Templating

Fast Templates

For simple template cases we provide a fast templating engine. With this engine, you can use Go templates syntax to reference Tenant and Namespace fields. There are no operators or anything else supported.

Available fields are:

• {{tenant.name}}: The Name of the Tenant
• {{namespace}}: The Name of the Tenant

Sprout Templating

Our template library is mainly based on the upstream implementation from Sprout. You can find the all available functions here:

• https://docs.atom.codes/sprout/registries/list-of-all-registries

We have removed certain functions which could exploit runtime information. Therefor the following functions are not available:

• env
• expandEnv

Data

You can provide structured data for each Tenant which can be used in templating:

apiVersion: capsule.clastix.io/v1beta2
kind: Tenant
metadata:
  name: solar
spec:
  data:
    bool: true
    foo: bar
    list:
    - a
    - b
    number: 123
    obj:
      nested: value

Custom Functions

Custom Functions we provide in our template package.

deterministicUUID

deterministicUUID generates a deterministic, RFC-4122–compliant UUID (version 5 + RFC4122 variant) from a set of input strings. It is designed for use in templates where you need stable, repeatable IDs derived from meaningful inputs (e.g. cluster name, tenant, role name), instead of random UUIDs.

This is especially useful for:

• Crossplane / IaC resources that must not change IDs across reconciles

The function takes any number of strings and turns them into a UUID in a fully deterministic way.

What that means in practice:

• If you call it twice with the same values, you get the same UUID
• If any input changes, the UUID changes too
• There is no randomness involved
• The output is always a valid UUID

So from the outside, it behaves just like a normal UUID — just deterministic.

deterministicUUID(parts ...string) string

Example usage:

{{ deterministicUUID "cluster-a" "app-123" "tenant-x" "some-role" }}