Overview

• Developers, DevOps, App Operators are using different tools and methods to maintain infrastructure hosted in multiple platforms, deploying and maintaining applications into those infrastructures.
• Building culture isn’t just about communication and shared values — it’s also about tools.
• To deliver high-quality code fast and safely, we need a good developer platform.
• Let's build our common platforms like the cloud vendors build theirs - with a unified control plane.

What is Crossplane

Crossplane is a powerful tool for managing cloud-native infrastructure using a Kubernetes-style API. That one of UCP concept implementations.

Demo goals

• show crossplane capabilities, based on simple cloud deployment
• use crossplane to create an opinionated offering to order and deploy azure RG and SA
• create composition, to expose only a minimum amount of params

Why k8s for infrastructure provisioning

Kubernetes is powerful for two big reasons.

• The first is that Kubernetes allows you to treat multiple host servers - or "Nodes" - as a single computer. This means that Kubernetes will auto-schedule your containers to Nodes that have room for them.
• The second reason Kubernetes is powerful is because of its declarative API. "Declarative" means that you "declare" your desired state in a file, apply it to a cluster, and Kubernetes takes care of the rest, deploying your resources and "making it so." Rather than running imperative, "verb" commands like "run this container," Kubernetes' declarative model has you write down your "nouns."

The Kubernetes API Server is the central, most important part about a cluster because it’s the source of truth for both the desired and actual state of your cluster’s resources.

Crossplane vs Terraform

• Both allow engineers to model their infrastructure as declarative configuration
• Both support managing a myriad of diverse infrastructures using "provider" plugins
• Both are open-source tools with strong communities
• The key difference is that Crossplane is a control plane, where Terraform is a command-line tool - an interface to control planes.
• The Crossplane equivalent of a Terraform module is a Composite Resource
• Terraform sits in front of many APIs, but it does not offer its own.
• Teams automate by committing their Terraform configuration(s) to revision control (git) and executing Terraform as part of their CI/CD pipeline.
• Terraform is a command line tool - not a control plane.

Crossplane flow

High Level

Implementation

flowchart TB
    B[Install Kind-k8s]-->C[Install Crossplane Azure Provider]-->D[Create k8s Azure credentials]-->E[Install ProviderConfig]-->F[Create CompositeResource to Deploy RG and SA]-->G[Create Flux Infra repo]-->H[Create Flux Claim repo]-->I[Install and configure Flux]-->J[Claim for the resources]

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GitOps Flow

sequenceDiagram
autonumber
    Developer-->>Git: Create a repository from template and trigger CI
    Git-->>Flux: Register repo as a Source
    Flux-->>Flux: Create base Kustomization from the template folder
    Flux-->>Crossplane: Push base claims to the cluster
    Crossplane-->>Cloud Resources: Build base Infrastructure with Crossplane
    Cloud Resources-->>Developer: Consume cloud resources

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Low Level

flowchart LR
    subgraph Application
        DevTeam-->Claim
        Claim-->CompositeResource
    CompositeResource-->Package
    end
    subgraph Platform
    PlatformTeam-->Composition
    PlatformTeam-->CompositeResourcDefinition
    Composition-->CompositeResource
    CompositeResourcDefinition-->CompositeResource
    end

    subgraph Crossplane-k8s
    DevTeam-->Provider
    Provider-->ProviderConfig
    DevTeam-->Secret
    Secret-->ProviderConfig
    ProviderConfig-->ManagedResource
    Package-->ProviderConfig
    end

    subgraph CloudProvider
    ManagedResource-->CloudResource
    end

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Tools

• Flux as GitOps, but the same could be achieved with ArgoCD or Rancher Fleet
• Kind k8s cluster, AKS, EKS, or any managed service is fine too
• kubectl
• GitHub (Flux infra repository, claim repository)
• Crossplane and Crossplane CLI
• Azure/AWS credentials
• Azure/AWS provider