How to leverage HashiCorp Vault with Google Cloud Functions in TypeScript

Question

Pulumi · Accepted Answer

Leveraging HashiCorp Vault with Google Cloud Functions in a Pulumi TypeScript program involves several steps. We will create a Google Cloud Function that can access secrets from HashiCorp Vault. Before you begin, make sure you have HashiCorp Vault set up and accessible, with the necessary policies configured to allow access to the secrets you wish to use.

The following Pulumi program outlines the necessary steps:

1. Set up the Google Cloud Function with the necessary configuration.
2. Ensure the Cloud Function has the correct IAM permissions to access HashiCorp Vault.
3. Utilize the secrets management capabilities of Google Cloud Functions to securely access the secrets at runtime.

Here is a step-by-step implementation in TypeScript. This program assumes that you have already configured your Pulumi environment with the necessary Google Cloud credentials.

```typescript
import * as gcp from "@pulumi/gcp";

// This example assumes you have already set up HashiCorp Vault and have made the secrets
// available that you wish to use within your Google Cloud Function.

// Create a Google Cloud Function.
const myFunction = new gcp.cloudfunctions.Function("myFunction", {
    // Replace with the required values for your project
    runtime: "nodejs14", // The runtime of your Cloud Function
    region: "us-central1", // The region of your Cloud Function
    project: "my-project-id", // Your Google Cloud Project ID
    entryPoint: "vaultAccessFunction", // The name of the exported function in your code
    sourceArchiveBucket: myGcsBucket.name,
    sourceArchiveObject: myGcsArchive.name,
    triggerHttp: true,
    availableMemoryMb: 256, // Memory allocation for Cloud Function

// The Cloud Function will need the appropriate permissions to access HashiCorp Vault.
    // These are usually provided through IAM roles. Ensure that the service account used by the Cloud Function has the required roles.
    serviceAccountEmail: "vault-accessor@my-project-id.iam.gserviceaccount.com",

environmentVariables: {
        // These environmental variables instruct the function where to find the Vault server.
        // They should be replaced with appropriate values from your Vault setup.
        VAULT_ADDR: "https://your-vault-server-url:8200",
        VAULT_TOKEN: "your-vault-access-token",
        // Add any other environment variables needed by your function
    },

// Additional settings can be configured based on your needs.
});

// Export the URL of the funciton
export const functionUrl = myFunction.httpsTriggerUrl;

// Ensure that your function code, which is deployed to Google Cloud Functions,
// uses a client library for HashiCorp Vault to retrieve secrets and configures
// the client using the environment variables mentioned above.
```

In the above program, we create a Google Cloud Function that is configured to trigger via HTTP requests. It's assigned 256MB of memory, which is sufficient for basic functions. Ensure that you replace the placeholders with the actual values for your project, region, and function source code location.

The `serviceAccountEmail` needs to have the correct IAM permissions to access secrets in HashiCorp Vault. This is set up outside Pulumi, in the Google Cloud Console and Vault's configuration. We pass the Vault server address and access token to the function as environment variables; these will be used by your Cloud Function code to authenticate with Vault and fetch secrets.

Note that storing your Vault access token in environment variables is not necessarily best practice for production scenarios. Consider using Google Cloud's Secret Manager or other methods for secret injection that conform to your security policies.

Your actual function code (deployed on Google Cloud Functions) should include a library to interact with Vault, such as the official HashiCorp Vault Node.js client, to retrieve secrets dynamically at runtime. How this is implemented largely depends on how you manage secrets in Vault and the structure of your application.

Remember to handle your secrets carefully to avoid leaking sensitive information. Make sure that the service account used by the Cloud Function has the minimal permissions necessary to perform its tasks. Always review the [Google Cloud Function documentation](https://www.pulumi.com/registry/packages/gcp/api-docs/cloudfunctions/function/) and the [HashiCorp Vault documentation](https://www.vaultproject.io/docs) for security best practices.