OpenTelemetry and general metrics support for typescript generated prisma client

[vpmedia]

Feature Summary

After upgrading to Prisma 6.16.2 and client generated using the prisma-client provider, I can no longer query metrics using the preview feature.
I'm using MariaDb database adapter and it does not expose the relevant API either.

Use Cases & Problem Description

My schema file for reference:

generator client {
  provider               = "prisma-client"
  output                 = "../compiled"
  engineType             = "client"
  generatedFileExtension = "ts"
  importFileExtension    = "ts"
  moduleFormat           = "esm"
  runtime                = "nodejs"
}

Calling await prisma.$metrics.prometheus() raises a Method not implemented error.

Code reference for the raised exception:

prisma/packages/client/src/runtime/core/engines/client/ClientEngine.ts

Line 592 in 9b1a91b

throw new Error('Method not implemented.')

--

Checking at
https://github.com/prisma/prisma/tree/main/packages/instrumentation/src
I do not see any metrics related implementation, only for tracing. Since I'm using Open-Telemetry in my application, auto instrumentation would be the easiest choice.

--

Because I'm using the MariaDb database driver, I've also tried to collect metrics using it's API but it does not expose the required pool instance in order to do this.

const adapter = new PrismaMariaDb(connectionString);
const driver = await adapter.connect(); // instantiates a new PrismaMariaDbAdapter
const pool = driver.underlyingDriver(); // returns the mariadb.Pool instance

const getAdapterMetrics = () => {
    return {
        totalConnections: pool.totalConnections(),
        idleConnections: pool.idleConnections(),
        waitingConnections: pool.taskQueueSize(),
        activeConnections: pool.totalConnections() - pool.idleConnections(),
    };
};
console.log(getAdapterMetrics());

My issue with the code above is that if I understand the logic correctly it does create a new connection pool, but I would like to be able to query the PrismaClient.adapter.driver.pool which the Prisma MariaDb database adapter does not expose.

export declare class PrismaMariaDb implements SqlDriverAdapterFactory {
    #private;
    readonly provider = "mysql";
    readonly adapterName: string;
    constructor(config: mariadb.PoolConfig | string, options?: PrismaMariadbOptions);
    connect(): Promise<PrismaMariaDbAdapter>; // CREATES A NEW DB ADAPTER INSTANCE
}

declare class PrismaMariaDbAdapter extends MariaDbQueryable<mariadb.Pool> implements SqlDriverAdapter {
    private readonly capabilities;
    private readonly options?;
    constructor(client: mariadb.Pool, capabilities: Capabilities, options?: PrismaMariadbOptions | undefined);
    executeScript(_script: string): Promise<void>;
    getConnectionInfo(): ConnectionInfo;
    startTransaction(isolationLevel?: IsolationLevel): Promise<Transaction>;
    dispose(): Promise<void>;
    underlyingDriver(): mariadb.Pool; // THE POOL INSTANCE WHICH NEEDED FOR CONN METRICS
}

The ability to pass a Pool instance to the factory would also help to do this, refs:
#27992
#26885

--

Additionally the documentation related to metrics collection, post v6.16.2 (and future v7) Prisma Client version is missing, I'm only finding obsolete information about the deprecated metrics API.

Proposed Solution

• Expose the used adapter instance with pool in the generated PrismaClient instance
• Implement auto metrics instrumentation in the instrumentation pkg
• Update documentation how to collect metrics using the new client

Alternative Solutions

Potential Considerations

No response

Prisma Version

6.16.2

What part of Prisma does this affect?

Prisma Client

Additional Context

No response

Pre-Submission Checklist

• I have searched existing issues to make sure this is not a duplicate
• I have checked the Prisma roadmap to see if this is already planned
• I have described why this belongs in Prisma Core rather than a solution in application code

[FGoessler]

Hi @vpmedia 👋

This preview feature was deprecated with Prisma v6.14.0. We are not satisfied with its current approach and intend to create a better solution for the use-case in the future.
Due to this this preview feature was also never ported/implemented for the new prisma-client generator and our query compiler based architecture.

Maybe parts of your use case can still be covered with our support for tracing in combination with external aggregators like DataHog? See https://www.prisma.io/docs/orm/prisma-client/observability-and-logging/opentelemetry-tracing.

We are discussing exposing the underlying pool instance internally though (https://linear.app/prisma-company/issue/TML-1446/expose-pool-instance-of-driver-adapters). :)

[vpmedia]

@FGoessler Thank you for your feedback!
I'm all covered except connection pool metrics.
If you eventually decide to implement metrics in the Prisma instrumentation OTEL package, I would suggest to follow the latest official conventions:
https://github.com/open-telemetry/semantic-conventions/blob/v1.37.0/docs/database/database-metrics.md#connection-pools
But exposing the pool instance inside the Prisma client would be fine as well.

Best regards!