add GCP information for mongodb

Author: nullfunc

docs/concepts/managed-storage/managed-mongodb.md

@@ -7,7 +7,7 @@ sidebar_position: 3000
 # Managed MongoDB
 
 :::info
-This feature was introduced in Defang v1.2.0 released on June 3, 2025. [Upgrade to the latest version](/docs/cli/defang_upgrade)
+This feature was introduced in Defang v1.2.0 released on June 3, 2025 for AWS. [Upgrade to the latest version](/docs/cli/defang_upgrade)
 :::
 
 Managed MongoDB is a service that allows you to store and retrieve large amounts of data in a document-oriented format. MongoDB is ideal for storing unstructured data like JSON documents, making it a popular choice for modern applications.
@@ -19,17 +19,39 @@ Managed MongoDB is a service that allows you to store and retrieve large amounts
 | [Playground](/docs/providers/playground#managed-services) | ⚠️ Unmanaged |
 | [AWS](/docs/providers/aws#managed-storage) | ✅ DocumentDB |
 | [DigitalOcean](/docs/providers/digitalocean#future-improvements) | ⚠️ Unmanaged |
-| [GCP](/docs/providers/gcp#future-improvements) | ⚠️ Unmanaged |
+| [GCP](/docs/providers/gcp#future-improvements) | ✅ Firestore |
 
 ## How to use Managed MongoDB
 
 To use managed MongoDB, in your `compose.yaml` file, use the `x-defang-mongodb` extension to define your MongoDB service. Adding the extension will tell Defang to provision a managed instance, rather than running MongoDB as a container.
 
 ### Required Configuration
 
-When using managed MongoDB, you **must** set a username and password for the database. By default, these are read from the `MONGO_INITDB_ROOT_USERNAME` and `MONGO_INITDB_ROOT_PASSWORD` config variables, conform [the official MongoDB container image](https://hub.docker.com/_/mongo). These can be set using the `defang config set MONGO_INITDB_ROOT_USERNAME` and `defang config set MONGO_INITDB_ROOT_PASSWORD` commands. If you do not provide these values, the deployment will fail.
+### AWS
+When using managed MongoDB on AWS, you **must** set a username and password for the database. By default, these are read from the `MONGO_INITDB_ROOT_USERNAME` and `MONGO_INITDB_ROOT_PASSWORD` config variables, following [the official MongoDB container image](https://hub.docker.com/_/mongo) convention.
 
-### Example
+You can set these using the following commands:
+
+```bash
+defang config set MONGO_INITDB_ROOT_USERNAME <your-username>
+defang config set MONGO_INITDB_ROOT_PASSWORD <your-password>
+```
+
+If you do not provide these values, the deployment will fail.
+
+### GCP
+
+When using managed MongoDB on GCP, you **must** set a `MONGO_INITDB_DATABASE` environment variable with the name of the database to create.
+
+```yaml
+services:
+  db:
+    x-defang-mongodb: true
+    environment:
+      MONGO_INITDB_DATABASE: mydb
+```
+
+**Important:** It's recommended that you **DO NOT** set `MONGO_INITDB_ROOT_USERNAME` and `MONGO_INITDB_ROOT_PASSWORD` config variables when using GCP. This is because GCP Firestore does not create default user accounts when creating MongoDB databases, and setting these credentials may cause connection issues.### Example
 
 ```yaml
 services:

docs/concepts/managed-storage/managed-storage.md

@@ -6,4 +6,4 @@ sidebar_position: 000
 
 # Managed Storage
 
-Defang helps you provision the infrastructure you need to run your services. That infrastructure is designed to scale in and out without persistent storage, so you can build highly scalable services. But Defang can also help you provision managed services to store and persist your data, like [caches](./managed-redis.md), [databases](./managed-postgres.mdx), and [object storage](./managed-object-storage.md).
+Defang helps you provision the infrastructure you need to run your services. That infrastructure is designed to scale in and out without persistent storage, so you can build highly scalable services. But Defang can also help you provision managed services to store and persist your data, like [caches](./managed-redis.md), [sql databases](./managed-postgres.mdx), [nosql databases](./managed-mongodb.md), and [object storage](./managed-object-storage.md).