HTTP

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

To use the response from an HTTP action, add a task subscription to mechanic/actions/perform.

When developing task code, verify your HTTP action's behavior with webhook.site (making sure not to share sensitive information with this service).

Options

Option	Type	Notes
method	String, required	Must be one of "options", "head", "get", "post", "put", "patch", or "delete"
url	String, required	Must start with https:// or http://
body	String, required for non-GET requests	Format varies, see below
files	Hash, optional	May be set to a JSON object, mapping filenames to file generators
headers	Hash, optional	May be set to a JSON object, mapping header names to header values
follow_redirects	Boolean, optional	Defaults to true, may be set to false; controls whether or not 3xx responses with Location headers are automatically followed to their destination
proxy	String, optional	May be a proxy URI string beginning with https://, http://, or socks5://; see "Using a proxy" below
verify	Boolean, optional	May be set to false to disable SSL certificate verification
error_on_5xx	Boolean, optional	May be set to true to have 5xx HTTP response codes be considered action errors

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 %}

Using a proxy

The HTTP action supports HTTPS, HTTP, and SOCKS5 proxy connections via the "proxy" option, set to a URI string beginning with https://, http://, or socks5://. When configured, Mechanic will open a connection to your proxy server, and pass your request through that connection.

Example HTTP action using a proxy

{% action "http" %}
  {
    "method": "get",
    "url": "https://api.ipify.org?format=json",
    "proxy": "socks5://user:[email protected]:port"
  }
{% endaction %}

We recommend using an HTTPS proxy server (rather than HTTP or SOCKS5) for a secure connection between Mechanic and your proxy. QuotaGuard Shield is a good option for this kind of service.

Mechanic does not use static IP addresses for outbound requests. Using a connection proxy for your HTTP actions can allow you to control the client IP address of your API requests, for API vendors that require fixed IPs.

Result

In Mechanic, actions are performed after their originating task run concludes. Actions are not performed inline during the task's Liquid rendering.

To inspect and respond to the results of an HTTP action, add a task subscription to mechanic/actions/perform, allowing the action to re-invoke the task with the action result data.

Learn more: Responding to action results

An HTTP action returns an object containing the following keys:

File property	Description
status	An integer, specifying the response code
headers	An object containing response headers, where each key is a string and each value is an array of values found for that header
body	The interpreted value of the response body; see below
body_base64	The original response body, encoded using base64

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.

Subscriptions

mechanic/user/text
mechanic/actions/perform

Code

{% 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 %}