Introduce spring.data.mongodb.protocol to allow the MongoDB protocol to be customized when not using spring.data.mongodb.uri

[storyzero]

https://github.com/spring-projects/spring-boot/blob/main/spring-boot-project/spring-boot-autoconfigure/src/main/java/org/springframework/boot/autoconfigure/mongo/PropertiesMongoConnectionDetails.java#L51

I can't generate a connection string with mongodb+srv:// because PropertiesMongoConnectionDetails is hardcoded to use mongodb://
MongoProperties should be able to specify the protocol, and PropertiesMongoConnectionDetails should generate the connection string using the specified protocol.

[wilkinsona]

This is similar to #17215, but the proposal there was to inject the separate properties into the URI. This was rejected as it would be a breaking change that would prevent the URI being used to override any other settings. We can consider introducing a protocol property for those who prefer to use the separate properties. It would be ignored when spring.data.mongodb.uri is specified.

In the meantime, please note that you can specify mongodb+srv as the protocol but, to do so, you must use spring.data.mongodb.uri to provide all of the connection information. When configuring the URI you can reference other properties if you wish:

example.mongodb.username=alice
example.mongodb.password=secret
spring.data.mongodb.uri=mongodb+srv://${example.mongodb.username}:${example.mongodb.password}@mongo.example/testdb

[storyzero]

@wilkinsona
Thank you for your response.
To elaborate more on my situation, I want to use spring-cloud-vault-config-databases to auto-configure spring.data.mongodb.username and password. For security reasons, it is mandatory. Similarly, using mongodb+srv is also mandatory.

The example you provided seems worth trying, but the approach I was considering until just now was to manually configure everything, from the connection string to MongoTemplate, without any auto-configuration, using Vault.

However, it's a bit unfortunate that mongodb+srv can't be used unless it's through the URI.

[mhalbritter]

Superseded by #44366.