For_each attribute#

By default, a resource configures a single object. (Similarly, a module/package resource includes a child module's contents into the configuration one time.) However, sometimes you want to manage several similar resource (like a fixed pool of interfaces) without writing a separate resource for each one. Kform has two ways to do this: count and for_each.

If a resource or module/package block includes a for_each argument whose value is a map or a list, KForm will iterate over these elements in the map or list.

Usage#

for_each is an attribute defined by the KForm language. You can use the for_each attribute in all block-types except the input block-type

The for_each attribute accepts a map or list, and creates that many instances of the resource or module/package. Each instance has a distinct resource associated with it, and each is separately created, updated, or deleted when the configuration is applied.

apiVersion: v1
kind: ConfigMap
metadata:
  name: '["example", each.index].concat("-")'
  namespace: example-system
  annotations:
    kform.dev/for_each: input.context[0].data.entries
data:
  image: each.key

The for_each variable#

In resources where the for_each attribute is specified, KForm automatically defines an additional each variable, enabling dynamic configuration adjustments for each instance. This each object facilitates modification of individual configurations within the resource. It comprises of two attribute:

• each.key: The map key (or list index) corresponding to this instance.
• each.value: The map or list value corresponding to this instance.

Using expressions in for_each#

Map or list expressions can be used in the for_each attribute. These expressions are included in the dependency calculation such that the data of the expression is available when rendering the resource using the for_each expression.

Referring to for_each resources.#

A resource is always referred to as <RESOURCE-TYPE>.<RESOURCE-ID>[INDEX]. Normally Index is 0 but resources that use for_each could refer to an index different then 0.