Exercise - Use data volumes

10 minutes

By default, Azure Container Instances are stateless. If the container crashes or stops, all of its state is lost. To persist state beyond the lifetime of the container, you must mount a volume from an external store.

Mount an Azure file share to an Azure container instance so that you can store data and access it later.

Create a storage account and a file share. Later, you can make the file share accessible to an Azure container instance.

Your storage account requires a unique name. For learning purposes, run the following command to store a unique name in a Bash variable:
```
STORAGE_ACCOUNT_NAME=mystorageaccount$RANDOM
```

Run the following az storage account create command to create your storage account:

az storage account create \
  --resource-group learn-deploy-aci-rg \
  --name $STORAGE_ACCOUNT_NAME \
  --sku Standard_LRS \
  --location eastus

Run the following command to place the storage account connection string into an environment variable named AZURE_STORAGE_CONNECTION_STRING:
```
export AZURE_STORAGE_CONNECTION_STRING=$(az storage account show-connection-string \
  --resource-group learn-deploy-aci-rg \
  --name $STORAGE_ACCOUNT_NAME \
  --output tsv)
```
AZURE_STORAGE_CONNECTION_STRING is a special environment variable that the Azure CLI understands. The export part makes this variable accessible to other CLI commands that you run later.
Run this command to create a file share named aci-share-demo in the storage account:
```
az storage share create --name aci-share-demo
```

Get storage credentials

To mount an Azure file share as a volume in Azure Container Instances, you need these three values:

Storage account name
Share name
Storage account access key

You already have the first two values. The storage account name is stored in the STORAGE_ACCOUNT_NAME Bash variable. You specified aci-share-demo as the share name in the previous step. Here, you get the remaining value: the storage account access key.

Run the following command to get the storage account key:

STORAGE_KEY=$(az storage account keys list \
  --resource-group learn-deploy-aci-rg \
  --account-name $STORAGE_ACCOUNT_NAME \
  --query "[0].value" \
  --output tsv)

The result is stored in a Bash variable named STORAGE_KEY.

As an optional step, print the storage key to the console.
```
echo $STORAGE_KEY
```

To mount an Azure file share as a volume in a container, you specify the share and volume mount point when you create the container.

Run this az container create command to create a container that mounts /aci/logs/ to your file share:

az container create \
  --resource-group learn-deploy-aci-rg \
  --name aci-demo-files \
  --image mcr.microsoft.com/azuredocs/aci-hellofiles \
  --location eastus \
  --ports 80 \
  --ip-address Public \
  --azure-file-volume-account-name $STORAGE_ACCOUNT_NAME \
  --azure-file-volume-account-key $STORAGE_KEY \
  --azure-file-volume-share-name aci-share-demo \
  --azure-file-volume-mount-path /aci/logs/

Run az container show to get your container's public IP address:

az container show \
  --resource-group learn-deploy-aci-rg \
  --name aci-demo-files \
  --query ipAddress.ip \
  --output tsv

From a browser, navigate to your container's IP address. You get this page:
Enter some text into the form, and select Submit. This action creates a file that contains the text you entered in the Azure file share.
Run this az storage file list command to display the files that are contained in your file share:
```
az storage file list -s aci-share-demo -o table
```
Run az storage file download to download a file to your Cloud Shell session. Replace <filename> with one of the files that appeared in the previous step:
```
az storage file download -s aci-share-demo -p <filename>
```
Run the cat command to print the contents of the file.
```
cat <filename>
```

Remember that your data persists when your container exits. You can mount your file share to other container instances to make that data available to them.

Exercise - Use data volumes

Create an Azure file share

Get storage credentials

Deploy a container and mount the file share

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