Configuring a DNS Private Resolver for Seamless Azure Cosmos DB Connectivity with Point-to-Site VPN

Introduction

This article will guide you through the setup of a DNS private resolver for Azure Cosmos DB, addressing the challenge of connecting to the database from different virtual networks or through VPNs. By configuring a DNS private resolver, you can ensure seamless and secure connectivity to your Azure Cosmos DB, enabling efficient data access, data restrictions, and management.

Problem:

When you add a private endpoint to Azure Cosmos DB, your client may not be able to connect to the database while connected to a VPN because the IP address of the database is not resolvable. Even with DNS integration enabled, connecting to the database from a different virtual network or through a VPN requires a DNS forwarder or another method to resolve the Fully Qualified Domain Name (FQDN) of the database.

Services Overview:

1. Azure Cosmos DB: A globally distributed, multi-model database service that offers consistent performance and availability. Azure Cosmos DB supports storing and querying data of any size and type, ranging from relational data to documents to JSON.
2. DNS Private Resolver: A server that resolves DNS queries for private resources in your Virtual Network (VNet). Configuring a DNS private resolver allows your client to resolve the IP address of your Azure Cosmos DB database and connect to it securely.
3. Private Endpoint: A network interface that facilitates private connections to Azure Cosmos DB from your VNet. When you create a private endpoint, Azure Cosmos DB generates a virtual network interface in your VNet that is connected to the Azure Cosmos DB service.
4. Private DNS Zone: A DNS zone hosted within your virtual network, enabling you to control how DNS queries for your private resources are resolved. You can create records for your private resources, such as Azure Cosmos DB databases, allowing clients to resolve their IP addresses without accessing the public internet.
5. Virtual Network (VNet): A logical isolation of your Azure resources, similar to a traditional network, but implemented in the cloud.
   
   

Diagram:

Solution:

To overcome the connectivity issue, you can configure a DNS private resolver. A DNS private resolver is a server that resolves DNS queries for private resources in your VNet, enabling your client to resolve the IP address of your Azure Cosmos DB database and connect to it securely.

Follow these steps to configure a DNS private resolver:

1. Go to the Azure portal and navigate to the DNS private resolvers blade.

2. Select Create DNS private resolver.

3. In the Create DNS private resolver blade, complete the following steps:

• In the Name field, enter a name for your DNS private resolver.
• In the Location field, select the location for your DNS private resolver.
• In the Resource group field, select the resource group for your DNS private resolver.
• Select the Subnet field and choose the subnet in your VNet where VPN is configured.
• Select Create.
  
  

Configuring the Inbound endpoint:

1. In the Settings section of DNS private resolver, select Inbound endpoints.

2. In the Inbound endpoints blade, select Add inbound endpoint.

3. Add the inbound endpoint.

Note: Ensure that the subnet you choose for the Inbound endpoint is in the same VNet where the VPN is configured.

Configure DNS IP:

Once the Inbound endpoint is created, you will see an IP address assigned to it from the selected subnet range. Copy this IP address and go to your VNET where VPN is configured. From the left panel, select DNS servers and add this IP as a custom DNS IP.

After completing these steps, when you connect to the VPN, you should see the same IP address as the DNS IP address in the VPN settings. Now you should be able to connect to Azure Cosmos DB while connected to the Azure Point-to-Site VPN.

If you have any questions you can reach out our SharePoint Consulting team here.

Overview on adding custom columns in Azure Cosmos DB

Introduction

We recently implemented a console application for a Postal and Parcel company based out of Melbourne, Victoria, Australia. In this, we have to store the user's login track details to a Cosmos DB. So we needed to add few custom columns in the Azure Cosmos DB container to store this type of information.

In this blog, we will look into the overall structure of the Cosmos DB container and we will be creating few custom columns also.

Solution

• The Cosmos DB is a schema-free and unstructured database. It means that we can store data without considering its format.
• The Cosmos DB has tables as containers for the database.
• The container stores data in JSON format. So, we can store JSON objects as an item in the container of Cosmos DB. 
• We can add any number of custom columns and their values as a JSON property.
• The Cosmos DB container requires only one mandatory property it's the Item ID ("id"). and the Item ID is a not null and unique field. It has 255 characters limit.

Creating an item with custom columns

First, we need to pass a JSON format object to create a new item as shown below. 

 {    

   "id": "1",    

   "User name": "Aniket Chauhan",    

   "Email Address": "aniket.chauhan@binaryrepublik.com",    

   "Logged Date Time": "2021-07-09T09:07:19.2825515Z",    

}   

Now when we save this new item it will be stored with some system-generated fields as shown below. 

Here, the User name, Email Address, and Logged Date Time properties are custom columns.

When we create an item in the cosmos DB container it generates 5 extra properties.

1. _rid: The resource ID (_rid) is a unique identifier that is used internally for navigation and placement of the resource.
2. _self: It is the unique addressable URI for the item.
3. _etag: Entity tag(_etag) used for optimistic concurrency control.
4. _attachments: It specifies the addressable path for the attachment resource.
5. _ts: It stores the timestamp of the last update of the item.

Note: We can also pass the GUID for the "id" field as per our requirement.

Conclusion

This is how we can add custom columns in Cosmos DB. Hope this helps, good day!

If you have any questions you can reach out our SharePoint Consulting team here.