api: add Literal field to ValuesReference (CRD schema + docs)

Exposes the new `literal` field on `valuesFrom` entries, mirroring the
addition to `meta.ValuesReference` in fluxcd/pkg#1218. When set together
with `targetPath`, the referenced value is passed to Helm verbatim
(equivalent of `helm --set-literal`) instead of being parsed by
`strvals.ParseInto`, so file content containing commas, brackets, braces
or equal signs survives the round-trip intact.

This commit ships only the OpenAPI schema (so the field is validated by
the API server) and the user-facing documentation. The runtime support
lives in fluxcd/pkg/chartutil; once that PR merges and a `fluxcd/pkg`
release is cut, a follow-up will bump the dependency here so
helm-controller actually honours the field. Until then, setting
`literal: true` is accepted by the API but has no effect — the field is
forward-compatible.

Addresses #1317.

Signed-off-by: Gaal <g.gaal@salmon.group>

Author: Gaal

config/crd/bases/helm.toolkit.fluxcd.io_helmreleases.yaml

@@ -1080,6 +1080,17 @@ spec:
                       - Secret
                       - ConfigMap
                       type: string
+                    literal:
+                      description: |-
+                        Literal marks this ValuesReference as a literal value. When set in
+                        combination with TargetPath, the referenced value is merged at the target
+                        path without interpreting Helm's `--set` syntax (commas, brackets, dots,
+                        equal signs, etc.), mirroring the behavior of `helm --set-literal`. This
+                        is the only safe way to inject arbitrary file content (config files, JSON
+                        blobs, multi-line strings containing special characters) through
+                        `valuesFrom`. Has no effect when TargetPath is empty: in that mode the
+                        referenced value is always YAML-merged at the root.
+                      type: boolean
                     name:
                       description: |-
                         Name of the values referent. Should reside in the same namespace as the

docs/spec/v2/helmreleases.md

@@ -487,6 +487,13 @@ An item on the list offers the following subkeys:
   `true`, a not found error for the values reference is ignored, but any
   `valuesKey`, `targetPath` or transient error will still result in a
   reconciliation failure. Defaults to `false` when omitted.
+- `literal` (Optional): When set together with `targetPath`, the referenced
+  value is merged at the target path verbatim, without interpreting Helm's
+  `--set` syntax (commas, brackets, dots, equal signs, etc.). Mirrors the
+  behavior of `helm --set-literal`. Use this to inject arbitrary file content
+  (config files, JSON blobs, multi-line strings containing special characters)
+  through `valuesFrom`. Has no effect when `targetPath` is empty.
+  Defaults to `false` when omitted.
 
 ```yaml
 spec:
@@ -499,6 +506,11 @@ spec:
       valuesKey: crt
       targetPath: tls.crt
       optional: true
+    - kind: ConfigMap
+      name: app-config-source
+      valuesKey: application.yml
+      targetPath: 'externalConfig.application\.yml.content'
+      literal: true
 ```
 
 **Note:** The `targetPath` supports the same formatting as you would supply as
@@ -510,6 +522,11 @@ a list). You can read more about the available formats and limitations in the
 For JSON strings, the [limitations are the same as while using `helm`](https://github.com/helm/helm/issues/5618)
 and require you to escape the full JSON string (including `=`, `[`, `,`, `.`).
 
+To skip the `--set`-style parsing entirely and pass the value as a raw string
+(useful for full config files or any content containing `,`, `[`, `]`, `{`,
+`}`, `=`), set `literal: true` together with `targetPath`. This mirrors
+`helm --set-literal`.
+
 To make a HelmRelease react immediately to changes in the referenced Secret
 or ConfigMap see [this](#reacting-immediately-to-configuration-dependencies)
 section.