#OpenWhisk - Web Actions

Functions can be turned into "web actions" which return HTTP content without use of an API Gateway. This feature is enabled by setting an annotation (web-export) in the configuration file.

    handler: index.main
      web-export: true

Functions with this annotation can be invoked through a URL template with the following parameters.

  • APIHOST - platform endpoint e.g. openwhisk.ng.bluemix.net.
  • USER_NAMESPACE - this must be an explicit namespace and cannot use the default namespace (_).
  • PACKAGE - action package or default.
  • ACTION_NAME - default form ${servicename}-${space}-${name}.
  • TYPE - .json, .html, .text or .http.

Return values from the function are used to construct the HTTP response. The following parameters are supported.

  1. headers: a JSON object where the keys are header-names and the values are string values for those headers (default is no headers).
  2. code: a valid HTTP status code (default is 200 OK).
  3. body: a string which is either plain text or a base64 encoded string (for binary data).

Here is an example of returning HTML content:

function main(args) {
  var msg = 'you didn't tell me who you are.';
  if (args.name) {
    msg = `hello ${args.name}!`;
  return { body: `<html><body><h3><center>${msg}</center></h3></body></html>` };

Here is an example of returning binary data:

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

Functions can access request parameters using the following environment variables.

  1. __ow_method - HTTP method of the request.
  2. __ow_headers - HTTP request headers.
  3. __ow_path - Unmatched URL path of the request.
  4. __ow_body - Body entity from request.
  5. __ow_query - Query parameters from the request.

Full details on this feature are available in this here.

Have questions?

Head over to the forums to search for your questions and issues or post a new one.