How to become a gophernetes

The Go community well knows what a Cryptogopher is! Today is the way where you will learn about how a Gophernetes looks like! Kubernetes is all about extendibility. That’s why every cloud provider is able to plug their network implementation, storage layer or compute platform to it. But in order to do so, you have to write code to glue your platform or external project with Kubernetes itself. Gophers are in a unique position when it comes to writing code for Kubernetes because even if there is an API that gives you the opportunity to write integration in any language, it is written in Go, and that’s a huge benefit. This talk is for Gopher that want to become Kubernetes developers also called gopherneters. I participated in various efforts around integration at storage layers, with the container storage interface, or container runtime interface and recently with cluster-api, the abstract that drives the Kubernetes provisioning in a declarative way. It means that I wrote a good amount of Custom Resource Definitions (CRDs), Shared Informers and so on. It is a jungle and I will share what I learned in terms of best practices, testing to write solid Kubernetes integrations.

Transcript

1. How to Become a Gophernetes
   Gianluca Arbezzano / @gianarb
   

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2. K8s is Hard
   and there’s nothing wrong with that
   

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3. What is a Gophernetes?
   What does it look like?
   

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4. What is a Gophernetes?
   • Develop applications running in Kubernetes
   • Develop Kubernetes
   • Develop on the Kubernetes Foundation
   

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5. What does it look like?
   

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6. Where are they?
   • Kubernetes Slack
   • GitHub around the kubernetes or kubernetes-sigs organization
   

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7. https://kubernetes.io/docs/concepts/architecture/cloud-controller/
   

   

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8. https://kubernetes.io/blog/2018/07/18/11-ways-not-to-get-hacked/
   

   

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9. https://github.com/kubernetes/website/blob/master/content/en/blog/_posts/2017-11-00-Containerd-Container-Runtime-Options-Kubernetes.md
   

   

   

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10. Extensibility is the key
    Kubernetes is a blob of APIs
    ● API Server
    ● CRI (Container Runtime
    Interface: docker, containerd)
    ● CNI (Container Networking
    Interface: calico, flannel)
    ● CSI (Container Storage
    Interface: aws-ebs, packet-csi)
    This is how it abstracts your
    workflow from your infrastructure
    API Server
    kubelet
    CSI CNI CRI
    

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11. About Me

    Gianluca Arbezzano
    • Gophernetes at Packet.com
    • www.gianarb.it / @gianarb
    What I like:
    • I make dirty hacks that look awesome
    • I grow my vegetables
    • Travel for fun and work
    

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12. Workflow?
    Workflow is the reason behind why we have Kubernetes. It is the end goal for any
    good Gophernetes.
    Being able to leverage kubernetes extendibility to implement the best workflow you
    can even image.
    Examples of workflows:
    ● Troubleshooting and debugging
    ● Observability (data pipeline for logs, metrics, traces)
    ● Delivery (canary release, blue green deployment, progressive delivery, your own
    one)
    

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13. Workflow
    The Gophernetes is the limitation.
    It means that in theory with good code you can whatever you image
    

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14. Extensibility is the key
    

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15. • Event system
    • Share informers
    • Custom Resource Definitions
    • Kubecutl plugin
    • ClusterAPI (Packet implementation is under active development! Watch
    out!)
    How do you extend Kubernetes in practice?
    

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16. Gophernetes toolchain
    • kubernetes/client-go
    • kubernetes/cli-runtime
    • kubernetes-sigs/kind
    

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17. Kubectl Plugin
    $ cat > /usr/local/bin/kubectl-hello
    #!/bin/bash
    echo "this is a simple kubectl plugin. But gophernetes can do better, because this is bash..."
    ^C
    $ chmod +x /usr/local/bin/kubectl-hello
    $ kubectl hello
    this is a simple kubectl plugin. But gophernetes can do better, because this is bash...
    

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18. Shared
    Informer
    https://gianarb.it/blog/kubernetes-shared-informer
    

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19. The UX is crucial.
    Keep it as close as
    possible with the
    Kubernetes one...
    

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20. Authentication
    

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21. Flags
    Companies and teams invests a lot of time learning kubernetes and its cli.

    Tools developed to Gophernetes has to keep the same flavour.
    It should be the same as running a bike, does not matter which one you own, it
    always looks familiar.
    

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22. Flags: github.com/kubernetes/cli-runtime
    This library is a shared dependency for clients to work with Kubernetes API
    infrastructure which allows to maintain kubectl compatible behavior. Its first
    consumer is k8s.io/kubectl.
    

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23. Flags: kubectl-profefe uses it as well
    My expectations as a kubernetes user for examples are (at least):
    ● When I have to do filtering
    ○ Label Selection: -l app=dev -l runtime=1.14 (--selector)
    ○ Namespace selection: -n namespace (--namespace)
    ○ -a (--all-namespaces)
    ● When it comes to authentication
    ○ --kubeconfig
    ● Output
    ○ -o yaml | json (--output)
    

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25. • kubernetes-sigs/krew-index
    • kubernetes-sigs/krew
    Krew makes plugins easy to install and discover
    $ kubectl krew install profefe

    $ kubectl krew install tree

    $ kubectl krew install ctx

    

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26. The CLI runtime contains utils to
    print tables from cli, but I didn’t use
    it yet!
    

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27. Production is a dangerous place.

    Usually hard to work with (reasonable)…

    

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28. Kubernetes gives you for free a couple of things:
    • As we saw, a consistent API and a solid ecosystem to interact with it
    • Authentication (that you can plug with your identity management)
    • Authorization with RBAC
    • Audit logs
    Why?
    

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29. • Kubernetes Assemble
    • https://get.oreilly.com/ind_extending-kubernetes.html
    • Programming Kubernetes: Developing Cloud-Native Applications
    • Krew kubectl plugin index
    • jtblin/kube2iam
    • https://gianarb.it
    THANKS
    LINKS
    

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30. Thanks
    @gianarb / gianarb.it
    

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