Allow overriding external database name in Nominatim chart

[frascu]

This PR allows specifying a custom name for an external database in the Nominatim Helm chart.

Main changes:

1. _helpers.tpl
   • Updated the nominatim.databaseName function to return:
   • "nominatim" if internal PostgreSQL is enabled (.Values.postgresql.enabled = true)
   • The value of .Values.externalDatabase.databaseName if using an external database (.Values.postgresql.enabled = false)
2. values.yaml
   • Added externalDatabase.databaseName parameter to configure the external database name:

      ## @param externalDatabase.databaseName External Database name
      ##
      databaseName: nominatim

Benefits:

• Enables customizing the name of an external database without changing other chart configurations.
• Improves flexibility for deployments using pre-existing external databases.

[robjuz]

@frascu Thax for the PR

Are you sure this will work? Nominatim was always expecting that the database is nominatim

[frascu]

It works because the connection is defined via the NOMINATIM_DATABASE_DSN environment variable, which is generated as follows:

{{- define "nominatim.databaseDSN" -}}
pgsql:dbname={{ include "nominatim.databaseName" . }};host={{ include "nominatim.databaseHost" . }};port={{ include "nominatim.databasePort" . }};user={{ include "nominatim.databaseUser" . }};password={{ include "nominatim.databasePassword" . }}
{{- end }}

As you can see, the database name is included in the DSN and therefore correctly used by Nominatim.

I tested this setup on the same Kubernetes cluster with the same PostgreSQL instance, using multiple databases with different names, and it worked as expected.