The HTTP action performs HTTP requests. It is commonly used to invoke third-party APIs.

All HTTP methods are supported; the results of HTTP requests may be reused by a task via mechanic/actions/perform.

Options

Request format

The HTTP action has intelligently varying behavior, based on the presence and value of the Content-Type header, and the data type of the body option.

JSON

If the Content-Type header is unspecified or set to application/json, and if the body option is set to a JSON object or array, the request body will be automatically serialized to a JSON string, and the request will contain a Content-Type header set to application/json.

Form-encoded data

If the files option is given, its contents will be evaluated for file generators, and the results will be used to construct a multipart/form-data upload request, combining generated files with any key-value pairs found in the body option.

{% action "http" %}
  {
    "method": "post",
    "url": "https://postman-echo.com/post",
    "body": {
      "hello": "world"
    },
    "files": {
      "robots.txt": {
        "url": "https://www.shopify.com/robots.txt"
      }
    }
  }
{% endaction %}

If the files option is not given, and if the Content-Type header is set to application/x-www-form-urlencoded, and if the body option is set to a JSON object or array, the request body will be serialized to a form-encoded string.

Basic authentication

To authenticate a request using the Authorization header and the "Basic" authentication type, use something like this:

{% assign username = "guest" %}
{% assign password = "guest" %}
{% assign authorization_header = username | append: ":" | append: password | base64 | prepend: "Basic " %}
​
{% action "http" %}
  {
    "method": "get",
    "url": "https://jigsaw.w3.org/HTTP/Basic/",
    "headers": {
      "Authorization": {{ authorization_header | json }}
    }
  }
{% endaction %}

Result

This action returns an object containing the following keys:

Response headers

Because HTTP allows for the same header name to be present multiple times, this action's result specifies an array for each response header – even if the header was only present once.

To retrieve a specific header in a task responding to mechanic/actions/perform, use something like this:

{% log response_type_header: action.run.result.headers['content-type'][0] %}

Response body

If the response contained a Content-Type header set to application/json, the body result value will be the result of parsing the response body for JSON.

For all other cases, the body result value will be an UTF8 string, regardless of the response body's original encoding. To access the response body in its original encoding, use the body_base64 result value, passing it through the decode_base64 Liquid filter if necessary.

Handling errors

By default, this action will consider any valid HTTP response to be a success, regardless of its response code.

However, because 5xx responses should often be considered a retryable error, this action supports the error_on_5xx option. When set to true, this action will interpret any 5xx responses as an action error.

As with all runs, HTTP action errors are subject to Mechanic's retry policy.

Example

This task prompts the user for text input, and submits it to a public API that returns everything submitted to it. The task then re-invokes itself, using the Echo action to display the response status, content type, and body.

mechanic/user/text
mechanic/actions/perform

{% if event.topic == "mechanic/user/text" %}
  {% action "http" %}
    {
      "method": "post",
      "url": "https://postman-echo.com/post",
      "body": {{ event.data | json }}
    }
  {% endaction %}
{% else %}
  {% action "echo",
    response_status: action.run.result.status,
    response_content_type: action.run.result.headers['content-type'][0],
    response_body: action.run.result.body %}
{% endif %}