container.training/slides/k8s/whatsnext.md

Next steps

Alright, how do I get started and containerize my apps?

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Suggested containerization checklist:

.checklist[

• write a Dockerfile for one service in one app
• write Dockerfiles for the other (buildable) services
• write a Compose file for that whole app
• make sure that devs are empowered to run the app in containers
• set up automated builds of container images from the code repo
• set up a CI pipeline using these container images
• set up a CD pipeline (for staging/QA) using these images ]

And then it is time to look at orchestration!

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Options for our first production cluster

• Get a managed cluster from a major cloud provider (AKS, EKS, GKE...)

  (price: $, difficulty: medium)

• Hire someone to deploy it for us

  (price: $$, difficulty: easy)

• Do it ourselves

  (price: -$$, difficulty: hard)

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One big cluster vs. multiple small ones

• Yes, it is possible to have prod+dev in a single cluster

  (and implement good isolation and security with RBAC, network policies...)

• But it is not a good idea to do that for our first deployment

• Start with a production cluster + at least a test cluster

• Implement and check RBAC and isolation on the test cluster

  (e.g. deploy multiple test versions side-by-side)

• Make sure that all our devs have usable dev clusters

  (whether it's a local minikube or a full-blown multi-node cluster)

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Stateful services (databases etc.)

• As a first step, it is wiser to keep stateful services outside of the cluster

• Exposing them to pods can be done with multiple solutions:

  • ExternalName services
    (redis.blue.svc.cluster.local will be a CNAME record)

  • ClusterIP services with explicit Endpoints
    (instead of letting Kubernetes generate the endpoints from a selector)

  • Ambassador services
    (application-level proxies that can provide credentials injection and more)

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Managing stack deployments

• The best deployment tool will vary, depending on:

  • the size and complexity of your stack(s)
  • how often you change it (i.e. add/remove components)
  • the size and skills of your team

• A few examples:

  • shell scripts invoking kubectl
  • YAML resources descriptions committed to a repo
  • Helm (~package manager)
  • Spinnaker (Netflix' CD platform)
  • Brigade (event-driven scripting; no YAML)

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Cluster federation

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Sorry Star Trek fans, this is not the federation you're looking for!

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(If I add "Your cluster is in another federation" I might get a 3rd fandom wincing!)

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Cluster federation

• Kubernetes master operation relies on etcd

• etcd uses the Raft protocol

• Raft recommends low latency between nodes

• What if our cluster spreads to multiple regions?

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• Break it down in local clusters

• Regroup them in a cluster federation

• Synchronize resources across clusters

• Discover resources across clusters

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Developer experience

We've put this last, but it's pretty important!

• How do you on-board a new developer?

• What do they need to install to get a dev stack?

• How does a code change make it from dev to prod?

• How does someone add a component to a stack?