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Layered Architecture📜

It is essential to define each cluster layer as IaC/CaC and ensure automation is in place.

IaC/CaC Layers

VM Layer📜

Different deployment environments have different types of VM Images:

  • AWS has AMIs: Amazon Machine Images
  • Azure has Azure Managed VM Images
  • VMware has .vmdk Images

Packer is a tool that can create VM Image types that match the deployment environment automatically. Images in the VM layer are swappable yet consistent.

  • Use Packer with an ansible-remote provisioner to run Ansible Playbooks on a remote host during the Image Creation Process.

    • OpenSCAP: public ansible scripts to bring a VM to STIG compliance/C2S hardened.
    • Inspec: Tests & verifies infrastructure configuration.

VM Layer

Infrastructure Provisioning Layer📜

Terraform is a tool that automates the process of creating infrastructure. It uses VM Images made in the previous layer to provision VMs. Automated provisioning in the Infrastructure/VM layer is swappable yet consistent.

Terraform can be used to define Networking, Supporting Services, and VMs as Code and automate their provisioning.

It works for AWS, Azure, VMware and others.

VM Layer

Kubernetes Layer📜

Kubernetes distributions are like Linux distributions. Big Bang clusters come in flavors:

  • “Upstream Kubernetes” (kubeadm/archosaur/dod-tanzu)
  • Konvoy (Managed Kubernetes Cluster by D2IQ)
  • Rancher Kubernetes Engine
  • RedHat’s OpenShift Container Platform (BOY*)
  • (and more)

Kubernetes Layer

Cluster Services Layer📜

“Core” required services that you’d find in every Big Bang Cluster:

  • Flux
  • Istio
  • Open Policy Agent
  • Prometheus operator stack (Prometheus Grafana AlertManager)
  • Logging operator stack (Elastic FluentD Kibana)

Cluster Services Layer

Applications Layer📜

Users can add or remove applications in this layer based on the needs of a particular customer. The ArgoCD umbrella app deploys applications defined in a git repository to the cluster. You can share IaC for the apps you choose to run, then your CaC is different.

Applications Layer

GitOps Goals vs. Expectations📜

GitOps requires tight coupling of IaC (infrastructure as code) and CaC (configuration as code):

  • Users can quickly spin up a replacement cluster(<1 hour) if they destroy a pre-existing stateless cluster or dev cluster spun up using GitOps.

  • The fast redeployment time depends on prerequisites and configuration, which can’t always be automated/easily streamlined.

    • Deploying a similar cluster in the same AWS account can be figured out in one day.
    • Setting up a new cluster in a new AWS account, air-gapped environment, or restricted environment may require 1-3 weeks of preparation due to team handoffs for prerequisites and configuration.

Quiz Questions📜

What VM images does the VMware deployment environment have?

VMware has .vmdk Images

What is the tool that automates the process of creating infrastructure, that uses VM Images to provision VMs?

Terraform - it works for AWS, Azure, VMware and others

Can Kubernetes distributions be swapped out, similar Linux distributions?

Yes, Kubernetes distributions be swapped out, similar Linux distributions

Is Istio a “Core” required service that you’d find in every Big Bang Cluster?

Yes, Istio is one of the Core required services that can be found in every Bang Bang Cluster