vs Flux Operator ResourceSet
JaaS and the Flux Operator
’s ResourceSet solve
different halves of the same delivery problem, so reach for them together rather
than choosing between them. JaaS renders content: it evaluates a JsonnetSnippet
and publishes the resulting JSON as a Flux ExternalArtifact. A ResourceSet
fans out instances: it takes a set of inputs and templates one copy of a set of
Kubernetes or Flux objects per input. Neither does the other’s job — a
ResourceSet has no Jsonnet evaluator, and JaaS has no input matrix — so the two
slot together cleanly.
What each one produces
JaaS turns Jsonnet into bytes. You hand the operator a JsonnetSnippet (inline
spec.files or a spec.sourceRef to a Flux source), it runs go-jsonnet, and it
writes the evaluated JSON to a content-addressed ExternalArtifact that any Flux
consumer can fetch and pin. The input is a Jsonnet program plus its top-level
arguments and external variables; the output is one rendered document.
ResourceSet turns a list of inputs into a fleet of objects. You give it
.spec.inputs (static value sets) and .spec.inputsFrom (references to
ResourceSetInputProvider objects that export inputs from Git branches, pull
requests, OCI tags, or a static list), combine them with .spec.inputStrategy
(Flatten or Permute), and template the result into .spec.resources (or
.spec.resourcesTemplate) using Go templates with << inputs.x >> delimiters.
The output is N rendered objects, one per resolved input.
Where each one fits
| You want to… | Reach for |
|---|---|
| Evaluate Jsonnet (grafonnet dashboards, manifest libraries) into JSON | JaaS JsonnetSnippet |
| Re-render automatically when a Flux source republishes | JaaS spec.sourceRef |
| Create one copy of a resource per tenant, cluster, or environment | ResourceSet |
| Drive that fan-out from Git branches, PRs, or OCI tags | ResourceSetInputProvider |
| Gate when inputs refresh to a time window | ResourceSetInputProvider .spec.schedule |
A ResourceSet can template a JsonnetSnippet as one of its .spec.resources,
which is exactly where they compose: the ResourceSet produces one snippet per
input, and JaaS renders each one. You get per-tenant or per-cluster Jsonnet output
without authoring a snippet by hand for every instance.
They compose
The practical pattern — a ResourceSet that templates a JsonnetSnippet per
input so JaaS renders per-cluster or per-tenant content — has a complete, working
example on the Flux Operator integration
page.
Neither tool replaces the other: drop the Flux Operator if you only ever render one document per snippet, and drop JaaS if your objects need no Jsonnet evaluation. When both are true — many instances, each rendered from Jsonnet — run them side by side.