE
   rails Opaque database-url cG9zdGdyZXM6Ly9leGFtcGxlLmNvbTo1NDMyL2RibmFtZQ==
   Ұཡදࣔ list
   
   dtan4/k8sec
   

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7. k8sec
   # Set secret
   $ k8sec set rails rails-env=production
   rails
   # Pass base64-encoded value
   $ echo dtan4 | base64
   ZHRhbjQK
   $ k8sec set --base64 rails foo=ZHRhbjQK
   rails
   $ k8sec list rails
   NAME TYPE KEY VALUE
   rails Opaque database-url "postgres://example.com:5432/dbname"
   rails Opaque foo "dtan4\n"
   # Unset secret
   $ k8sec unset rails rails-env
   ઃఆɺղআ set,unset
   
   dtan4/k8sec
   

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8. k8sec
   # Save as .env
   $ k8sec save -f .env rails
   $ cat .env
   database-url="postgres://example.com:5432/dbname"
   # Load .env
   $ k8sec load -f .env rails
   LFZWBMVFFOW load,save
   
   dtan4/k8sec
   

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9. Why k8sec?
   • Secret ΛΞϓϦέʔγϣϯͷ؀ڥม਺ʹ࢖͍͍ͨ
   
   • kubectl Ͱ΍Δͱ໘౗ͩͬͨ
   
   • kubectl ͩͱҰൃͰ list, update Ͱ͖ͳ͍
   
   • Ұ౓ YAML ʹు͍ͯ replace
   http://kubernetes.io/docs/user-guide/secrets/#using-secrets-as-environment-variables
   $ kubectl create secret generic my-secret \
   --from-literal=key1=supersecret \
   --from-literal=key2=topsecret
   $ kubectl get secret registrykey -o json \
   | jq -r '.data[".dockercfg"]' | base64 -D
   

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10. kubectl
    • ສೳʂ
    
    • API ΂ͬͨΓͳͷͰɺ࣮ӡ༻Ͱ͸࢖͍ʹ͍͘෦෼΋
    
    • ඇӡ༻ଆ (e.g. Rails developer) ͕৮Δʹ͸

    ֶशίετ͕ߴ͍…ʁ
    
    => ࣗ෼ͨͪͷཁٻʹదͨ͠ wrapper Λ࡞Ζ͏
    

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11. kubectl wrapper
    • ଞݴޠ͔Β kubectl ίϚϯυΛ௚઀ୟ͘ͷ͸

    εϚʔτ͡Όͳ͍
    
    • kubectl ͬͯཁ͢Δʹ 

    Kubernetes API ΫϥΠΞϯτͰ͢ΑͶ
    
    • ௚઀ API Λୟ͘Α͏ʹ͢Ε͹͍͍ͷͰ͸…ʁ
    

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12. Kubernetes API Client
    Library
    https://github.com/kubernetes/kubernetes/blob/master/docs/devel/client-libraries.md
    

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13. k8s.io/kubernetes/pkg/client
    Official Kubernetes API client library
    

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14. API ΫϥΠΞϯτ࡞੒
    loadingRules := clientcmd.NewDefaultClientConfigLoadingRules()
    loadingRules.ExplicitPath = clientcmd.RecommendedHomeFile
    loader := clientcmd.NewNonInteractiveDeferredLoadingClientConfig(loadingRules,
    &clientcmd.ConfigOverrides{})
    clientConfig, err := loader.ClientConfig()
    if err != nil {
    return nil, err
    }
    kubeClient, err := client.New(clientConfig)
    if err != nil {
    return nil, err
    }
    import (
    "k8s.io/kubernetes/pkg/api"
    client "k8s.io/kubernetes/pkg/client/unversioned"
    "k8s.io/kubernetes/pkg/client/unversioned/clientcmd"
    )
    

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15. API ΫϥΠΞϯτ࡞੒
    loadingRules.ExplicitPath = clientcmd.RecommendedHomeFile
    • loadingRules.ExplicitPath ʹ

    ίϯϑΟάϑΝΠϧͷύεΛࢦఆ
    
    • RecommendedHomeFile == ~/.kube/config
    https://github.com/kubernetes/kubernetes/blob/master/pkg/client/unversioned/clientcmd/loader.go
    

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16. API ݺͼग़͠
    pods, err :=
    kubeClient.Pods(api.NamespaceDefault).List(api.ListOptions{})
    • ·ͣ Pods, Secret ͷΑ͏ʹϦιʔεࢦఆ
    w Ҿ਺͸/BNFTQBDF
    • api.NamespaceDefault == "default"
    • api.NamespaceSystem == "system"
    w ϦιʔεʹνΣΠϯͯ͠ૢ࡞Λࢦఆ
    • Get(name), List
    kubeClient..
    https://github.com/kubernetes/kubernetes/blob/4a78db61370df83a37957490749f7d171b00c28a/pkg/api/types.go#L154-L161
    

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17. Pod ҰཡΛग़ྗ
    for _, pod := range pods.Items {
    fmt.Println(pod.Name)
    }
    hello-world-e2d3x
    wordpress-mysql-488205646-t6v4k
    

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18. ஫ҙ
    • k8s.io/kubernetes ͸ Kubernetes ຊମͷϦϙδτϦ
    ͳͷͰɺͰ͔ͯ͘ॏ͍ (400 Mbyte ~)
    
    • github.com/docker/docker ΋ґଘͯ͠Δ
    
    • Godeps Έ͍ͨʹ vendoring ΛϦϙδτϦʹؚΊΔ

    ৔߹͸ཁ஫ҙ
    
    • glide ࢖͓͏
    
    • kubectl ͷιʔε (pkg/kubectl) Λಡ΋͏
    

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19. ·ͱΊ
    • Secret Λ؆୯ʹѻ͑Δ k8sec ͱ͍͏πʔϧΛ

    ࡞Γ·ͨ͠
    
    • Go ͷ API client library Λ࢖ͬͯɺKubernetes Λ

    ௚઀ૢ࡞͢Δํ๏Λ঺հ͠·ͨ͠
    
    • ܅͚ͩͷ Kubernetes tool Λ࡞Ζ͏
    

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