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Input KForm Resource#

Input KForm resources let you customize aspects of a Kform module/package without altering the KForm module/package source code/configuration. This functionality allows you to share KForm modules/packages across different Kform configurations, making your KForm module/package composable and reusable.

When you declare an input KRM resource in the root module/package of your configuration, you can set their values using CLI options. When you declare input KRM resource in child modules/packages, the calling module/package should pass values in the module/package KRM resource.

Kform's input resources can be compared to function arguments in traditional programming.

Input#

A KRM resource is defined as an input blockType by setting the annotation kform.dev/block-type = input. An Input resource is uniquely identified by the combination of the blockType and its resourceID. The resourceID is defined by the kform.dev/resource-id annotation or the metadata.name if the kform.dev/resource-id annotation is not present. A resourceID is mandatory and must be unique accross input resources in the same module/package.

An input resource example is shown below

apiVersion: v1
kind: ConfigMap
metadata:
  name: example-app
  namespace: example-system
  annotations:
    kform.dev/block-type: input
    kform.dev/resource-id: context 
    kform.dev/default: "true"
data:
  image: a.b

Attributes#

The following optional attributes can be defined for input resources through annotations:

  • default - A default value which then makes the input KRM resource optional.
  • description - This specifies the input KRM resource documentation.
  • sensitive - Limits UI output when the variable is used in configuration.

Default attribute#

When an input resource is declared as default, the input KRM resource will be used if no input KRM resource with that resourceID is present when calling the module/package. A default input resource cannot have references/expressions with other resources.

Description attribute#

description attribute

Sensitive attribute#

sensitive attribute

Using Input Resources#

Values from input resources can be accessed through expressions using the following syntax: - input., where matches the resourceID that is either defined by the kform.dev/resource-id annotation or the metadata.name if the kform.dev/resource-id annotation is not present.

In the example below, the input resource e.g. input.context can only be accessed in expressions within the module/package where it was declared. Also note that KForm stores the resources as a list, which means expressions must use input.context[0] to access the values of the first entry in the list.

apiVersion: v1
kind: ConfigMap
metadata:
  name: example-app
  namespace: example-system
  annotations:
    kform.dev/block-type: input
    kform.dev/resource-id: context 
    kform.dev/default: "true"
data:
  image: a.b

When using input resources, they must be defined within the module/package, if not the Kform parser will throw an error

Customizing input resources within a module/package#

Input Resources that are declared in the root module/package of your configuration, can be customized through:

  • cli options: -i (input file or input dir), which can source from a file or directory
  • kform library using the inputData variable

The input resources, specified as dynamic input can omit the block-type annotation since kform knows these that dynamic input data are to be used as input block-types.

apiVersion: v1
kind: ConfigMap
metadata:
  name: my-app
  namespace: my-system
  annotations:
    kform.dev/resource-id: context 
data:
  image: my-image

command line#

To customize the input resources used in a module/package, an input file or directory can be specified in the command line. 

kform apply -i <input file or input dir>

kform library#

When using Kform as a library, you can specify the input resources in the input data.

kfrunner := runner.NewKformRunner(&runner.Config{
  PackageName:  cr.Spec.PackageID.Package,
  InputData:    inputData,
  ResourceData: resourceData,
  OutputData:   outputData,
})

Declaring input resources#

When using dynamic input resource, KForm will validate if the corresponding input is defined within the package, if not a WARNING message will be shown since this data will not be used.

e.g. if you define within your module/package the following input resource

apiVersion: v1
kind: ConfigMap
metadata:
  name: example-app
  namespace: example-system
  annotations:
    kform.dev/block-type: input
    kform.dev/resource-id: context 
    kform.dev/default: "true"
data:
  image: a.b

The following dynamic input resource is specified with a resourceID that is unknown (e.g. ctx in this case), KForm will throw a warning to indicate the potential misconfiguration.

apiVersion: v1
kind: ConfigMap
metadata:
  name: my-app
  namespace: my-system
  annotations:
    kform.dev/resource-id: ctx
data:
  image: my-image

Input Resource Preference#

Kform will prioritize dynamic input resources over the once specified in the module/package itself.