Azure Functions in Java with an Event Hub trigger and Cosmos DB output binding

Code Sample
11/20/2020

Shows how to use Azure Functions with Java to handle Event Hub events and store analysis results in a Cosmos DB database.

This sample accompanies Tutorial: Create an Azure function in Java with an Event Hub trigger and Cosmos DB output binding.

The commands below use a Bash environment. Equivalent commands for the Windows Cmd environment are provided in the tutorial.

Prerequisites

Setup

Navigate to the folder containing the repo and run the following commands. Replace the <value> placeholders with appropriate resource names and location.

RESOURCE_GROUP=<value>
EVENT_HUB_NAMESPACE=<value>
EVENT_HUB_NAME=<value>
EVENT_HUB_AUTHORIZATION_RULE=<value>
COSMOS_DB_ACCOUNT=<value>
STORAGE_ACCOUNT=<value>
FUNCTION_APP=<value>
LOCATION=<value>

az group create \
    --name $RESOURCE_GROUP \
    --location $LOCATION

az eventhubs namespace create \
    --resource-group $RESOURCE_GROUP \
    --name $EVENT_HUB_NAMESPACE
az eventhubs eventhub create \
    --resource-group $RESOURCE_GROUP \
    --name $EVENT_HUB_NAME \
    --namespace-name $EVENT_HUB_NAMESPACE \
    --message-retention 1
az eventhubs eventhub authorization-rule create \
    --resource-group $RESOURCE_GROUP \
    --name $EVENT_HUB_AUTHORIZATION_RULE \
    --eventhub-name $EVENT_HUB_NAME \
    --namespace-name $EVENT_HUB_NAMESPACE \
    --rights Listen Send

az cosmosdb create \
    --resource-group $RESOURCE_GROUP \
    --name $COSMOS_DB_ACCOUNT
az cosmosdb sql database create \
    --resource-group $RESOURCE_GROUP \
    --account-name $COSMOS_DB_ACCOUNT \
    --name TelemetryDb
az cosmosdb sql container create \
    --resource-group $RESOURCE_GROUP \
    --account-name $COSMOS_DB_ACCOUNT \
    --database-name TelemetryDb \
    --name TelemetryInfo \
    --partition-key-path '/temperatureStatus'

az storage account create \
    --resource-group $RESOURCE_GROUP \
    --name $STORAGE_ACCOUNT \
    --sku Standard_LRS
az functionapp create \
    --resource-group $RESOURCE_GROUP \
    --name $FUNCTION_APP \
    --storage-account $STORAGE_ACCOUNT \
    --consumption-plan-location $LOCATION \
    --runtime java \
    --functions-version 2

AZURE_WEB_JOBS_STORAGE=$( \
    az storage account show-connection-string \
        --name $STORAGE_ACCOUNT \
        --query connectionString \
        --output tsv)
echo $AZURE_WEB_JOBS_STORAGE
EVENT_HUB_CONNECTION_STRING=$( \
    az eventhubs eventhub authorization-rule keys list \
        --resource-group $RESOURCE_GROUP \
        --name $EVENT_HUB_AUTHORIZATION_RULE \
        --eventhub-name $EVENT_HUB_NAME \
        --namespace-name $EVENT_HUB_NAMESPACE \
        --query primaryConnectionString \
        --output tsv)
echo $EVENT_HUB_CONNECTION_STRING
COSMOS_DB_CONNECTION_STRING=$( \
    az cosmosdb keys list \
        --resource-group $RESOURCE_GROUP \
        --name $COSMOS_DB_ACCOUNT \
        --type connection-strings \
        --query connectionStrings[0].connectionString \
        --output tsv)
echo $COSMOS_DB_CONNECTION_STRING

az functionapp config appsettings set \
    --resource-group $RESOURCE_GROUP \
    --name $FUNCTION_APP \
    --settings \
        AzureWebJobsStorage=$AZURE_WEB_JOBS_STORAGE \
        EventHubConnectionString=$EVENT_HUB_CONNECTION_STRING \
        CosmosDBConnectionString=$COSMOS_DB_CONNECTION_STRING

mvn archetype:generate --batch-mode \
    -DarchetypeGroupId=com.microsoft.azure \
    -DarchetypeArtifactId=azure-functions-archetype \
    -DappName=$FUNCTION_APP \
    -DresourceGroup=$RESOURCE_GROUP \
    -DgroupId=com.example \
    -DartifactId=telemetry-functions

cd telemetry-functions
rm -r src/test

func azure functionapp fetch-app-settings $FUNCTION_APP

Running the sample

Run the sample locally:

mvn clean package
mvn azure-functions:run

Deploy to Azure:

mvn azure-functions:deploy

Clean up Azure resources when you are finished:

az group delete --name $RESOURCE_GROUP

Key concepts

For details, see Tutorial: Create an Azure function in Java with an Event Hub trigger and Cosmos DB output binding.

Contributing

This project welcomes contributions and suggestions. Most contributions require you to agree to a Contributor License Agreement (CLA) declaring that you have the right to, and actually do, grant us the rights to use your contribution. For details, visit https://cla.opensource.microsoft.com.

When you submit a pull request, a CLA bot will automatically determine whether you need to provide a CLA and decorate the PR appropriately (e.g., status check, comment). Simply follow the instructions provided by the bot. You will only need to do this once across all repos using our CLA.

This project has adopted the Microsoft Open Source Code of Conduct. For more information see the Code of Conduct FAQ or contact opencode@microsoft.com with any additional questions or comments.

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