Archive Response to Azure Storage

Custom Policy Example

Zuplo is extensible, so we don't have a built-in policy for Archive Response to Azure Storage, instead we have a template here that shows you how you can use your superpower (code) to achieve your goals. To learn more about custom policies see the documentation.

In this example shows how you can archive the body of outgoing responses to Azure Blob Storage. This can be useful for auditing, logging, or archival scenarios.

Example Custom Policy

The code below is an example of how this custom policy module could be implemented.

modules/archive-response-azure-storage-outbound.ts

import { HttpProblems, ZuploContext, ZuploRequest } from "@zuplo/runtime";

interface PolicyOptions {
  blobContainerPath: string;
  blobCreateSas: string;
}

export default async function (
  response: Response,
  request: ZuploRequest,
  context: ZuploContext,
  options: PolicyOptions,
) {
  // NOTE: policy options should be validated, but to keep the sample short,
  // we are skipping that here.

  // because we will read the body, we need to
  // create a clone of this response first, otherwise
  // there may be two attempts to read the body
  // causing a runtime error
  const clone = response.clone();

  // In this example we assume the body could be text, but you could also
  // response the blob() to handle binary data types like images.
  //
  // This example loads the entire body into memory. This is fine for
  // small payloads, but if you have a large payload you should instead
  // save the body via streaming.
  const body = await clone.text();

  // let's generate a unique blob name based on the date and requestId
  const blobName = `${Date.now()}-${context.requestId}.req.txt`;

  const url = `${options.blobContainerPath}/${blobName}?${options.blobCreateSas}`;

  const result = await fetch(url, {
    method: "PUT",
    body: body,
    headers: {
      "x-ms-blob-type": "BlockBlob",
    },
  });

  if (result.status > 201) {
    const text = await result.text();
    context.log.error("Error saving file to storage", text);
    return HttpProblems.internalServerError(request, context, {
      detail: text,
    });
  }

  // Continue the response
  return response;
}

Configuration

The example below shows how to configure a custom code policy in the 'policies.json' document that utilizes the above example policy code.

config/policies.json

{
  "name": "my-archive-response-azure-storage-outbound-policy",
  "policyType": "archive-response-azure-storage-outbound",
  "handler": {
    "export": "default",
    "module": "$import(./modules/YOUR_MODULE)",
    "options": {
      "blobCreateSas": "$env(BLOB_CREATE_SAS)",
      "blobContainerPath": "$env(BLOB_CONTAINER_PATH)"
    }
  }
}

• name the name of your policy instance. This is used as a reference in your routes.
• policyType the identifier of the policy. This is used by the Zuplo UI. Value should be archive-response-azure-storage-outbound.
• handler/export The name of the exported type. Value should be default.
• handler/module the module containing the policy. Value should be $import(./modules/YOUR_MODULE).
• handler/options The options for this policy:
  • blobCreateSas

    The Azure shared access token with permission to write to the bucket

  • blobContainerPath

    The path to the Azure blob container

Using the Policy

In order to use this policy, you'll need to setup Azure storage. You'll find instructions on how to do that below.

Setup Azure

First, let's set up Azure. You'll need a container in Azure storage (docs). Once you have your container you'll need the URL - you can get it on the properties tab of your container as shown below.

Note - this sample is available as a Zup It on GitHub - just click ZupIt! to deploy to your Zuplo account: https://github.com/zuplo/samples-req-archive-filestorage

This URL will be the blobPath in our policy options.

Next, we'll need a SAS (Shared Access Secret) to authenticate with Azure. You can generate one of these on the Shared access tokens tab.

Note, you should minimize the permissions - and select only the Create permission. Choose a sensible start and expiration time for your token. Note, we do not recommend restricting IP addresses because Zuplo runs at the edge in over 200 data-centers world-wide.

Then generate your SAS token - copy the token (not the URL) to the clipboard and enter it into a new environment variable in your zup called BLOB_CREATE_SAS. You'll need another environment variable called BLOB_CONTAINER_PATH.

Read more about how policies work