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Mount an Azure file share in Azure Container Instances

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By default, Azure Container Instances are stateless. If the container is restarted, 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. As shown in this article, Azure Container Instances can mount an Azure file share created with Azure Files. Azure Files offers fully managed file shares hosted in Azure Storage that are accessible via the industry standard Server Message Block (SMB) protocol. Using an Azure file share with Azure Container Instances provides file-sharing features similar to using an Azure file share with Azure virtual machines.

Limitations

  • You can only mount Azure Files shares to Linux containers. Review more about the differences in feature support for Linux and Windows container groups in the overview.
  • Azure file share volume mount requires the Linux container run as root .
  • Azure File share volume mounts are limited to CIFS support.

Note

Mounting an Azure Files share to a container instance is similar to a Docker bind mount. If you mount a share into a container directory in which files or directories exist, the mount obscures files or directories, making them inaccessible while the container runs.

Important

If you are deploying container groups into an Azure Virtual Network, you must add a service endpoint to your Azure Storage Account.

Create an Azure file share

Before using an Azure file share with Azure Container Instances, you must create it. Run the following script to create a storage account to host the file share, and the share itself. The storage account name must be globally unique, so the script adds a random value to the base string.

# Change these four parameters as needed
ACI_PERS_RESOURCE_GROUP=myResourceGroup
ACI_PERS_STORAGE_ACCOUNT_NAME=mystorageaccount$RANDOM
ACI_PERS_LOCATION=eastus
ACI_PERS_SHARE_NAME=acishare

# Create the storage account with the parameters
az storage account create \
    --resource-group $ACI_PERS_RESOURCE_GROUP \
    --name $ACI_PERS_STORAGE_ACCOUNT_NAME \
    --location $ACI_PERS_LOCATION \
    --sku Standard_LRS

# Create the file share
az storage share create \
  --name $ACI_PERS_SHARE_NAME \
  --account-name $ACI_PERS_STORAGE_ACCOUNT_NAME

Get storage credentials

To mount an Azure file share as a volume in Azure Container Instances, you need three values: the storage account name, the share name, and the storage access key.

  • Storage account name - If you used the preceding script, the storage account name was stored in the $ACI_PERS_STORAGE_ACCOUNT_NAME variable. To see the account name, type:

    echo $ACI_PERS_STORAGE_ACCOUNT_NAME

  • Share name - This value is already known (defined as acishare in the preceding script)

  • Storage account key - This value can be found using the following command:

    STORAGE_KEY=$(az storage account keys list --resource-group $ACI_PERS_RESOURCE_GROUP --account-name $ACI_PERS_STORAGE_ACCOUNT_NAME --query "[0].value" --output tsv)
echo $STORAGE_KEY

Deploy container and mount volume - CLI

To mount an Azure file share as a volume in a container by using the Azure CLI, specify the share and volume mount point when you create the container with az container create. If you followed the previous steps, you can mount the share you created earlier by using the following command to create a container:

az container create \
    --resource-group $ACI_PERS_RESOURCE_GROUP \
    --name hellofiles \
    --image mcr.microsoft.com/azuredocs/aci-hellofiles \
    --dns-name-label aci-demo \
    --ports 80 \
    --azure-file-volume-account-name $ACI_PERS_STORAGE_ACCOUNT_NAME \
    --azure-file-volume-account-key $STORAGE_KEY \
    --azure-file-volume-share-name $ACI_PERS_SHARE_NAME \
    --azure-file-volume-mount-path /aci/logs/

The --dns-name-label value must be unique within the Azure region where you create the container instance. Update the value in the preceding command if you receive a DNS name label error message when you execute the command.

Manage files in mounted volume

Once the container starts up, you can use the simple web app deployed via the Microsoft aci-hellofiles image to create small text files in the Azure file share at the mount path you specified. Obtain the web app's fully qualified domain name (FQDN) with the az container show command:

az container show --resource-group $ACI_PERS_RESOURCE_GROUP \
  --name hellofiles --query ipAddress.fqdn --output tsv

After saving text using the app, you can use the Azure portal or a tool like the Microsoft Azure Storage Explorer to retrieve and inspect the file or files written to the file share.

Deploy container and mount volume - YAML

You can also deploy a container group and mount a volume in a container with the Azure CLI and a YAML template. Deploying by YAML template is a preferred method when deploying container groups consisting of multiple containers.

The following YAML template defines a container group with one container created with the aci-hellofiles image. The container mounts the Azure file share acishare created previously as a volume. Where indicated, enter the name and storage key for the storage account that hosts the file share.

As in the CLI example, the dnsNameLabel value must be unique within the Azure region where you create the container instance. Update the value in the YAML file if needed.

apiVersion: '2019-12-01'
location: eastus
name: file-share-demo
properties:
  containers:
  - name: hellofiles
    properties:
      environmentVariables: []
      image: mcr.microsoft.com/azuredocs/aci-hellofiles
      ports:
      - port: 80
      resources:
        requests:
          cpu: 1.0
          memoryInGB: 1.5
      volumeMounts:
      - mountPath: /aci/logs/
        name: filesharevolume
  osType: Linux
  restartPolicy: Always
  ipAddress:
    type: Public
    ports:
      - port: 80
    dnsNameLabel: aci-demo
  volumes:
  - name: filesharevolume
    azureFile:
      sharename: acishare
      storageAccountName: <Storage account name>
      storageAccountKey: <Storage account key>
tags: {}
type: Microsoft.ContainerInstance/containerGroups

To deploy with the YAML template, save the preceding YAML to a file named deploy-aci.yaml, then execute the az container create command with the --file parameter:

# Deploy with YAML template
az container create --resource-group myResourceGroup --file deploy-aci.yaml

Deploy container and mount volume - Resource Manager

In addition to CLI and YAML deployment, you can deploy a container group and mount a volume in a container using an Azure Resource Manager template.

First, populate the volumes array in the container group properties section of the template.

Then, for each container in which you'd like to mount the volume, populate the volumeMounts array in the properties section of the container definition.

The following Resource Manager template defines a container group with one container created with the aci-hellofiles image. The container mounts the Azure file share acishare created previously as a volume. Where indicated, enter the name and storage key for the storage account that hosts the file share.

As in the previous examples, the dnsNameLabel value must be unique within the Azure region where you create the container instance. Update the value in the template if needed.

{
  "$schema": "https://schema.management.azure.com/schemas/2015-01-01/deploymentTemplate.json#",
  "contentVersion": "1.0.0.0",
  "variables": {
    "container1name": "hellofiles",
    "container1image": "mcr.microsoft.com/azuredocs/aci-hellofiles"
  },
  "resources": [
    {
      "name": "file-share-demo",
      "type": "Microsoft.ContainerInstance/containerGroups",
      "apiVersion": "2019-12-01",
      "location": "[resourceGroup().location]",
      "properties": {
        "containers": [
          {
            "name": "[variables('container1name')]",
            "properties": {
              "image": "[variables('container1image')]",
              "resources": {
                "requests": {
                  "cpu": 1,
                  "memoryInGb": 1.5
                }
              },
              "ports": [
                {
                  "port": 80
                }
              ],
              "volumeMounts": [
                {
                  "name": "filesharevolume",
                  "mountPath": "/aci/logs"
                }
              ]
            }
          }
        ],
        "osType": "Linux",
        "ipAddress": {
          "type": "Public",
          "ports": [
            {
              "protocol": "tcp",
              "port": "80"
            }
          ],
          "dnsNameLabel": "aci-demo"
        },
        "volumes": [
          {
            "name": "filesharevolume",
            "azureFile": {
                "shareName": "acishare",
                "storageAccountName": "<Storage account name>",
                "storageAccountKey": "<Storage account key>"
            }
          }
        ]
      }
    }
  ]
}

To deploy with the Resource Manager template, save the preceding JSON to a file named deploy-aci.json, then execute the az deployment group create command with the --template-file parameter:

# Deploy with Resource Manager template
az deployment group create --resource-group myResourceGroup --template-file deploy-aci.json

Mount multiple volumes

To mount multiple volumes in a container instance, you must deploy using an Azure Resource Manager template, a YAML file, or another programmatic method. To use a template or YAML file, provide the share details and define the volumes by populating the volumes array in the properties section of the file.

For example, if you created two Azure Files shares named share1 and share2 in storage account myStorageAccount, the volumes array in a Resource Manager template would appear similar to the following:

"volumes": [{
  "name": "myvolume1",
  "azureFile": {
    "shareName": "share1",
    "storageAccountName": "myStorageAccount",
    "storageAccountKey": "<storage-account-key>"
  }
},
{
  "name": "myvolume2",
  "azureFile": {
    "shareName": "share2",
    "storageAccountName": "myStorageAccount",
    "storageAccountKey": "<storage-account-key>"
  }
}]

Next, for each container in the container group in which you'd like to mount the volumes, populate the volumeMounts array in the properties section of the container definition. For example, this mounts the two volumes, myvolume1 and myvolume2, previously defined:

"volumeMounts": [{
  "name": "myvolume1",
  "mountPath": "/mnt/share1/"
},
{
  "name": "myvolume2",
  "mountPath": "/mnt/share2/"
}]

Next steps

Learn how to mount other volume types in Azure Container Instances: