Tutorial: Deploy a background processing application with Azure Container Apps Preview

Azure Container Apps allows you to deploy applications without requiring the exposure of public endpoints. In this tutorial, you deploy a sample application that reads messages from an Azure Storage Queue and logs the messages in Azure log Analytics workspace. Using Container Apps scale rules, the application can scale up and down based on the Azure Storage queue length. When there are no messages on the queue, the container app scales down to zero.

You learn how to:

  • Create a Container Apps environment to deploy your container apps
  • Create an Azure Storage Queue to send messages to the container app
  • Deploy your background processing application as a container app
  • Verify that the queue messages are processed by the container app

Prerequisites

The following items are required to complete this tutorial:

  • Azure CLI: You must have Azure CLI version 2.29.0 or later installed on your local computer.

Setup

This tutorial makes use of the following environment variables:

RESOURCE_GROUP="my-containerapps"
LOCATION="canadacentral"
CONTAINERAPPS_ENVIRONMENT="containerapps-env"
LOG_ANALYTICS_WORKSPACE="containerapps-logs"

Create a variable for your storage account name.

STORAGE_ACCOUNT="<MY_STORAGE_ACCOUNT_NAME>"

Replace the <storage account name> placeholder with your own value before you run this snippet. Storage account names must be unique within Azure, be between 3 and 24 characters in length, and may contain numbers or lowercase letters only. The storage account will be created in a following step.

Next, sign in to Azure from the CLI.

Run the following command, and follow the prompts to complete the authentication process.

az login

To ensure you're running the latest version of the CLI, use the upgrade command.

az upgrade

Next, install the Azure Container Apps extension to the CLI.

az extension add \
  --source https://workerappscliextension.blob.core.windows.net/azure-cli-extension/containerapp-0.2.0-py2.py3-none-any.whl

Now that the extension is installed, register the Microsoft.Web namespace.

az provider register --namespace Microsoft.Web

You'll use a resource group to organize the services related to your new container app. Create the group with the following command:

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

With the CLI upgraded and a new resource group available, you can create a Container Apps environment and deploy your container app.

Create an environment

Azure Container Apps environments act as secure boundary around a group of container apps. Different container apps in the same environment are deployed in the same virtual network and write logs to the same Log Analytics workspace.

Azure Log Analytics is used to monitor your container app required when creating a Container Apps environment.

Create a new Log Analytics workspace with the following command:

az monitor log-analytics workspace create \
  --resource-group $RESOURCE_GROUP \
  --workspace-name $LOG_ANALYTICS_WORKSPACE

Next, retrieve the Log Analytics Client ID and client secret. Make sure to run each query separately to give enough time for the request to complete.

LOG_ANALYTICS_WORKSPACE_CLIENT_ID=`az monitor log-analytics workspace show --query customerId -g $RESOURCE_GROUP -n $LOG_ANALYTICS_WORKSPACE --out json | tr -d '"'`

LOG_ANALYTICS_WORKSPACE_CLIENT_SECRET=`az monitor log-analytics workspace get-shared-keys --query primarySharedKey -g $RESOURCE_GROUP -n $LOG_ANALYTICS_WORKSPACE --out json | tr -d '"'`

Individual container apps are deployed to an Azure Container Apps environment. To create the environment, run the following command:

az containerapp env create \
  --name $CONTAINERAPPS_ENVIRONMENT \
  --resource-group $RESOURCE_GROUP \
  --logs-workspace-id $LOG_ANALYTICS_WORKSPACE_CLIENT_ID \
  --logs-workspace-key $LOG_ANALYTICS_WORKSPACE_CLIENT_SECRET \
  --location "$LOCATION"

Set up a storage queue

Create an Azure Storage account.

az storage account create \
  --name $STORAGE_ACCOUNT \
  --resource-group $RESOURCE_GROUP \
  --location "$LOCATION" \
  --sku Standard_RAGRS \
  --kind StorageV2

Next, get the queue's connection string.

QUEUE_CONNECTION_STRING=`az storage account show-connection-string -g $RESOURCE_GROUP --name $STORAGE_ACCOUNT --query connectionString --out json | tr -d '"'`

Now you can create the message queue.

az storage queue create \
  --name "myqueue" \
  --account-name $STORAGE_ACCOUNT \
  --connection-string $QUEUE_CONNECTION_STRING

Finally, you can send a message to the queue.

az storage message put \
  --content "Hello Queue Reader App" \
  --queue-name "myqueue" \
  --connection-string $QUEUE_CONNECTION_STRING

Deploy the background application

Create a file named queue.json and paste the following configuration code into the file.

{
    "$schema": "https://schema.management.azure.com/schemas/2019-08-01/deploymentTemplate.json#",
    "contentVersion": "1.0.0.0",
    "parameters": {
        "location": {
            "defaultValue": "canadacentral",
            "type": "String"
        },
        "environment_name": {
            "defaultValue": "",
            "type": "String"
        },
        "queueconnection": {
            "defaultValue": "",
            "type": "String"
        }
    },
    "variables": {},
    "resources": [
    {
        "name": "queuereader",
        "type": "Microsoft.Web/containerApps",
        "apiVersion": "2021-03-01",
        "kind": "containerapp",
        "location": "[parameters('location')]",
        "properties": {
            "kubeEnvironmentId": "[resourceId('Microsoft.Web/kubeEnvironments', parameters('environment_name'))]",
            "configuration": {
                "activeRevisionsMode": "single",
                "secrets": [
                {
                    "name": "queueconnection",
                    "value": "[parameters('queueconnection')]"
                }]
            },
            "template": {
                "containers": [
                    {
                        "image": "mcr.microsoft.com/azuredocs/containerapps-queuereader",
                        "name": "queuereader",
                        "env": [
                            {
                                "name": "QueueName",
                                "value": "myqueue"
                            },
                            {
                                "name": "QueueConnectionString",
                                "secretref": "queueconnection"
                            }
                        ]
                    }
                ],
                "scale": {
                    "minReplicas": 1,
                    "maxReplicas": 10,
                    "rules": [
                        {
                            "name": "myqueuerule",
                            "azureQueue": {
                                "queueName": "myqueue",
                                "queueLength": 100,
                                "auth": [
                                    {
                                        "secretRef": "queueconnection",
                                        "triggerParameter": "connection"
                                    }
                                ]
                            }
                        }
                    ]
                }
            }
        }
    }]
}

Now you can create and deploy your container app.

az deployment group create --resource-group "$RESOURCE_GROUP" \
  --template-file ./queue.json \
  --parameters \
    environment_name="$CONTAINERAPPS_ENVIRONMENT" \
    queueconnection="$QUEUE_CONNECTION_STRING" \
    location="$LOCATION"

This command deploys the demo application from the public container image called mcr.microsoft.com/azuredocs/containerapps-queuereader and sets secrets and environments variables used by the application.

The application scales up to 10 replicas based on the queue length as defined in the scale section of the ARM template.

Verify the result

The container app running as a background process creates logs entries in Log analytics as messages arrive from Azure Storage Queue. You may need to wait a few minutes for the analytics to arrive for the first time before you are able to query the logged data.

Run the following command to see logged messages. This command requires the Log analytics extension, so accept the prompt to install extension when requested.

az monitor log-analytics query \
  --workspace $LOG_ANALYTICS_WORKSPACE_CLIENT_ID \
  --analytics-query "ContainerAppConsoleLogs_CL | where ContainerAppName_s == 'queuereader' and Log_s contains 'Message ID'" \
  --out table

Tip

Having issues? Let us know on GitHub by opening an issue in the Azure Container Apps repo.

Clean up resources

Once you are done, clean up your Container Apps resources by running the following command to delete your resource group.

az group delete \
  --resource-group $RESOURCE_GROUP

This command deletes the entire resource group including the Container Apps instance, storage account, Log Analytics workspace, and any other resources in the resource group.