Unable to parse Connection String in multi hostname MongoDB

Bug description

Cannot connect successfully to mongodb when using a URL with a replica set specified.

• Removing the repeated host:port portion(s) for the replica set and instead just setting a single node works fine.
• The full URL with the replica set works fine when used with mongo on the command line.

Further details: A new project using Prisma 3.9.1 (https://registry.yarnpkg.com/prisma/-/prisma-3.9.1.tgz#7510a8bf06018a5313b9427b1127ce4750b1ce5c)

My mongodb connection URL, as printed from process.env.DATABASE_URL within my running program is as per the following (with some bits redacted, obviously).

This works perfectly if I connect using mongo on the command line.

When running in node and using const prisma = new PrismaClient(); I get the following error:

(node:50866) UnhandledPromiseRejectionWarning: Error: The provided database string is invalid. Unable to parse URL. in database URL. Please refer to the documentation in [https://www.prisma.io/docs/reference/database-reference/connection-urls]() for constructing a correct connection string. In some cases, certain characters must be escaped. Please check the string for any illegal characters.
    at [/path/to/my/app/project/node_modules/]()@prisma[/client/runtime/index.js:36300:21]()

When running npx prisma db pull --force using the CLI I get a different error:

project (main*) » npx prisma db pull --force                                                                                                                                                                                            Prisma schema loaded from prisma/schema.prisma
Environment variables loaded from .env
Datasource "db"

Introspecting based on datasource defined in prisma/schema.prisma …

Error: invalid port number in database URL

My database URL, as printed to the console via process.env.DATABASE_URL immediately prior to initing the PrismaClient is as follows:

mongodb://user:[e-mail]:27017,my-shard-01.atlas.mongodb.net:27017,my-shard-02.atlas.mongodb.net:27017/database?ssl=true&replicaSet=atlas-xxxxx-shard-0&authSource=admin&retryWrites=true

How to reproduce

1. Follow the Prisma getting started guide to create a new project using Mongo, from here.
2. Use a Mongo Atlas connection URL with a replica set
3. Cannot connect either via the prisma CLI tool or using the Prisma Client from within node.

Expected behavior

To be able to connect to a replica set.

Prisma information

From schema.prisma:

generator client {
  provider        = "prisma-client-js"
  previewFeatures = ["mongoDb"]
}

datasource db {
  provider = "mongodb"
  url      = env("DATABASE_URL")
}

Environment & setup

• OS: MacOS 12.1
• Database: Mongodb Atlas
• Node.js version: v14.19.0

Prisma Version

prisma                  : 3.9.1
@prisma/client          : 3.9.1
Current platform        : darwin
Query Engine (Node-API) : libquery-engine bcc2ff906db47790ee902e7bbc76d7ffb1893009 (at node_modules/@prisma/engines/libquery_engine-darwin.dylib.node)
Migration Engine        : migration-engine-cli bcc2ff906db47790ee902e7bbc76d7ffb1893009 (at node_modules/@prisma/engines/migration-engine-darwin)
Introspection Engine    : introspection-core bcc2ff906db47790ee902e7bbc76d7ffb1893009 (at node_modules/@prisma/engines/introspection-engine-darwin)
Format Binary           : prisma-fmt bcc2ff906db47790ee902e7bbc76d7ffb1893009 (at node_modules/@prisma/engines/prisma-fmt-darwin)
Default Engines Hash    : bcc2ff906db47790ee902e7bbc76d7ffb1893009
Studio                  : 0.457.0
Preview Features        : mongoDb

[matthewmueller]

Thanks for the comments. I now agree we should support the multi hostname URL format.

My main concern was even if we supported it, your MongoDB version would be too old. We support MongoDB 4.2+ though so once we support this URL format, Prisma should work for you!

[Jolg42]

@matthewmueller It sounds to me that the DNS Seed list (with +srv):

• is something Atlas does by default but
• is optional
• some hosts / custom hosting might not support it / not implement it

So the standard connection string format here always works, and we should support it.