Load Balancing and Protecting Cloud Director with Avi Networks

Overview

The Avi Vantage platform is built on software-defined principles, enabling a next generation architecture to deliver the flexibility and simplicity expected by IT and lines of business. The Avi Vantage architecture separates the data and control planes to deliver application services beyond load balancing, such as application analytics, predictive autoscaling, micro-segmentation, and self-service for app owners in both on-premises or cloud environments. The platform provides a centrally managed, dynamic pool of load balancing resources on commodity x86 servers, VMs or containers, to deliver granular services close to individual applications. This allows network services to scale near infinitely without the added complexity of managing hundreds of disparate appliances.

https://avinetworks.com/docs/18.2/architectural-overview/

Avi components

Controllers – these are the management appliances that are responsible for state data, Service Engines are deployed by the controllers. The controllers run in a management network.

Service Engines – the load balancing services run in here. These generally run in a DMZ network. Service Engines can have one or more network adaptors connected to multiple networks. At least one network with routing to the controllers, and the remaining networks as data networks.

Deployment modes

Avi can be installed in a variety of deployment types. For VMware Cloud on AWS, it is not currently possible to deploy using ‘write access’ as vCenter is locked-down in VMC and it also has a different API from vSphere 6.7 vCenter Server. You’ll also find that other tools may not work with vCenter in a VMware Cloud on AWS SDDC, such as govc.

Instead Avi needs to be deployed using ‘No Access’ mode.

You can refer to this link for instructions to deploy Avi Controllers in ‘No Access’ mode.

Since it is only possible to use ‘No Access’ mode with VMC based SDDCs, its also a requirement to deploy the service engines manually. To do this follow the guide in this link, and start at the section titled Downloading Avi Service Engine on OVA.

If you’re using Avi with on-premises deployments of vCenter, then ‘Write Mode’ can be used to automate the provisioning of service engines. Refer to this link for more information on the different modes.

Deploying Avi Controller with govc

You can deploy the Avi Controller onto non VMware Cloud on AWS vCenter servers using the govc tool. Refer to this other post on how to do so. I’ve copied the JSON for the controller.ova for your convenience below.

{
    "DiskProvisioning": "flat",
    "IPAllocationPolicy": "dhcpPolicy",
    "IPProtocol": "IPv4",
    "PropertyMapping": [
        {
            "Key": "avi.mgmt-ip.CONTROLLER",
            "Value": ""
        },
        {
            "Key": "avi.mgmt-mask.CONTROLLER",
            "Value": ""
        },
        {
            "Key": "avi.default-gw.CONTROLLER",
            "Value": ""
        },
        {
            "Key": "avi.sysadmin-public-key.CONTROLLER",
            "Value": ""
        }
    ],
    "NetworkMapping": [
        {
            "Name": "Management",
            "Network": ""
        }
    ],
    "MarkAsTemplate": false,
    "PowerOn": false,
    "InjectOvfEnv": false,
    "WaitForIP": false,
    "Name": null
}

Architecture

For a high-level architecture overview, this link provides a great starting point.

Service Engine Typical Deployment Architecture

Generally in legacy deployments, where BGP is not used. The service engines would tend to have three network interfaces. These are typically used for frontend, backend and management networks. This is typical of traditional deployments with F5 LTM for example.

For our example here, I will use three networks for the SEs as laid out below.

Network name	Gateway CIDR	Purpose
sddc-cgw-vcd-dmz1	10.104.125.1/24	Management
sddc-cgw-vcd-dmz2	10.104.126.1/24	Backend
sddc-cgw-vcd-dmz3	10.104.127.1/24	Frontend

The service engines are configured with the following details. It is important to make a note of the MAC addresses in ‘No access’ mode as you will need this information later.

Service Engine	avi-se1	avi-se2
Management	IP Address 10.104.125.11 Mac Address 00:50:56:8d:c0:2e	IP Address 10.104.125.12 Mac Address 00:50:56:8d:38:33
Backend	IP Address 10.104.126.11 Mac Address 00:50:56:8d:8e:41	IP Address 10.104.126.12 Mac Address 00:50:56:8d:53:f6
Frontend	IP Address 10.104.127.11 Mac Address 00:50:56:8d:89:b4	IP Address 10.104.127.12 Mac Address 00:50:56:8d:80:41

The Management network is used for communications between the SEs and the Avi controllers. For the port requirements, please refer to this link.

The Backend network is used for communications between the SEs and the application that is being load balanced and protected by Avi.

The Frontend network is used for upstream communications to the clients, in this case the northbound router or firewall towards the Internet.

Sample Application

Lets use VMware Cloud Director as the sample application for configuring Avi. vCD as it is more commonly named (to be renamed VMware Cloud Director), is a cloud platform which is deployed with an Internet facing portal. Due to this, it is always best to protect the portal from malicious attacks by employing a number of methods.

Some of these include, SSL termination and web application filtering. The following two documents explain this in more detail.

vCloud Director Security and VMware vCloud Director Security Hardening Guide.

The vCD application is configured as below:

	vCD Appliance 1	vCD Appliance 2
name	vcd-fe1	vcd-fe2
eth0 ip address	10.104.123.21	10.104.123.22
static route	10.104.123.1 10.104.126.0/24	10.104.123.1 10.104.126.0/24
eth1 ip address	10.104.124.21	10.104.124.22

You’ll notice that the eth0 and eth1 interfaces are connected to two different management networks 10.104.123.0/24 and 10.104.124.0/24 respectively. For vCD, it is generally good practice to separate the two interfaces into separate networks.

Network name	Gateway CIDR	Purpose
sddc-cgw-vcd-mgmt-1	10.104.123.1/24	vCD Frontend UI/API/VM Remote Console
sddc-cgw-vcd-mgmt-2	10.104.124.1/24	vCD Backend PostgreSQL, SSH etc.

For simplicity, I also deployed my Avi controllers onto the sddc-cgw-vcd-mgmt-2 network.

The diagram below summarises the above architecture for the HTTP interface for vCD. For this guide, I’ve used VMware Cloud on AWS together with Avi Networks to protect vCD running as an appliance inside the SDDC. This is not a typical deployment model as Cloud Director Service will be able to use VMware Cloud on AWS SDDC resource soon, but I wanted to showcase the possibilities and constraints when using Avi with VMC based SDDCs.

Configuring Avi for Cloud Director

After you have deployed the Avi Controllers and the Service Engines, there are few more steps needed before vCD is fully up and operational. The proceeding steps can be summarised as follows:

1. Setup networking for the service engines by assigning the right IP address to the correct MAC addresses for the data networks
2. Configure the network subnets for the service engines
3. Configure static routes for the service engines to reach vCD
4. Setup Legacy HA mode for the service engine group
5. Setup the SSL certificate for the HTTP service
6. Setup the Virtual Services for HTTP and Remote Console (VMRC)
7. Setup the server pools
8. Setup health monitors
9. Setup HTTP security policies

Map Service Engine interfaces

Using the Avi Vantage Controller, navigate to Infrastructure > Service Engine, select one of the Service Engines then click on the little pencil icon. Then map the MAC addresses to the correct IP addresses.

Configure the network subnets for the service engines

Navigate to Infrastructure > Networks and create the subnets.

Configure static routes

Navigate to Infrastructure > Routing and setup any static routes. You’ll notice from figure 2 that since the service engine has three network interfaces on different networks, we need to create a static route on the interface that does not have the default gateway. This is so the service engines knows which gateway to use to route traffic for particular traffic types. In this case, the gateway for the service engine to route the HTTP and Remote Console traffic southbound to the vCD cells.

Setup Legacy HA mode for the service engine group

Navigate to Infrastructure > Service Engine Group.

Setup the HA mode to Legacy HA. This is the simplest configuration, you can use Elastic HA if you wish.

Configure the HTTP and Remote Console Virtual Services

Navigate to Applications > Virtual Services.

Creating a Virtual Service, has a few sub tasks which include the creation of the downstream server pools and SSL certificates.

Create a new Virtual Service for the HTTP service, this is for the Cloud Director UI and API. Please use this example to create another Virtual Service for the Remote Console.

For the Remote Console service, you will need to accept TCP 443 on the load balancer but connect southbound to the Cloud Director appliances on port TCP 8443. TCP 8443 is the port that VMRC uses as it shares the same IP addresses as the HTTP service.

You may notice that the screenshot is for an already configured Virtual Service for the vCD HTTP service. The server pool and SSL certificate is already configured. Below are the screenshots for those.

Certificate Management

You may already have a signed HTTP certificate that you wish to use with the load balancer for SSL termination. To do so, you will need to use the JAVA keytool to manipulate the HTTP certificate, obtaining the private key and convert from JCEKS to PCKS12. JAVA keytool is available in the vCD appliance at /opt/vmware/vcloud-director/jre/bin/.

For detailed instructions on creating a signed certificate for vCD, please follow this guide.

Convert the keystore file certificates.ks file from JCEKS to PKCS12

keytool -importkeystore -srcstoretype JCEKS -srckeystore certificates.ks -destkeystore certificates_pkcs12.ks -deststoretype PKCS12

Export private key for the HTTP certificate from the certificates_pkcs12.ks file

keytool -importkeystore -srckeystore certificates_pkcs12.ks -srcalias http -destalias http -destkeystore httpcert.p12 -deststoretype PKCS12

Now that you have the private key for the HTTP certificate, you can go ahead and configure the HTTP certificate on the load balancer.

For the certificate file, you can either paste the text or upload the certificate file (.cer, .crt) from the certificate authority for the HTTP certificate.

For the Key (PEM) or PKCS12 file, you can use the httpcert.p12 file that you extracted from the certificates_pkcs12.ks file above.

The Key Passphrase is the password that you used to secure the httpcert.p12 file earlier.

Note that the vCD Remote Console (VMRC) must use pass-through for SSL termination, e.g., termination of the VMRC session must happen on the Cloud Director cell. Therefore, the above certificate management activities on Avi are not required for the VMRC.

Health Monitors

Navigate to Applications > Pools.

Edit the HTTP pool using the pencil icon and click on the Add Active Monitor green button.

Health monitoring of the HTTP service uses

GET /cloud/server_status HTTP/1.0

With an expected server response of

Service is up.

And a response code of 200.

The vCD Remote Console Health monitor is a lot simpler as you can see below.

Layer 7 HTTP Security

Layer 7 HTTP Security is very important and is highly recommended for any application exposed to the Internet. Layer 3 fire-walling and SSL certificates is always never enough in protecting and securing applications.

Navigate to Applications > Virtual Services.

Click on the pencil icon for the HTTP virtual service and then click on the Policies tab. Then click on the HTTP Security policy. Add a new policy with the following settings. You can read more about Layer 7 HTTP policies here.

Allowed Strings	Required by
/tenant	Tenant use
/login	Login
/network	Access to networking
/tenant-networking	Access to networking
/cloud	For SAML/SSO logins
/transfer	Uploads/Downloads of ISO and templates
/api	General API access
/cloudapi	General API access
/docs	Swagger API browser
Blocked Strings
/cloudapi/1.0.0/sessions/provider	Specifically block admin APIs from the Internet

This will drop all provider side services when accessed from the Internet. To access provider side services, such as /provider or admin APIs, use an internal connection to the Cloud Director cells.

Change Cloud Director public addresses

If not already done so, you should also change the public address settings in Cloud Director.

Testing the Cloud Director portal

Try to access https://vcloud.vmwire.com/provider

You won’t be able to access it as /provider is not on the list of allowed URI strings that we configured in the L7 HTTPS Security settings.

However, if you try to access https://vcloud.vmwire.com/tenant/vmwire, you will be able to reach the tenant portal for the organisation named VMwire.

Many thanks to Mikael Steding, our Avi Network Systems Engineer for helping me with setting this up.

Please reach out to me if you have any questions.