Skip to content

Custom Resources

CAPTF adds seven kinds to the infrastructure.cluster.x-k8s.io/v1alpha1 API group. Three run a Terraform or OpenTofu module, one per role of the module contract; three are templates Cluster API clones them from; and one holds the cloud credentials the others use. Each has its own page here: what it is, a minimal and a full YAML example, and every field of its spec and status, with its type, default, validation and what it does.

The kinds

Kind Scope Runs Referenced by
TerraformCluster Namespaced The cluster role Cluster.spec.infrastructureRef
TerraformMachine Namespaced The machine role Machine.spec.infrastructureRef
TerraformMachinePool Namespaced The machinepool role MachinePool.spec.template.spec.infrastructureRef
TerraformClusterTemplate Namespaced Nothing; cloned into a TerraformCluster ClusterClass.spec.infrastructure.templateRef
TerraformMachineTemplate Namespaced Nothing; cloned into each TerraformMachine MachineDeployment and MachineSet spec.template.spec.infrastructureRef, the control plane’s machine template, and ClusterClass machine infrastructure templateRefs
TerraformMachinePoolTemplate Namespaced Nothing; cloned into a TerraformMachinePool ClusterClass.spec.workers.machinePools[].infrastructure.templateRef
TerraformClusterIdentity Cluster Nothing; its Secret feeds the others’ Jobs The others’ spec.identityRef 
flowchart LR
    Cluster --> TC[TerraformCluster]
    Machine --> TM[TerraformMachine]
    MachinePool --> TMP[TerraformMachinePool]
    TCT[TerraformClusterTemplate] -. cloned into .-> TC
    TMT[TerraformMachineTemplate] -. cloned into .-> TM
    TMPT[TerraformMachinePoolTemplate] -. cloned into .-> TMP
    TC --> ID[TerraformClusterIdentity]
    TM --> ID
    TMP --> ID

Every kind is in the cluster-api category, so kubectl get cluster-api -A lists them with the Cluster API objects. None has a short name. For how the kinds relate to Cluster API’s objects in practice, see The Kinds.

Reading these pages

  • Field paths are written in full from the object’s root, such as spec.drift.intervalSeconds. An item of a list is written []: spec.variablesFrom[].secretRef.name.
  • Each field’s description says what it does, then whether it is Required, its Default and where that default comes from (the admission webhook, the controller, or a manager flag), whether it is Immutable, and its Allowed values or Range.
  • Validation sections list what the admission webhooks reject. The CRDs themselves declare no defaults; every default named here is applied by CAPTF.
  • Shared fields. TerraformCluster, TerraformMachine and TerraformMachinePool share their module source, identity, Job settings, variables and most of their status. Each kind’s page lists those fields and links to Common Fields, which covers them in full.

These pages are kept in step with the provider’s API: a check fails when the CRDs gain or lose a field a page does not name (see Writing Documentation).