Helm chart: Support custom key name used for secret key lookup for APOLLO_KEY

.changesets/feat_helm_existingsecretkeyrefkey.md

@@ -0,0 +1,9 @@
+### Provide support to control of the key name used to retrieve the secret used for APOLLO_KEY ([Issue #5661](https://github.com/apollographql/router/issues/5661))
+
+The Router Helm chart currently is hardcoded to use managedFederationApiKey as the key name to use to retrieve the value 
+out of the referenced secretkey.   Some kubernetes customers require the use of a secretStore / externalSecret,
+and may be required to use a specific key name when obtaining secrets from these sources.
+
+This change provides the user the ability to control the name of the key to use in retrieving that value.
+
+By [Jon Christiansen](https://github.com/theJC) in https://github.com/apollographql/router/pull/5662

helm/chart/router/templates/deployment.yaml

@@ -76,7 +76,7 @@ spec:
               valueFrom:
                 secretKeyRef:
                   name: {{ template "router.managedFederation.apiSecretName" . }}
-                  key: managedFederationApiKey
+                  key: {{ (.Values.managedFederation.existingSecretKeyRefKey | default "managedFederationApiKey") }}
                   optional: true
             {{- end }}
             {{- if not (empty .Values.managedFederation.graphRef) }}

helm/chart/router/templates/secret.yaml

@@ -9,5 +9,5 @@ metadata:
     {{- include "apollographql.templatizeExtraLabels" . | trim | nindent 4 }}
     {{- end }}
 data:
-  managedFederationApiKey: {{ default "MISSING" .Values.managedFederation.apiKey | b64enc | quote }}
+  {{ (.Values.managedFederation.existingSecretKeyRefKey | default "managedFederationApiKey") }}: {{ default "MISSING" .Values.managedFederation.apiKey | b64enc | quote }}
 {{- end }}

helm/chart/router/values.yaml

@@ -21,6 +21,9 @@ managedFederation:
   # -- If using managed federation, use existing Secret which stores the graph API key instead of creating a new one.
   # If set along `managedFederation.apiKey`, a secret with the graph API key will be created using this parameter as name
   existingSecret:
+  # -- If using managed federation, the name of the key within the existing Secret which stores the graph API key.
+  # If set along `managedFederation.apiKey`, a secret with the graph API key will be created using this parameter as key, defaults to using a key of `managedFederationApiKey`
+  existingSecretKeyRefKey:
   # -- If using managed federation, the variant of which graph to use
   graphRef: ""