MongoHealthIndicator uses isMaster command, which is not part of Mongo's stable API https://www.mongodb.com/docs/v5.0/reference/stable-api-changelog/

If the underlying Mongo connection is configured to use the stable API and strict setting, the health indicator yields an error, as Mongo rejects the isMaster command.

Affected versions: Tested with sprinboot 3.3.0, potentially since 3.0.0

To reproduce it, create a blank springboot project including spring-boot-starter-data-mongodb, spring-boot-starter-web and spring-boot-starter-actuator dependencies. Then, set up both Mongo stable API version and strict to true by creating the following bean:

    @Bean
    public MongoClientSettings mongoClientSettings() {
        return MongoClientSettings.builder()
            .applicationName("testApp")
            .serverApi(ServerApi.builder()
                .strict(true)
                .version(ServerApiVersion.V1)
                .build())
            .build();
    }

For reference, such project has been created here https://github.com/jorgelc/mongo-stable-api-springboot-health, with steps about how to reproduced the error and compare the behaviour with when strict is set to false.

Comment From: wilkinsona

Thank you. I've reproduced the problem.

I think we should switch to the hello command. It's supported in MongoDB 5.0 and later and Mongo 4.x reached end of life in February 2024.

Comment From: jorgelc

Thanks @wilkinsona

We implemented that as a temporary workaround locally and it worked for us, but it would be nice to have that supported out of the box.

Comment From: jyemin

Just FYI, the hello command was backported all the way to MongoDB 3.6, so this should be a safe change even for EOL'd MongoDB releases.

Comment From: pkunk

FYI: This is not compatible with Azure Cosmos MongoDB API: https://learn.microsoft.com/en-us/azure/cosmos-db/mongodb/feature-support-60#database-commands

Comment From: wilkinsona

Thanks, @pkunk, but I'm not sure there's much we can do about that. I don't see any mention of isMaster in the list of supported database commands either so it's not clear that this would have worked before. I'd recommend raising this with Microsoft to see if they can improve Cosmos' compliance with the MongoDB API.

In the meantime, anyone who's affected can work around the non-compliance by defining their own bean named mongoHealthIndicator or mongoHealthContributor.

Comment From: SimonedeGijt

We have the same @pkunk . Did you already raise this with Microsoft? Would be great if I can follow the progress on this item :)

Comment From: pkunk

We have the same @pkunk . Did you already raise this with Microsoft?

No. We just use custom mongoHealthIndicator bean.

Comment From: SimonedeGijt

I created a post now, would be great if many people can vote on it 😄 : https://feedback.azure.com/d365community/idea/c7b19748-9276-ef11-a4e6-000d3a059eeb

Comment From: gahl-levy

Hey @pkunk @SimonedeGijt @wilkinsona . I'm Gahl from the Cosmos DB Product Team. The hello command is already supported in Cosmos DB for MongoDB vCore and Cosmos DB for MongoDB RU. We're adding it to our docs now. Sorry for the confusion here and thanks for pointing this out!

Comment From: wilkinsona

Good news! Thanks very much, @gahl-levy.

Comment From: ashishrky

@gahl-levy is there any setting to enable hello command for Cosmos DB for MongoDB RU? I am running Spring Boot v3.3.4 application, and its actuator health endpoint is still failing with the error... 

        "mongo": {
            "status": "DOWN",
            "details": {
                "error": "org.springframework.dao.InvalidDataAccessApiUsageException: Command failed with error 115 (CommandNotSupported): 'Command hello not supported.' on server xxxxxxx-centralus.mongo.cosmos.azure.com:10255. The full response is {\"ok\": 0.0, \"errmsg\": \"Command hello not supported.\", \"code\": 115, \"codeName\": \"CommandNotSupported\"}"
            }
        },

My spring boot app is running in App Service, and everything is located in Central US data center.

Comment From: miguelrq

@gahl-levy looks like the way actuator does health checks is with mongoTemplate.executeCommand"{ hello: 1 }" which cosmosdb doesn't support

Against a mongo shell db.runCommand({isMaster:1}) //works db.runCommand({hello:1}) //doesn't work

Comment From: arm749

@wilkinsona @gahl-levy This issue should not be closed. The actuator health check still fails on a startup of Springboot 3.4.0 while using Azure Cosmos DB Mongo. This is breaking behavior for all Mongo CosmosDB users.

Comment From: wilkinsona

@arm749 Unfortunately, re-opening this issue won't achieve anything as there's no change that can be made in Spring Boot to improve the situation.

We do not want to switch back to { isMaster: 1 } as our health indicator when then be incompatible with Mongo's stable API, undoing the goal of this issue. We also can't affect CosmosDB's support for the stable API.

A workaround has already been suggested above:

In the meantime, anyone who's affected can work around the non-compliance by defining their own bean named mongoHealthIndicator or mongoHealthContributor.

I think this is the best that we can do on the Spring Boot side until Microsoft have a chance to clarify their support for Mongo's stable API.

Comment From: arm749

@wilkinsona Thanks. Is Microsoft aware of this? By the looks of above, it doesn't seem like they have any action items on this.

Comment From: wilkinsona

They should be given the existence of https://feedback.azure.com/d365community/idea/c7b19748-9276-ef11-a4e6-000d3a059eeb and @gahl-levy's involvement in this issue.

Comment From: kubav182

@gahl-levy is there any chance cosmos db will support db.runCommand({hello:1}) soon?

Comment From: dafnenavita

Hi @gahl-levy @thekid - is there a fix expected soon for this ? I see some developments but I’m still facing the same issue for any springboot version 3.2.7 and above