Create an Azure Function that connects to an Azure Cosmos DB

This Azure Functions sample script creates a function app and connects the function to an Azure Cosmos DB database. It makes the connection using an Azure Cosmos DB endpoint and access key that it adds to app settings. The created app setting that contains the connection can be used with an Azure Cosmos DB trigger or binding.

If you don't have an Azure subscription, create an Azure free account before you begin.

Prerequisites

• Use the Bash environment in Azure Cloud Shell. For more information, see Quickstart for Bash in Azure Cloud Shell.

  

• If you prefer to run CLI reference commands locally, install the Azure CLI. If you're running on Windows or macOS, consider running Azure CLI in a Docker container. For more information, see How to run the Azure CLI in a Docker container.

  • If you're using a local installation, sign in to the Azure CLI by using the az login command. To finish the authentication process, follow the steps displayed in your terminal. For other sign-in options, see Sign in with the Azure CLI.

  • When you're prompted, install the Azure CLI extension on first use. For more information about extensions, see Use extensions with the Azure CLI.

  • Run az version to find the version and dependent libraries that are installed. To upgrade to the latest version, run az upgrade.

Sample script

Launch Azure Cloud Shell

The Azure Cloud Shell is a free interactive shell that you can use to run the steps in this article. It has common Azure tools preinstalled and configured to use with your account.

To open the Cloud Shell, just select Try it from the upper right corner of a code block. You can also launch Cloud Shell in a separate browser tab by going to https://shell.azure.com.

When Cloud Shell opens, verify that Bash is selected for your environment. Subsequent sessions will use Azure CLI in a Bash environment, Select Copy to copy the blocks of code, paste it into the Cloud Shell, and press Enter to run it.

Sign in to Azure

Cloud Shell is automatically authenticated under the initial account signed-in with. Use the following script to sign in using a different subscription, replacing subscriptionId with your Azure subscription ID.

If you don't have an Azure subscription, create an Azure free account before you begin.

subscription="subscriptionId" # Set Azure subscription ID here

az account set -s $subscription # ...or use 'az login'

For more information, see set active subscription or log in interactively.

Run the script

# Function app and storage account names must be unique.

# Variable block
let "randomIdentifier=$RANDOM*$RANDOM"
location="eastus"
resourceGroup="msdocs-azure-functions-rg-$randomIdentifier"
tag="create-function-app-connect-to-cosmos-db"
storage="msdocsaccount$randomIdentifier"
functionApp="msdocs-serverless-function-$randomIdentifier"
skuStorage="Standard_LRS"
functionsVersion="4"

# Create a resource group
echo "Creating $resourceGroup in "$location"..."
az group create --name $resourceGroup --location "$location" --tags $tag

# Create a storage account for the function app. 
echo "Creating $storage"
az storage account create --name $storage --location "$location" --resource-group $resourceGroup --sku $skuStorage

# Create a serverless function app in the resource group.
echo "Creating $functionApp"
az functionapp create --name $functionApp --resource-group $resourceGroup --storage-account $storage --consumption-plan-location "$location" --functions-version $functionsVersion

# Create an Azure Cosmos DB database account using the same function app name.
echo "Creating $functionApp"
az cosmosdb create --name $functionApp --resource-group $resourceGroup

# Get the Azure Cosmos DB connection string.
endpoint=$(az cosmosdb show --name $functionApp --resource-group $resourceGroup --query documentEndpoint --output tsv)
echo $endpoint

key=$(az cosmosdb keys list --name $functionApp --resource-group $resourceGroup --query primaryMasterKey --output tsv)
echo $key

# Configure function app settings to use the Azure Cosmos DB connection string.
az functionapp config appsettings set --name $functionApp --resource-group $resourceGroup --setting CosmosDB_Endpoint=$endpoint CosmosDB_Key=$key

Clean up resources

Use the following command to remove the resource group and all resources associated with it using the az group delete command - unless you have an ongoing need for these resources. Some of these resources may take a while to create, as well as to delete.

az group delete --name $resourceGroup

Sample reference

Command	Notes
az group create	Create a resource group with location
az storage accounts create	Create a storage account
az functionapp create	Creates a function app in the serverless Consumption plan.
az cosmosdb create	Create an Azure Cosmos DB database.
az cosmosdb show	Gets the database account connection.
az cosmosdb keys list	Gets the keys for the database.
az functionapp config appsettings set	Sets the connection string as an app setting in the function app.

Next steps

For more information on the Azure CLI, see Azure CLI documentation.

More Azure Functions CLI script samples can be found in the Azure Functions documentation.