Kf dependencies and architecture

Kf requires Kubernetes and several other OSS projects to run. Some of the dependencies are satisfied with Google-managed services—for example, Google Kubernetes Engine (GKE) provides Kubernetes.

Dependencies

• GKE
• Cloud Service Mesh
• Tekton Pipelines

Get CRD details

Kf supports the kubectl subcommand explain . It allows you to list the fields in Kf CRDs to understand how to create Kf objects via automation instead of manually via the CLI. This command is designed to be used with Config Management to automate creation and management of resources like Spaces across many clusters. You can use this against any of the component kinds below .

In this example, we examine the kind called space in the spaces CRD:

 kubectl  
explain  
space.spec 

The output looks similar to this:

 $  
kubectl  
explain  
space.spec
KIND:  
Space
VERSION:  
kf.dev/v1alpha1

RESOURCE:  
spec  
<Object>

DESCRIPTION:  
SpaceSpec  
contains  
the  
specification  
 for 
  
a  
space.

FIELDS:  
buildConfig  
<Object>  
BuildConfig  
contains  
config  
 for 
  
the  
build  
pipelines.  
networkConfig  
<Object>  
NetworkConfig  
contains  
settings  
 for 
  
the  
space ' 
s  
networking  
environment.  
runtimeConfig  
<Object>  
RuntimeConfig  
contains  
settings  
 for 
  
the  
app  
runtime  
environment. 

Kf components

Kf installs several of its own Kubernetes custom resources and controllers . The custom resources effectively serve as the Kf API and are used by the kf CLI to interact with the system. The controllers use Kf's CRDs to orchestrate the other components in the system.

You can view the CRDs installed and used by Kf by running the following command:

 kubectl  
api-resources  
--api-group = 
kf.dev 

The output of that command is as follows:

 NAME                      SHORTNAMES   APIGROUP   NAMESPACED   KIND
apps                                   kf.dev     true         App
builds                                 kf.dev     true         Build
clusterservicebrokers                  kf.dev     false        ClusterServiceBroker
routes                                 kf.dev     true         Route
servicebrokers                         kf.dev     true         ServiceBroker
serviceinstancebindings                kf.dev     true         ServiceInstanceBinding
serviceinstances                       kf.dev     true         ServiceInstance
spaces                                 kf.dev     false        Space 

Apps

Apps represent a twelve-factor application deployed to Kubernetes. They encompass source code, configuration, and the current state of the application. Apps are responsible for reconciling:

• Kf Builds
• Kf Routes
• Kubernetes Deployments
• Kubernetes Services
• Kubernetes ServiceAccounts
• Kubernetes Secrets

You can list Apps using Kf or kubectl :

 kf  
apps 
 kubectl  
get  
apps  
-n  
space-name 

Builds

Builds combine the source code and build configuration for Apps. They provision Tekton TaskRuns with the correct steps to actuate a Buildpack V2, Buildpack V3, or Dockerfile build.

You can list Builds using Kf or kubectl :

 kf  
builds 
 kubectl  
get  
builds  
-n  
space-name 

ClusterServiceBrokers

ClusterServiceBrokers hold the connection information necessary to extend Kf with a service broker. They are responsible for fetching the catalog of services the broker provides and displaying them in the output of kf marketplace .

You can list ClusterServiceBrokers using kubectl :

 kubectl  
get  
clusterservicebrokers 

Routes

Routes are a high level structure that contain HTTP routing rules. They are responsible for reconciling Istio VirtualServices.

You can list Routes using Kf or kubectl :

 kf  
routes 
 kubectl  
get  
routes  
-n  
space-name 

ServiceBrokers

ServiceBrokers hold the connection information necessary to extend Kf with a service broker. They are responsible for fetching the catalog of services the broker provides and displaying them in the output of kf marketplace .

You can list ServiceBrokers using kubectl :

 kubectl  
get  
servicebrokers  
-n  
space-name 

ServiceInstanceBinding

ServiceInstanceBindings hold the parameters to create a binding on a service broker and the credentials the broker returns for the binding. They are responsible for calling the bind API on the broker to bind the service.

You can list ServiceInstanceBindings using Kf or kubectl :

 kf  
bindings 
 kubectl  
get  
serviceinstancebindings  
-n  
space-name 

ServiceInstance

ServiceInstances hold the parameters to create a service on a service broker. They are responsible for calling the provision API on the broker to create the service.

You can list ServiceInstances using Kf or kubectl :

 kf  
services 
 kubectl  
get  
serviceinstances  
-n  
space-name 

Spaces

Spaces hold configuration information similar to Cloud Foundry organizations and spaces. They are responsible for:

• Creating the Kubernetes Namespace that other Kf resources are provisioned into.
• Creating Kubernetes NetworkPolicies to enforce network connection policies.
• Holding configuration and policy for Builds, Apps, and Routes.

You can list Spaces using Kf or kubectl :

 kf  
spaces 
 kubectl  
get  
spaces 

Third-party libraries

Third-party library source code and licenses can be found in the /third_party directory of any Kf container image.

You can also run kf third-party-licenses to view the third-party licenses for the version of the Kf CLI that you downloaded.