Functions: how to access request info / return other response types

Posted on May 24, 2022

Unfortunately the functions docs are very, very superficial and neither contain any information on how to access the incoming request (e.g. HTTP headers, source IP, etc.) nor on how to return anything else than text responses.

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Rodric Rabbah

May 24, 2022

Thanks for the feedback. Here are some examples in Node.js to get you started. If you prefer other languages let us know but it’s the same model

function to perform an HTTP redirect

function main() {
  return {
    headers: { location: 'https://example.com' },
    statusCode: 302
  }
}

set a cookie and return some html

function main() {
  return {
    headers: {
      'Set-Cookie': 'UserID=Jane; Max-Age=3600; Version=',
      'Content-Type': 'text/html'
    },
    statusCode: 200,
    body: '<html><body><h3>hello</h3></body></html>' }
}

return image/png (or other binary content, must be base64 encode

function main() {
    let png = <base 64 encoded string>
    return { headers: { 'Content-Type': 'image/png' },
             statusCode: 200,
             body: png };
}

return json (default response)

function main(params) {
    return {
        statusCode: 200,
        headers: { 'Content-Type': 'application/json' },
        body: params
    };
}

The statusCode is optional and defaults to 200 OK. The headers are also optional. The body is required for a valid response. (This is the same as AWS Lambda.)

Rodric Rabbah

May 24, 2022

There are several properties available in the application’s context called __ow_headers, __ow_path, __ow_method which provide additional information about the calling context. These are available as arguments to the function. The first is the request headers, the second is the path segment (after your function name), and the last is the HTTP verb used to invoke the function. In addition the values __ow_query and __ow_body may be present (the latter base64 encoded) for binary and non-JSON input types. Here is an example JavaScript/Typescript repo that demonstrates how to use these.