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Azure CosmosDB binding spec

Detailed documentation on the Azure CosmosDB binding component

Component format

To setup Azure CosmosDB binding create a component of type See this guide on how to create and apply a binding configuration.

kind: Component
  name: <NAME>
  namespace: <NAMESPACE>
  version: v1
  - name: url
    value: https://******
  - name: masterKey
    value: *****
  - name: database
    value: db
  - name: collection
    value: collection
  - name: partitionKey
    value: message

Spec metadata fields

Field Required Binding support Details Example
url Y Output The CosmosDB url "https://******"
masterKey Y Output The CosmosDB account master key "master-key"
database Y Output The name of the CosmosDB database "OrderDb"
collection Y Output The name of the container inside the database. "Orders"
partitionKey Y Output The name of the key to extract from the payload (document to be created) that is used as the partition key. This name must match the partition key specified upon creation of the Cosmos DB container. "OrderId", "message"

For more information see Azure Cosmos DB resource model.

Azure Active Directory (AAD) authentication

The Azure Cosmos DB binding component supports authentication using all Azure Active Directory mechanisms. For further information and the relevant component metadata fields to provide depending on the choice of AAD authentication mechanism, see the docs for authenticating to Azure.

Binding support

This component supports output binding with the following operations:

  • create

Best Practices for Production Use

Azure Cosmos DB shares a strict metadata request rate limit across all databases in a single Azure Cosmos DB account. New connections to Azure Cosmos DB assume a large percentage of the allowable request rate limit. (See the CosmosDB documentation)

Therefore several strategies must be applied to avoid simultaneous new connections to Azure Cosmos DB:

  • Ensure sidecars of applications only load the Azure Cosmos DB component when they require it to avoid unnecessary database connections. This can be done by scoping your components to specific applications.
  • Choose deployment strategies that sequentially deploy or start your applications to minimize bursts in new connections to your Azure Cosmos DB accounts.
  • Avoid reusing the same Azure Cosmos DB account for unrelated databases or systems (even outside of Dapr). Distinct Azure Cosmos DB accounts have distinct rate limits.
  • Increase the initTimeout value to allow the component to retry connecting to Azure Cosmos DB during side car initialization for up to 5 minutes. The default value is 5s and should be increased. When using Kubernetes, increasing this value may also require an update to your Readiness and Liveness probes.
  version: v1
  initTimeout: 5m

Data format

The output binding create operation requires the following keys to exist in the payload of every document to be created:

  • id: a unique ID for the document to be created
  • <partitionKey>: the name of the partition key specified via the spec.partitionKey in the component definition. This must also match the partition key specified upon creation of the Cosmos DB container.