Building a Platform Engineering API Layer with KCP
5
kcp
platform
Baseline
Platform is automated and self service
We always have a bunch of consumers and service providers that get connected via an internal db plattform
graph TD
subgraph Consume
A
B
end
subgraph Provider
Cert
DB
end
IDP
A-->|discover available services|IDP
A-->|order db|IDP
IDP-->|Notify|DB
DB-->|fulfill|A
Why KubeAPI
We have it all: Groups, Versions, Optionally Namespaced, ...
It is extendable via CRDs
Challenges: CRDs are Cluster Scoped -> Everyone shares them across Namespaces
Idea: Everyone get's their own cluster
Problem: Spinning up clusters is slow and resource intensive
Idea: "Lightweight clusters" aka Hosted Control Plane
Problem: Now we have to share CRDs Across Clusters
WTF is KCP?
Idea: What if we had seperate control planes but with a shared datastore
Goal: Horitontally scalable control plane for extenable APIs
You don't need Kubernetes to run KCP (it's a standalone binary)
It does not spin up a real api server but a workspace wit a low memory footprint
It does not implement all of the container related stuff (Pod, Deployment, ...)
Access and setup
graph LR
User-->|Create APIServer Team A|KCP
KCP-->|Kubeconfig|User
subgraph KCP
APIA(Workspace Team A)
APIB(Workspace Team B)
Datastore
end
User-->|Kubectl get ns|APIA
APIA-->|Return NS for Workspace A|User
Internal Organization
Workspaces are organized in a tree
Possibility of nested fun: /clusters/root:org-a:team-a
Sub-Workspaces can't access ressources from the root workspace
KCP owns all Workspaces -> It can share stuff across clusters
To share: APIExport (Can Share multiple CRDs in one Package)
To use: APIBinding (Just reference the Exported API By Path to Workspace and name)
Order fulfillment
Classic Kubernetes: Controller -> But they are isolated, aren't they?
Virtual Workspace: Provite a computed view of parts of a workspace -> Basicly a URL that you provide to the controller that can be used to watch objects accross workspaces
Part of KCPs magic -> You don't create it, but it get's managed for each APIExport
Notes from the demo
Spin up locally is near instant
Switching to the namespace can be achived with a simple api command or
But why do we even need a universal API layer
Service Providers should not be responsible to make things discoverable, the plattform should
The internal pülatform can be bought, customized or diyed but the api layer does not change -> Interchangeable backend switching
Kubernetes is already widespread and makes it easy to use different projects
