Function build_storage 

pub fn build_storage(
    cfg: &AcmeConfig,
    resources: &Arc<PluginResources>,
) -> Result<Arc<dyn CertStorage>, AcmeError>

Builds the configured CertStorage. The redis backend keeps only the store’s name and resolves its client from resources on every call, so an Admin API store edit is picked up by the next operation; the name is validated here (resolved once and discarded) so a typo fails startup rather than every later renewal.