Configure VPC peering on Azure

Log in with an Azure administration account, using the Azure CLI:

az account clear
az login

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This should open a window in your browser prompting you to choose an Azure account to log in with. You need an account with at least the Application administrator role to create VPC peering. If you manage multiple Azure subscriptions, configure the Azure CLI to default to the correct subscription using the command:

az account set --subscription <subscription name or id>

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Create application object in your AD tenant, using the Azure CLI:

az ad app create --display-name "<NAME>" --available-to-other-tenants --key-type Password

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This creates an entity to your AD that can be used to log into multiple AD tenants (--available-to-other-tenants ), but only the home tenant or the tenant the app was created in has the credentials to authenticate the app. Save the appId field from the output - this is referred to as $user_app_id.

Create a service principal for your app object. Ensure that the service principal is created to the Azure subscription containing the VNet you wish to peer:

az ad sp create --id $user_app_id

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This creates a service principal to your subscription that may have permissions to peer your VNet. Save the objectId field from the output - this is referred to as $user_sp_id.

Set a password for your app object:

az ad app credential reset --id $user_app_id

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Save the password field from the output - this is referred to as $user_app_secret.

Find the ID properties of your virtual network:

az network vnet list

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Make a note of these:

• The id field, which is referred to as $user_vnet_id

• The Azure Subscription ID, which is the part after /subscriptions/ in the resource ID. This is referred to as $user_subscription_id.

• The resource group name or the resourceGroup field in the output. This is referred to as $user_resource_group.

• The Vnet name or the name field from the output as $user_vnet_name The $user_vnet_id should have the format:

  /subscriptions/$user_subscription_id/resourceGroups/$user_resource_group/providers/Microsoft.Network/virtualNetworks/$user_vnet_name.

Grant your service principal permissions to peer. The service principal that you created needs to be assigned a role that has permission for the Microsoft.Network/virtualNetworks/virtualNetworkPeerings/write action on the scope of your VNet. To limit the permissions granted to the app object and service principal, you can create a custom role with just that permission. The built-in Network Contributor role includes that permission, and can be found using az role definition list --name "Network Contributor" The id field from the output is used as $network_contributor_role_id to assign the service principal that role:

az role assignment create --role $network_contributor_role_id --assignee-object-id $user_sp_id --scope $user_vnet_id

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This allows the application object to manage the network in the --scope. Because you control the application object, it may also be given permission for the scope of an entire resource group, or the whole subscription to allow create other peerings later without assigning the role again for each VNet separately.

Create a service principal for the Managed Service for TimescaleDB application object

The Managed Service for TimescaleDB AD tenant contains an application object similar to the one you created and Timescale platform uses to create a peering from the Project VPC VNet in the Timescale subscription to the VNet in your Azure subscription. For this the Timescale app object needs a service principal in your subscription:

az ad sp create --id <ID_OF_THE_TIMESCALE_APPLICATION_OBJECT>

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Save the objectId field from the output - it is referred to as $aiven_sp_id.

If this fails with the error "When using this permission, the backing application of the service principal being created must in the local tenant" then your account does not have the correct permissions. Use an account with at least the Application administrator role assigned.

Create a custom role for the Managed Service for TimescaleDB application object

The Timescale application now has a service principal that can be given permissions. In order to target a network in your subscription with a peering and nothing else, you can create a this a custom role definition, with only a single action allowing to do that and only that:

az role definition create --role-definition '{"Name": "<name of your choosing>",
"Description": "Allows creating a peering to vnets in scope (but not from)",
"Actions": ["Microsoft.Network/virtualNetworks/peer/action"],
"AssignableScopes": ["/subscriptions/'$user_subscription_id'"]}'

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Creating a custom role must include your subscription's id in AssignableScopes . This in itself does not give permissions to your subscription - it merely restricts which scopes a role assignment can include. Save the id field from the output - this is referred to as $aiven_role_id.

Assign the custom role to the Timescale service principal to peer with your VNet, assign the role that you created in the previous step to the Timescale service principal with the scope of your VNet:

az role assignment create --role $aiven_role_id --assignee-object-id $aiven_sp_id --scope $user_vnet_id

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Get your Azure Active Directory (AD) tenant id:

az account list

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Make note of the tenantId field from the output. It is referred to as $user_tenant_id.

Create a peering connection from the Timescale Project VPC using Aiven CLI:

avn vpc peering-connection create --project-vpc-id $aiven_project_vpc_id --peer-cloud-account $user_subscription_id --peer-resource-group $user_resource_group --peer-vpc $user_vnet_name --peer-azure-app-id $user_app_id --peer-azure-tenant-id $user_tenant_id

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$aiven_project_vpc_id is the ID of the TimescaleProject VPC, and can be found using the avn vpc list command.

The Timescale platform creates a peering from the VNet in the Timescale Project VPC to the VNet in your subscription. In addition, it creates a service principal for the application object in your tenant --peer-azure-app-id $user_app_id, giving it permission to target the Timescale subscription VNet with a peering. Your AD tenant ID is also needed in order for the Timescale application object to authenticate with your tenant to give it access to the service principal that you created --peer-azure-tenant-id $user_tenant_id.

Ensure that the arguments starting with $user_ are in lower case. Azure resource names are case-agnostic, but the Aiven API currently only accepts names in lower case. If no error is shown, the peering connection is being set up by the Timescale platform.

Run the following command until the state is no longer APPROVED , but PENDING_PEER:

avn vpc peering-connection get -v --project-vpc-id $aiven_project_vpc_id --peer-cloud-account $user_subscription_id --peer-resource-group $user_resource_group --peer-vpc $user_vnet_name

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A state such as INVALID_SPECIFICATION or REJECTED_BY_PEER may be shown if the VNet specified did not exist, or the Timescale app object wasn't given permissions to peer with it. If that occurs, check your configuration and then recreate the peering connection. If everything went as expected, the state changes to PENDING_PEER within a couple of minutes showing details to set up the peering connection from your VNet to the Project VPC's VNet in the Timescale subscription.

Save the to-tenant-id field in the output. It is referred to as the aiven_tenant_id. The to-network-id field from the output is referred to as the $aiven_vnet_id.

Log out the Azure user you logged in using:

az account clear

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Log in the application object you created to your AD tenant using:

az login --service-principal -u $user_app_id -p $user_app_secret --tenant $user_tenant_id

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Log in the same application object to the Timescale AD tenant:

az login --service-principal -u $user_app_id -p $user_app_secret --tenant
$aiven_tenant_id

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Now your application object has a session with both AD tenants

Create a peering from your VNet to the VNet in the Timescale subscription:

az network vnet peering create --name <peering name of your choosing> --remote-vnet $aiven_vnet_id --vnet-name $user_vnet_name --resource-group $user_resource_group --subscription $user_subscription_id --allow-vnet-access

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If you do not specify --allow-vnet-access no traffic is allowed to flow from the peered VNet and Timescale services cannot be reached through the peering. After the peering has been created, the peering should be in the state connected.

In case you get the following error, it's possible the role assignment hasn't taken effect yet. If that is the case, try logging in again and creating the peering again after waiting a bit by repeating the commands in this step. If the error message persists, check the role assignment was correct.

The client `<random uuid>` with object id `<another random uuid>` does not have
authorization to perform action
`Microsoft.Network/virtualNetworks/virtualNetworkPeerings/write` over scope
'$user_vnet_id' If access was recently granted, refresh your credentials.

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In the Aiven CLI, check if the peering connection is ACTIVE:

avn vpc peering-connection get -v --project-vpc-id $aiven_project_vpc_id --peer-cl

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The Timescale platform polls peering connections in state PENDING_PEER regularly to see if the your subscription has created a peering connection to the Timescale Project VPC's VNet. After this is detected, the state changes from PENDING_PEER to ACTIVE. After this services in the Project VPC can be reached through the peering.