This page applies to Appian Cloud only. It may not reflect the differences with Appian Government Cloud.
This page documents how to configure an Appian Cloud to access your resources through AWS PrivateLink. For an overview of integrating with Appian Cloud using AWS PrivateLink, see AWS PrivateLink integration with Appian Cloud.
In order to integrate with PrivateLink, the Appian Cloud VPC is configured as the service consumer connecting to your resource through an interface VPC endpoint. You can connect to the following types of services:
You can create a VPC endpoint service inside your own VPC (service provider) to expose your resources. The end-to-end traffic flow is shown in the diagram below. In this example, the Appian Cloud environment forwards requests to the interface VPC endpoint over a private connection to your VPC endpoint service. In your VPC, this traffic is received by the Network Load Balancer (NLB) and routed to your service.
If your VPC endpoint service is enabled on multiple availability zones, you are required to enable Cross Zone Load Balancing on your NLB. Appian Cloud will configure the VPC interface endpoints in each of the availability zones that the endpoint service advertises.
You may also want to leverage PrivateLink to connect to supported AWS managed services. Work with your internal AWS team to configure and secure your AWS resources so that they can be accessed via the PrivateLink connection. When updating your Appian Support Case, use the managed service "service name" in your Appian Support Case notes.
Below are example AWS managed services that can be connected to Appian Cloud, however this list is not comprehensive, nor does it prescribe how you should configure your Endpoint Service. We strongly recommend that you conduct your own tests on your test and development Appian environments prior to implementing these configurations in production.
Appian Cloud supports BYOK using AWS CloudHSM. CloudHSM can be configured behind a Network Load Balancer (NLB). You can configure a VPC Endpoint Service to route to this NLB. Ensure that appropriate access to CloudHSM is properly configured.
PrivateLink can be configured to connect to your Amazon S3 Endpoint,com.amazonaws.region.s3. Ensure that access your S3 bucket is securely configured.
You can create a PrivateLink connection using the RDS Endpoint Service to perform RDS API operations.
If you need to integrate with RDS using database specific commands, you'll need to employ one of many workarounds to create a VPC endpoint service in your VPC because RDS cannot be configured behind a Network Load Balancer. There are three common options that you may attempt:
AWS PrivateLink does not support connecting one PrivateLink VPC Interface Endpoint to multiple services. If you would like to connect to multiple services, consider using an Application Load Balancer-type Target Group for Network Load Balancer. This enables you to minimize the number of Endpoint Services you'll need to connect to your Appian Cloud environments. Work with your internal AWS team to consolidate and route requests to your services.
Alternatively, configure a PrivateLink connection to each Endpoint Service. Your sites can reuse this PrivateLink connection once it's established.
You can use PrivateLink to connect your Appian Cloud High-Availability environment with your external resources. An Appian Cloud HA environment is composed of three nodes distributed across three different Availability Zones. The application server running on each node forwards requests to a single VPC interface endpoint located in the Appian Cloud VPC. From there, the traffic is routed to the customer's service in the same fashion as described in the architecture section.
The below example displays two Appian Cloud environments (Production and Development) forwarding requests to a customer's service over PrivateLink. The request originates from the Appian Cloud environment, which is routed over the interface VPC endpoint, to the customer's NLB. In this case, the customer has configured their NLB to distribute traffic between two different EC2 instances hosted in separate availability zones.
You may also utilize PrivateLink in conjunction with your own AWS Direct Connect to expose your systems to your Appian Cloud environments. Rather than forwarding traffic from the NLB directly to an AWS hosted service, you may configure your NLB with the target private IP address of your resource behind AWS Direct Connect.
Once traffic is received by the NLB, traffic can be routed through the virtual private gateway linked to your AWS Direct Connect. With this connection model, requests can be made directly to a service hosted in your private network without traversing the Internet. Note that the exact traffic flow will depend on the architecture of your network.
The prerequisites below are not necessary to connect to a supported AWS managed service. To connect with one of these, open a Support Case and specify the service name that is provided in the AWS documentation for that managed service.
|Prerequisite Steps||Description||Organizational Role|
|Create a VPC endpoint service||This service must be created in the same AWS region as your Appian Cloud environments. To create a VPC endpoint service, follow the steps here.||Your AWS Administrator|
|Allow Principals||Upon creation of a VPC endpoint service, Appian will need access to send connection requests to the endpoint service. This can be achieved by adding IAM principals to the allowed principals list. You may add an entry of `*` to allow connection requests from any principal. The connection request from Appian can then be manually approved. Alternatively, you may request Appian Support to provide a specific principal to allow.||Your AWS Administrator|
|Configure Auto Accept||Your VPC endpoint service will need to automatically accept connection requests. To set up your VPC endpoint service to automatically accept connection requests, follow the steps in the AWS documentation to Configure an endpoint service.||Your AWS Administrator|
|Create a Support Case||Open a support case with Appian Support. Include the following information:
||Your Business Relationship Owner|
Once the prerequisite steps above have been completed, Appian Support will work with you through the following configuration procedure.
We recommend testing on lower environments prior to elevating to production usage.
|Create VPC endpoint||Appian will create a VPC endpoint to connect to the VPC endpoint service you have provided.||Appian|
|Provide endpoint-specific DNS hostname||The hostname that will be used when referencing this service in your Appian Cloud environments. This configuration is required.||Appian|
|Schedule a Maintenance Window for the Affected environments||Appian Support will work with you to schedule Maintenance Windows for the affected environments once the request has been accepted. The changes will be applied during this window.||Appian|
|Update Admin Console to utilize new configurations||Admin Console updates may be required to begin integrating with the new endpoint service. You may need to make updates to pre-existing configurations using the new DNS hostnames resolving to PrivateLink. Alternatively, you may need to create new entries for brand new integrations.||Your Business Relationship Owner|
|Verify the integration works as expected||Appian Support will work with you to ensure connectivity to your resources is working as expected.||Appian / Your Business Relationship Owner|
PrivateLink does not inherently encrypt traffic. In order to enhance your application level security, some implementations may employ encryption. Depending on the implementation, these clients may perform server-side authentication (for example, HTTPS, TLS, LDAPS) in order to prove the identity of the server to the client. This type of authentication may require the caller to reference your resource using a valid DNS hostname that matches the server certificate. This should be the same DNS hostname you provided in the Support Case to associate with your VPC endpoint.
In these cases, the certificate on your resource server will need to be trusted by a public Certificate Authority. Alternatively, in some implementations, you may be able to disable server certificate validation while still encrypting traffic; however, this is not recommended as your environment would still be susceptible to a man-in-the-middle attack to circumvent the encryption.
Using the hostname provided via the Support Case, Appian will resolve any calls to the provided hostname to an Appian Cloud interface VPC endpoint ENI (Elastic Network Interface) IP Address. This will allow any requests destined to that particular hostname to resolve directly to an ENI without traversing the Internet. It is required that you enable Cross Zone Load Balancing on your NLB to ensure traffic is load balanced among your instances correctly.
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