hydra local template¶

Render Helm templates for one or more applications and output the resulting Kubernetes manifests.

CLI help recording¶

Synopsis¶

hydra local template <appId> [appId...] [flags]

Description¶

Processes the Helm charts for the specified applications through the Hydra rendering pipeline and outputs the resulting Kubernetes YAML manifests. Runs entirely locally — no cluster connection required.

This is the go-to command for inspecting what Hydra would produce before deploying. Conceptually equivalent to helm template, but uses Hydra's embedded Helm engine with its context hierarchy, values composition, and dependency resolution applied.

Hydra may cache Helm render results under each root app directory in GitOps: .hydra/cache/helm/cache.yaml and templates.yaml for the root app chart, and cache-<childApp>.yaml / templates-<childApp>.yaml for child apps. Cached output is reused only when the serialized render inputs match. Use --no-cache or set HYDRA_NO_CACHE to force a full render and skip these caches.

Output is always normalized to sorted multi-document YAML from Hydra’s entity pipeline (no Helm # Source: file headers). hydra local template does not append the synthetic kubernetes-defaults-* bundle (v1/Namespace, namespaced ServiceAccount named default, ConfigMap/kube-root-ca.crt) that hydra gitops template and RenderCluster add for exclusive namespaces; those placeholders exist only on cluster render paths.

Optional global.hydra.templatePatches in the app’s values (or Hydra ConfigMap data.hydra) runs before scope validation and again as a final step on the printed manifest set (per-app render and, when present, the clone appendix after ---). Rules can also live only in another app’s chart (for example a cluster-wide ConfigMap under the Argo CD app): hydra local template still merges those fragments by combining the full-cluster scope-catalog render (from the Git checkout) with the selected app’s partition when collecting patch rules (see templatePatches in Values). The early pass can fix invalid raw chart output such as metadata.namespace on a cluster-scoped resource; the final pass must not change resource identity (apiVersion, kind, metadata.name, metadata.namespace) and must not mutate Hydra configuration ConfigMaps (hydra-gitops.org/hydra-config: "true" with data.hydra).

When --include or --exclude is set, template patches run first, then only resources matching the combined CEL predicates are printed (same CEL model as hydra local find for the filter step).

To print only the sorted, deduplicated Hydra resource ids for the same render (for scripting or quick inventory), use hydra local list.

When To Use It¶

Use hydra local template when you want to answer local rendering questions without touching a cluster:

What YAML will Hydra generate for this app?
Did my values or chart change alter the rendered output?
Can another tool validate the rendered manifests?

When you need live-cluster comparison instead of local rendering, continue with hydra gitops diff.

When you want rendered YAML that still reflects this cluster’s preferred API versions, includes synthetic kubernetes-defaults objects for exclusive namespaces, and applies templatePatches with the same namespace-owner attribution rules used on other cluster commands, use hydra gitops template. That command is read-only but requires kube API access for discovery; see its manual page for a feature comparison with hydra local template.

Arguments¶

Argument	Description
`appId`	One or more App IDs (supports wildcards)

Flags¶

Flag	Short	Description
`--hydra-context`		Path to the Hydra context directory (or set `HYDRA_CONTEXT` env var)
`--color`	`-c`	Force colored output
`--no-color`		Disable colored output
`--color-mode`		Color mode: `auto`, `always`, or `never`
`--helm-network-mode`		Helm network mode: `online`, `local`, `offline`, or `error`
`--no-cache`		Disable persistent Helm template cache and in-process Helm-related caches for this run
`--exclude-app`		Glob pattern to exclude applications (repeatable)
`--include`	`-i`	CEL expression to filter resources
`--exclude`	`-e`	CEL expression to exclude resources
`--bootstrap`		Include `global.hydra.clones` rules tagged `bootstrap` and append their YAML after each app’s render; fails if the flag is unnecessary (debugging aid)

Examples¶

# Render templates for a single app
hydra local template prod.infra.cert-manager

# Render all child apps under a root app
hydra local template prod.infra.*

# Render only Deployments
hydra local template prod.apps.my-service --include 'kind == "Deployment"'

# Pipe to kubectl for validation
hydra local template prod.infra.cert-manager | kubectl apply --dry-run=server -f -

# Compare rendered output between environments
diff <(hydra local template staging.infra.cert-manager) <(hydra local template prod.infra.cert-manager)

# Pipe to kubeconform or similar tools
hydra local template prod.infra.* | kubeconform -strict

# Render offline (no chart downloads)
hydra local template prod.infra.* --helm-network-mode offline

Example: Argo CD server-side apply on CRDs¶

Prefer a single Hydra ConfigMap in the Argo CD app chart (hydra-gitops.org/hydra-config: "true", data.hydra.templatePatches) so every cluster app inherits the same rule without repeating YAML in each chart’s values. Alternatively, declare the rule under global.hydra.templatePatches in a given app’s Helm values. Use a CEL predicate on CustomResourceDefinition and a yq expression that sets metadata.annotations["argocd.argoproj.io/sync-options"]. Keep the expression idempotent if you merge with existing options (comma-separated list). Exact yq depends on your charts; validate with hydra local template before committing.

global:
  hydra:
    templatePatches:
      crdArgoServerSideApply:
        predicate: 'gvk == "apiextensions.k8s.io/v1/CustomResourceDefinition"'
        patches:
          - yq: '.metadata.annotations."argocd.argoproj.io/sync-options" = "ServerSideApply=true"'

Tutorials¶

Adding Manifests to the Helm Charts — uses hydra local template to render the first app manifests and compare Hydra output with Helm