Configure Second Entity Manager for Symfony5 Bundle Entities - symfony

Question

I'd like to have 2 entity managers, one for a SQLite database for entities defined in a bundle, and the other for the main application. That way, I can load the data that never changes into one database, and load fixtures, tests, etc. into the application database. I'd expect the following to dump the sql for the bundle entities, but it doesn't:
bin/console doctrine:schema:update --dump-sql --em=geonames
[OK] No Metadata Classes to process.
Similarly, I would expect easyadmin to let me define classes to the bundle entities, but it also fails.
# easy_admin.yaml
entities:
Administrative:
class: Bordeux\Bundle\GeoNameBundle\Entity\Administrative
The configured class
"Bordeux\Bundle\GeoNameBundle\Entity\Administrative" for the path
"easy_admin.entities.Administrative" is no mapped entity.
I expect it has something to do with namespaces, or maybe the is_bundle parameter. I've spent a few hours hacking at this, following along with the tutorials and documentation about multiple entity managers, but I can't find anything that shows how to handle entities that come from a third-party bundle.
# doctrine.yaml
doctrine:
dbal:
default_connection: default
connections:
default:
url: '%env(resolve:DATABASE_URL)%'
geonames:
url: '%env(DATABASE_GEONAMES_URL)%'
orm:
default_entity_manager: default
entity_managers:
default:
connection: default
naming_strategy: doctrine.orm.naming_strategy.underscore_number_aware
auto_mapping: true
mappings:
App:
is_bundle: false
type: annotation
dir: '%kernel.project_dir%/src/Entity'
prefix: 'App\Entity'
alias: App
geonames:
connection: geonames
mappings:
BordeuxGeoNameBundle:
is_bundle: true
type: annotation
dir: 'Entity'
prefix: 'Geonames\Entity'
alias: Geonames

Answer 1

I have not configured multiple entity managers for the latest and greatest Symfony versions so I setup a little test case and came up with this for a configuration:
orm:
default_entity_manager: default
auto_generate_proxy_classes: true
entity_managers:
default:
connection: default
naming_strategy: doctrine.orm.naming_strategy.underscore_number_aware
mappings:
App:
is_bundle: false
type: annotation
dir: '%kernel.project_dir%/src/Entity'
prefix: 'App\Entity'
alias: App
geonames:
connection: geonames
naming_strategy: doctrine.orm.naming_strategy.underscore_number_aware
mappings:
BordeuxGeoNameBundle:
is_bundle: true
type: annotation
dir: 'Entity'
prefix: 'Bordeux\Bundle\GeoNameBundle\Entity'
alias: GeoNames
I tested it using:
bin/console doctrine:mapping:info --em=geonames
And confirmed the entities were being mapped. I did not install EasyAdmin and test it but I don't see any reason why it would not work.
The main difference was using the entity namespace for the prefix attribute.
And just for my own future reference, I committed the test project to github.