Azure Virtual Data Center (VDC)

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This example deploys Azure Virtual Data Center (VDC) hub-and-spoke network stacks in Azure, complete with ExpressRoute and VPN Gateways, Azure Firewall (with provision for forced tunnelling) guarding a DMZ, and Azure Bastion. In addition, as many subnets as required for shared services in the hub and application environments in the spokes may be simply specified.

In this implementation, the Azure Firewall is central. Custom routing redirects all traffic to and from hub and spokes, as well as all traffic to, within and from the DMZ, through the firewall (which scales out as a service to handle the throughput). Firewall rules are required to allow traffic through (not yet implemented). Traffic between shared services subnets in the hub and between subnets within the spokes is not redirected through the firewall, and should instead be controlled using Network Security Groups (not yet implemented).

With minimal configuration, matching stacks may be deployed in Azure paired regions, configured for Production/Disaster Recovery or High Availability (or both for different applications). Global VNet Peering between the hubs connects the separate stacks into one symmetric network.

Although the VDC pattern is in widespread use, Azure now offers a managed service intended to replace it, comprising Virtual Hub along with partner SD-WAN components, with a migration plan that illustrates the differences between the two patterns. But if you want or need to manage your own network infrastructure, VDC is still relevant.

This example uses pulumi.ComponentResource as described here which demonstrates how multiple low-level resources can be composed into a higher-level, reusable abstraction. It also demonstrates use of pulumi.StackReference as described here to relate multiple stacks. Finally, it uses Python’s ipaddress module to simplify and validate configuration of network addresses.

Prerequisites

  1. Install Pulumi
  2. Configure Pulumi for Azure
  3. Configure Pulumi for Python

Running the Example

After cloning this repo, cd into the azure-py-virtual-data-center directory and run the following commands.

  1. (recommended) Create a Python virtualenv, activate it, and install the dependent packages needed for our Pulumi program:

    $ python3 -m venv venv
    $ source venv/bin/activate
    $ pip3 install -r requirements.txt
  2. Create a new stack intended for Production (for example’s sake):

    $ pulumi stack init prod

    This will appear within your Pulumi organization under the azure-py-vdc project (as specified in Pulumi.yaml).

  3. Set the configuration variables for this stack to suit yourself, following guidance in Pulumi.yaml. This will create a new Pulumi.prod.yaml file (named after the stack) in which to store them:

    Required:

    $ pulumi config set azure:environment           public
    $ pulumi config set azure:location              australiaeast
    $ pulumi config set firewall_address_space      192.168.100.0/24
    $ pulumi config set hub_address_space           10.100.0.0/16

    Optional:

    $ pulumi config set azure_bastion               "true"
    $ pulumi config set forced_tunnel               "true"
  4. Deploy the prod stack with the pulumi up command. This may take up to an hour to provision all the Azure resources specified, including gateways, firewall and bastion hosts:

    $ pulumi up
  5. After a while, your Production stack will be ready.

    ``` Updating (prod): Type Name Status

    • pulumi:pulumi:Stack azure-py-vdc-prod created
    • ├─ vdc:network:Hub hub created
    • │ ├─ azure:network:VirtualNetwork hub-vn- created
    • │ ├─ azure:network:PublicIp hub-vpn-gw-pip- created
    • │ ├─ azure:network:PublicIp hub-fw-pip- created
    • │ ├─ azure:network:PublicIp hub-er-gw-pip- created
    • │ ├─ azure:network:Subnet hub-gw-sn created
    • │ ├─ azure:network:Subnet hub-dmz-sn created
    • │ ├─ azure:network:Subnet hub-fw-sn created
    • │ ├─ azure:network:Subnet hub-fwm-sn created
    • │ ├─ azure:network:VirtualNetworkGateway hub-vpn-gw- created
    • │ ├─ azure:network:Firewall hub-fw- created
    • │ ├─ azure:network:VirtualNetworkGateway hub-er-gw- created
    • │ ├─ azure:network:RouteTable hub-gw-rt- created
    • │ ├─ azure:network:RouteTable hub-dmz-rt- created
    • │ ├─ azure:network:RouteTable hub-ss-rt- created
    • │ ├─ azure:network:Route ss-dg-r- created
    • │ ├─ azure:network:Route ss-dmz-r- created
    • │ ├─ azure:network:Route ss-gw-r- created
    • │ ├─ azure:network:Subnet hub-domain-sn- created
    • │ ├─ azure:network:Subnet hub-files-sn- created
    • │ ├─ azure:network:SubnetRouteTableAssociation hub-dmz-sn-rta created
    • │ ├─ azure:network:Route dmz-dg-r- created
    • │ ├─ azure:network:Route dmz-dmz-r- created
    • │ ├─ azure:network:Route dmz-hub-r- created
    • │ ├─ azure:network:Route gw-gw-r- created
    • │ ├─ azure:network:SubnetRouteTableAssociation hub-gw-sn-rta created
    • │ ├─ azure:network:Route gw-dmz-r- created
    • │ ├─ azure:network:Route gw-hub-r- created
    • │ ├─ azure:network:SubnetRouteTableAssociation hub-domain-sn-rta created
    • │ └─ azure:network:SubnetRouteTableAssociation hub-files-sn-rta created
    • ├─ vdc:network:Spoke s01 created
    • │ ├─ azure:network:VirtualNetwork s01-vn- created
    • │ ├─ azure:network:VirtualNetworkPeering s01-hub-vnp- created
    • │ ├─ azure:network:VirtualNetworkPeering hub-s01-vnp- created
    • │ ├─ azure:network:Route ss-s01-r- created
    • │ ├─ azure:network:Route dmz-s01-r- created
    • │ ├─ azure:network:Route gw-s01-r- created
    • │ ├─ azure:network:RouteTable s01-rt- created
    • │ ├─ azure:network:Route s01-dg-r- created
    • │ ├─ azure:network:Route s01-dmz-r- created
    • │ ├─ azure:network:Subnet s01-web-sn- created
    • │ ├─ azure:network:Route s01-hub-r- created
    • │ ├─ azure:network:Subnet s01-db-sn- created
    • │ ├─ azure:network:Subnet s01-app-sn- created
    • │ ├─ azure:network:SubnetRouteTableAssociation s01-web-sn-rta created
    • │ ├─ azure:network:SubnetRouteTableAssociation s01-db-sn-rta created
    • │ └─ azure:network:SubnetRouteTableAssociation s01-app-sn-rta created
    • ├─ vdc:network:Spoke s02 created
    • │ ├─ azure:network:VirtualNetwork s02-vn- created
    • │ ├─ azure:network:VirtualNetworkPeering hub-s02-vnp- created
    • │ ├─ azure:network:VirtualNetworkPeering s02-hub-vnp- created
    • │ ├─ azure:network:Route ss-s02-r- created
    • │ ├─ azure:network:Route dmz-s02-r- created
    • │ ├─ azure:network:Route gw-s02-r- created
    • │ ├─ azure:network:RouteTable s02-rt- created
    • │ ├─ azure:network:Route s02-dg-r- created
    • │ ├─ azure:network:Route s02-dmz-r- created
    • │ ├─ azure:network:Route s02-hub-r- created
    • │ ├─ azure:network:Subnet s02-app-sn- created
    • │ ├─ azure:network:Subnet s02-web-sn- created
    • │ ├─ azure:network:Subnet s02-db-sn- created
    • │ ├─ azure:network:SubnetRouteTableAssociation s02-app-sn-rta created
    • │ ├─ azure:network:SubnetRouteTableAssociation s02-web-sn-rta created
    • │ └─ azure:network:SubnetRouteTableAssociation s02-db-sn-rta created
    • └─ azure:core:ResourceGroup prod-vdc-rg- created

    Outputs: dmz_ar : “192.168.100.128/25” fw_ip : “192.168.100.4” hub_as : “10.100.0.0/16” hub_id : “/subscriptions/subscription/resourceGroups/prod-vdc-rg-79a57e4b/providers/Microsoft.Network/virtualNetworks/hub-vn-46689586” hub_name: “hub-vn-46689586” s01_id : “/subscriptions/subscription/resourceGroups/prod-vdc-rg-79a57e4b/providers/Microsoft.Network/virtualNetworks/s01-vn-c2d9fe6f” s01_name: “s01-vn-c2d9fe6f” s02_id : “/subscriptions/subscription/resourceGroups/prod-vdc-rg-79a57e4b/providers/Microsoft.Network/virtualNetworks/s02-vn-61f44736” s02_name: “s02-vn-61f44736”

    Resources: + 66 created

    Duration: 31m27s

    Permalink: https://app.pulumi.com/organization/azure-py-vdc/prod/updates/1

    ```

    Feel free to modify your program, and then run pulumi up again. Pulumi automatically detects differences and makes the minimal changes necessary to achieved the desired state. If any changes to resources are made outside of Pulumi, you should first do a pulumi refresh so that Pulumi can discover the actual situation, and then pulumi up to return to desired state.

    Note that because most resources are auto-named, the trailing dashes that you see above will actually be followed by random suffixes that appear in the Outputs and in Azure.

  6. Create another new stack intended for Disaster Recovery (following the example):

    $ pulumi stack init dr

    This will also appear within your Pulumi organization under the azure-py-vdc project (as specified in Pulumi.yaml).

  7. Set the configuration variables for this stack which will be stored in a new Pulumi.dr.yaml file (change the values below to suit yourself):

    Required:

    $ pulumi config set azure:environment           public
    $ pulumi config set azure:location              australiasoutheast
    $ pulumi config set firewall_address_space      192.168.200.0/24
    $ pulumi config set hub_address_space           10.200.0.0/16

    Optional:

    $ pulumi config set azure_bastion               "true"
    $ pulumi config set forced_tunnel               "true"
  8. Deploy the dr stack with the pulumi up command. Once again, this may take up to an hour to provision all the Azure resources specified, including gateways, firewall and bastion hosts:

    $ pulumi up
  9. Once you have both Production and Disaster Recovery stacks (ideally in paired regions), you can connect their hubs using Global (between regions) VNet Peering:

    $ pulumi stack select prod
    $ pulumi config set org <your Pulumi organization>
    $ pulumi config set peer dr
    $ pulumi up
    $ pulumi stack select dr
    $ pulumi config set org <your Pulumi organization>
    $ pulumi config set peer prod
    $ pulumi up

    Note: it isn’t yet possible to discover the Pulumi organization from within the program, which is why you need to set the org configuration variable for each stack that needs to peer with another stack.

    If you later destroy a stack, you need to remove the corresponding peer variable in the other stack and run pulumi up. If you want to tear down the peerings, you should remove the peer variables in both stacks and run pulumi up:

    $ pulumi stack select prod
    $ pulumi config rm peer
    $ pulumi up
    $ pulumi stack select dr
    $ pulumi config rm peer
    $ pulumi up

    You need to remove both peerings before you can connect the hubs again.

  10. When you are finished experimenting, you can destroy all of the resources, and the stacks:

    $ pulumi stack select prod
    $ pulumi destroy
    $ pulumi stack rm
    $ pulumi stack select dr
    $ pulumi destroy
    $ pulumi stack rm