Fix: resolve null error for standalone mode in cluster chart

[mschiller-artisight]

Fix: resolve null error for standalone mode in cluster chart

/charts/cluster/templates/_external_clusters.tpl

{{- define "cluster.externalClusters" -}}
{{- if eq .Values.mode "standalone" }}
externalClusters: []
{{- else if eq .Values.mode "recovery" }}
externalClusters:
  {{- if eq .Values.recovery.method "pg_basebackup" }}
  - name: pgBaseBackupSource
     {{- include "cluster.externalSourceCluster" .Values.recovery.pgBaseBackup.source | nindent 4 }}
  {{- else if eq .Values.recovery.method "import" }}
  - name: importSource
     {{- include "cluster.externalSourceCluster" .Values.recovery.import.source | nindent 4 }}
  {{- else if eq .Values.recovery.method "object_store" }}
  - name: objectStoreRecoveryCluster
    barmanObjectStore:
      serverName: {{ .Values.recovery.clusterName }}
      {{- $d := dict "chartFullname" (include "cluster.fullname" .) "scope" .Values.recovery "secretPrefix" "recovery" -}}
      {{- include "cluster.barmanObjectStoreConfig" $d | nindent 4 }}
  {{- end }}
{{- else if eq .Values.mode "replica" }}
externalClusters:
  - name: originCluster
  {{- if not (empty .Values.replica.origin.objectStore.provider) }}
    barmanObjectStore:
      serverName: {{ .Values.replica.origin.objectStore.clusterName }}
      {{- $d := dict "chartFullname" (include "cluster.fullname" .) "scope" .Values.replica.origin.objectStore "secretPrefix" "origin" -}}
      {{- include "cluster.barmanObjectStoreConfig" $d | nindent 4 -}}
  {{- end }}
  {{- if not (empty .Values.replica.origin.pg_basebackup.host) }}
    {{- include "cluster.externalSourceCluster" .Values.replica.origin.pg_basebackup | nindent 4 }}
  {{- end }}
{{- else }}
  {{ fail "Invalid cluster mode!" }}
{{- end }}
{{ end }}

This fix resolves a null error that occurred when installing the cluster chart in standalone mode. The issue was caused by the externalClusters key being defined outside of the conditional blocks in the _external_clusters.tpl template, which resulted in an improperly structured YAML output. The fix moves the externalClusters definition inside each conditional block and explicitly initializes it as an empty array ([]) for standalone mode, ensuring proper YAML structure and preventing null reference errors during chart installation.

[dosubot]

Hi @mschiller-artisight! I'm Dosu and I’m helping the charts team.

The null error happens because the CloudNativePG CRD requires spec.externalClusters to always be an array, but the Helm chart was rendering it as null in standalone mode, which fails validation and breaks installation. The fix you described—moving the externalClusters definition inside each conditional block and explicitly setting it to an empty array (externalClusters: []) for standalone mode—ensures the manifest is always valid YAML and satisfies the CRD schema. This approach is necessary because standalone clusters (using initdb bootstrap) do not need any external sources, so externalClusters should be empty, not omitted or null. There’s no Helm --set workaround for this; the template must be patched as you did. This matches both the chart’s design and the documented requirements for cluster bootstrapping modes source, docs.

To reply, just mention @dosu.

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