UNOFFICIAL/EXPERIMENTAL. A Helm-fluent dev's cheat-sheet. cub installer uses declared, typed inputs and named bases - not free-form --set - so a little muscle-memory translation is needed. The good news: cub safely rejects Helm idioms (it never silently mishandles them); the gap this page fills is the migration guidance cub's error messages don't yet give you (measured in the Helm-fluent-migrant friction lane: every Helm idiom is rejected, but with a generic "unknown flag/input" and no hint toward the cub way).
The one big difference
- Helm: any
--set path=valueis accepted - including typos, which vanish silently. - cub: inputs are declared by the package. Run
cub installer doc <pkg>to see the exact inputs and bases. An unknown input or flag is a hard error (so the typo footgun Helm absorbs is caught at the tool). You customize via declared--inputs, a named--base,--set-image, or by editing the base (config-as-data).
The cheat-sheet
| In Helm you'd… | cub's error today | Do this in cub instead |
|---|---|---|
--set replicaCount=3 | unknown flag: --set | --input replicaCount=3 if it's a declared input (cub installer doc); otherwise choose/author a --base, or edit the base |
-f values.yaml / --values v.yaml | unknown shorthand flag: 'f' | cub has no values-file flag - pass declared values as --input k=v (repeatable), or author a base variant that bakes in your values |
--set image.tag=v2 | unknown flag: --set | --set-image <name>=<ref> (the base must declare an images: block) |
--set-string key=val | unknown flag: --set-string | --input key=val - inputs are typed by the package, so no --set-string needed |
--set-file key=cert.pem | unknown flag: --set-file | provide it as a declared input or a staged target fact (e.g. an existing Secret) |
--set nested.deep.path=x for a path the chart exposes but the package doesn't | unknown input "nested.deep.path" | that path isn't an exposed input - pick a --base that customizes it, or edit/author the base (the change becomes reviewable config-as-data) |
--set arr[0]=x (array index) | unknown input "arr[0]" | set the whole structured value via a declared input, or in the base |
helm install NAME chart (release name) | n/a - different model | cub renders into a --namespace; the "name" is the ConfigHub space / unit, not a Helm release |
What the managed setup guidance should say
| User tries | Better guidance |
|---|---|
--set replicaCount=2 | cub has no --set. Declared values use --input KEY=VALUE; run cub installer doc <pkg> to see the inputs. Values that are not declared belong in a base. |
--values values.yaml or -f values.yaml | cub has no values-file flag. Choose, edit, or author a base variant instead of passing a Helm values file at runtime. |
--set-string image.tag=7.4 | Use --set-image when the package declares images; otherwise make the image change in the base. |
--input replicaCount=2 but the input is not declared | The hard error is intentional. Confirm the input exists, or edit the base so the change is visible as config. |
| A base bakes a placeholder password | Treat it as a demo placeholder. The safer default is an existing-secret or reuse-existing-secret base; stage your own Secret before apply. |
Source: managed setup guidance.
Why cub works this way (the upside of the friction)
The declared-input model is what makes cub catch the typo footgun Helm silently absorbs - in the careless-dev fuzz, Helm swallowed ~66% of bad --set keys with no error; the same key as a cub --input is a hard unknown input. And because customization is a declared input, a named base, or a base edit, your change is reviewable config-as-data before it reaches a cluster, instead of a transient flag. The cost is this translation step - which is why this page (and, ideally, guidance baked into cub's own error messages) exists.
Quickest path
cub installer doc <pkg>- see the bases and the exact declared inputs.- Use
--base <name>to pick a variant,--input <name>=<value>for declared inputs, and--set-image <name>=<ref>for image overrides. - Anything else: edit or author a base (config-as-data) rather than spraying
--set.
→ see also: choosing-commands · cub-deployment-path · how-it-works