How to configure Harbor with external database and sslmode

Question

I have a postgresql database where ssl is required

resource "google_sql_database_instance" "instance" {
  provider = google-beta

  name                = "harbor-postgre"
  region              = "europe-west1"
  database_version    = "POSTGRES_13"
  deletion_protection = false
  depends_on          = [google_service_networking_connection.harbor_postgresql_vpc_connection]

  settings {
    tier            = "db-g1-small"
    disk_size       = "100"
    disk_autoresize = true
    disk_type       = "PD_SSD"
    #availability_type = "REGIONAL"
    ip_configuration {
      ipv4_enabled    = false
      private_network = google_compute_network.tools_europe_west1_vpc.id
      require_ssl     = true 
    }
  }
}

I want to deploy harbor by using the helmchart. In the values.yaml set set the following

database:
  # if external database is used, set "type" to "external"
  # and fill the connection informations in "external" section
  type: external
  external:
    host: "xxx.xx.xxx.x"
    port: "xxxx"
    username: "postgres"
    password: "xxx"
    coreDatabase: "registry"
    notaryServerDatabase: "notary_server"
    notarySignerDatabase: "notary_signer"
    # "disable" - No SSL
    # "require" - Always SSL (skip verification)
    # "verify-ca" - Always SSL (verify that the certificate presented by the
    # server was signed by a trusted CA)
    # "verify-full" - Always SSL (verify that the certification presented by the
    # server was signed by a trusted CA and the server host name matches the one
    # in the certificate)
    ## sslmode: "disable"
    sslmode: "require"
  # The maximum number of connections in the idle connection pool per pod (core+exporter).
  # If it <=0, no idle connections are retained.
  maxIdleConns: 100
  # The maximum number of open connections to the database per pod (core+exporter).
  # If it <= 0, then there is no limit on the number of open connections.
  # Note: the default number of connections is 1024 for postgre of harbor.
  maxOpenConns: 900
  ## Additional deployment annotations
  podAnnotations: {}

In kubernetes my harbor-core deployment returns the following

*resource: {2} severity: "INFO" textPayload: "2023-04-24T06:22:25Z [INFO] [/common/dao/base.go:66]: Registering database: type-PostgreSQL host-xxx.xx.xxx.x port-xxxx database-registry sslmode-"require"" timestamp: "2023-04-24T06:22:25.501442827Z"

resource: {2} severity: "INFO" textPayload: "[ORM]2023/04/24 06:22:25 register db Ping default, pq: connection requires a valid client certificate" timestamp: "2023-04-24T06:22:25.517334631Z"*

I could not find anything where to set the client certificate.