> For the complete documentation index, see [llms.txt](https://brightercommand.gitbook.io/paramore-brighter-documentation/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://brightercommand.gitbook.io/paramore-brighter-documentation/outbox-and-inbox/distributedlock/mongodbdistributedlock.md).

# MongoDB Distributed Lock

The MongoDB locking provider implements Brighter's distributed lock by writing lock documents to a MongoDB collection, so a single Outbox Sweeper and Archiver run when you scale out.

> **Reference** · Applies to **Brighter V10**

The MongoDB locking provider implements Brighter's [distributed lock](/paramore-brighter-documentation/outbox-and-inbox/distributedlock.md) by writing lock documents to a MongoDB collection, so a single [Outbox Sweeper](/paramore-brighter-documentation/outbox-and-inbox/brighteroutboxsupport.md#implicit-clear) and Archiver run when you scale out. It pairs naturally with the [MongoDB Outbox](/paramore-brighter-documentation/outbox-and-inbox/brighteroutboxsupport/mongodboutbox.md).

## MongoDB Distributed Lock Package

* **Paramore.Brighter.Locking.MongoDb**

The provider stores its locks in a collection that you name through the MongoDB configuration — see [Provisioning](#mongodb-distributed-lock-provisioning).

## MongoDB Distributed Lock Configuration

The MongoDB provider is configured through an `IAmAMongoDbConfiguration`, the same configuration type used by the MongoDB Outbox. Set its `Locking` property to a `MongoDbCollectionConfiguration` that names the lock collection and, optionally, a time-to-live for lock documents:

```csharp
var configuration = new MongoDbConfiguration(
    connectionString: "mongodb://localhost:27017",
    databaseName: "orders")
{
    Locking = new MongoDbCollectionConfiguration
    {
        Name = "brighter_locks",
        TimeToLive = TimeSpan.FromMinutes(1)
    }
};

var lockingProvider = new MongoDbLockingProvider(configuration);
```

`MongoDbLockingProvider` also has a constructor that accepts an `IAmAMongoDbConnectionProvider` alongside the configuration if you want to share a connection provider.

The lock has no options type of its own. `MongoDbConfiguration` and the `MongoDbCollectionConfiguration` you assign to `Locking` are documented once, on the Outbox page: see [MongoDB Outbox Options](/paramore-brighter-documentation/outbox-and-inbox/brighteroutboxsupport/mongodboutbox.md#mongodb-outbox-options). The two that matter here are `Locking.Name`, which names the collection holding the lock documents, and `Locking.TimeToLive`, which expires them through a MongoDB TTL index.

## MongoDB Distributed Lock Example

```csharp
var configuration = new MongoDbConfiguration("mongodb://localhost:27017", "orders")
{
    Locking = new MongoDbCollectionConfiguration { Name = "brighter_locks", TimeToLive = TimeSpan.FromMinutes(1) }
};

services
    .AddBrighter()
    .AddProducers(opt =>
    {
        opt.Outbox = /* your MongoDB Outbox */;
        // ... connection/transaction providers for your Outbox ...

        opt.DistributedLock = new MongoDbLockingProvider(configuration);
    })
    .UseOutboxSweeper(opt => { opt.BatchSize = 10; });
```

## MongoDB Distributed Lock Provisioning

The provider writes lock documents to the collection named by `Locking.Name` and relies on a unique index on the resource so only one instance can hold a given lock. If you set `TimeToLive`, a TTL index expires stale lock documents automatically, which protects you if an instance crashes before releasing its lock. Ensure the application's MongoDB user can create the collection and its indexes, or create them ahead of time.

## MongoDB Distributed Lock Notes

* Set `TimeToLive` longer than a typical Sweeper or Archiver batch so a lock is not expired mid-run. See [Lease Expiry vs Manual Release](/paramore-brighter-documentation/outbox-and-inbox/distributedlock.md#lease-expiry-vs-manual-release).
* Point the provider at the same MongoDB database as your Outbox so the Sweeper, Archiver, and lock share infrastructure.

## Further Reading

* [Distributed Lock](/paramore-brighter-documentation/outbox-and-inbox/distributedlock.md) — concepts and the full provider list
* [MongoDB Outbox](/paramore-brighter-documentation/outbox-and-inbox/brighteroutboxsupport/mongodboutbox.md) — the matching Outbox
* [Outbox Support](/paramore-brighter-documentation/outbox-and-inbox/brighteroutboxsupport.md) — the Sweeper and Archiver


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