# Triggers

Triggers define the type of event that runs your workflow. Workflows execute on every trigger event.

For example, HTTP triggers expose a URL where you can send any HTTP requests. We'll run your workflow on each request. The Cron Scheduler trigger runs your workflow on a schedule.

Today, we support the following triggers:

In the future we plan to support triggers for SQL, AMQP, and more. If there's a trigger you'd like supported, please let us know.

# App-based Triggers

You can trigger a workflow on events from apps like Twitter, Google Calendar, and more using event sources.

When you create a workflow, choose the opton to Create Event Source in the trigger step. Select your app, and you'll see a list of available sources. For Google Calendar, for example, you can run your workflow every time a new event is added to your calendar, each time an event starts, ends, and more:

Google Calendar sources

Once you select your source, you'll be asked to connect any necessary accounts (for example, Google Calendar sources require you authorize Pipedream access to your Google account), and enter the values for any configuration settings tied to the source.

Some sources are configured to retrieve an initial set of events when they're created. Others require you to generate events in the app to trigger your workflow. If your source generates an initial set of events, you'll see them appear in the test event menu in the trigger step. Then you can select a specific test event and manually trigger your workflow with that event data.

Moreover, since event sources can produce a large stream of events, the workflow is configured to pause the stream of events from source to workflow when you first create your workflow. This way, you can author your workflow without it being triggered automatically by your source, sending test events manually during development, instead. Once you're done, you can toggle the source on in the top-right of the trigger step.

# What's the difference between an event source and a trigger?

You'll notice the docs use the terms event source and trigger interchangeably above. It's useful to clarify the distinction in the context of workflows.

Event sources run code that collects events from some app or service and emits events as the source produces them. An event source can be used to trigger any number of workflows.

For example, you might create a single source to listen for new Twitter mentions for a keyword, then trigger multiple workflows each time a new tweet is found: one to send new tweets to Slack, another to save those tweets to an Amazon S3 bucket, etc.

This model allows you to separate the data produced by a service (the event source) from the logic to process those events in different contexts (the workflow).

Moreover, you can access events emitted by sources using Pipedream's SSE and REST APIs. This allows you to access these events in your own app, outside Pipedream's platform.

# Shape of the event object

In all workflows, you have access to event data using one of two variables:

  • steps.trigger.event
  • event (shorthand reference)

The shape of the event is specific to the source. For example, RSS sources produce events with a url and title property representing the data provided by new items from a feed. Google Calendar sources produce events with a meeting title, start date, etc.

# HTTP

When you select the HTTP trigger, we create a URL endpoint specific to your workflow.

You can send any HTTP requests to this endpoint, from anywhere on the web. You can configure the endpoint as the destination URL for a webhook or send HTTP traffic from your application - we'll accept any valid HTTP request.

# Accessing HTTP request data

You can access properties of the HTTP request, like the method, payload, headers, and more, in the event object, accessible in any code or action step.

# Valid Requests

You can send a request to your endpoint using any valid HTTP method: GET, POST, HEAD, and more.

We default to generating HTTPS URLs in the UI, but will accept HTTP requests against the same endpoint URL.

You can send data to any path on this host, with any query string parameters. You can access the full URL in the event object if you'd like to write code that interprets requests with different URLs differently.

You can send data of any Media Type in the body of your request.

The primary limit we impose is on the size of the request body: we'll issue a 413 Payload Too Large status when the body exceeds our specified limit.

# How Pipedream handles JSON payloads

JSON is the main data exchange format on the web today. Pipedream optimizes for the case where you've sent JSON as the source event to a workflow.

When you send JSON in the HTTP payload, or when JSON data is sent in the payload from a webhook provider, Pipedream converts that JSON to its equivalent JavaScript object. The trigger data can be referenced using either event or the steps object.

You can confirm this JSON to JavaScript object conversion occurred by examining the event.inferred_body_type property. If this is JSON, we correctly recognized the payload as such, and converted event.body to an object accordingly.

In the Inspector, we present event.body cleanly, indenting nested properties, to make the payload easy to read. Since event.body is a JavaScript object, it's easy to reference and manipulate properties of the payload using dot-notation.

# How Pipedream handles multipart/form-data

When you send form data to Pipedream using a Content-Type of multipart/form-data, Pipedream parses the payload and converts it to a JavaScript object with a property per form field. For example, if you send a request with two fields:

curl -F 'name=Leia' -F 'title=General' https://myendpoint.m.pipedream.net

Pipedream will convert that to a JavaScript object, event.body, with the following shape:

{
  name: "Leia",
  title: "General",
}

In this case, the inferred_body_type property of the event object will be set to MULTIPART_FORM to signal that we inferred form data and applied the conversion.

# Limits

You can send any content, up to the HTTP payload size limit, as a part of the form request. The content of uploaded images or other binary files does not contribute to this limit — the contents of the file will be uploaded at a Pipedream URL you have access to within your source or workflow. See the section on Large File Support for more detail.

# Large File Support

You can upload any file to a workflow or an event source by making a multipart/form-data HTTP request with the file as one of the form parts. Pipedream saves that file to a Pipedream-owned Amazon S3 bucket, generating a signed URL that allows you to access to that file for up to 30 minutes. After 30 minutes, the signed URL will be invalidated, and the file will be deleted.

This URL is provided in the event data that triggers your workflow / source, so you can download the file using that URL within your workflow, or pass the URL on to another third-party system for it to process.

# Example: upload a file using cURL

For example, you can upload an image to a workflow using cURL:

curl -F 'image=@my_image.png' https://myendpoint.m.pipedream.net

The -F tells cURL we're sending form data, with a single "part": a field named image, with the content of the image as the value (the @ allows cURL to reference a local file).

When you send this image to a workflow, Pipedream parses the form data and converts it to a JavaScript object, event.body. Select the event from the inspector, and you'll see the image property under event.body:

Image form data

When you upload a file as a part of the form request, Pipedream saves it to a Pipedream-owned Amazon S3 bucket, generating a signed URL that allows you to access to that file for up to 30 minutes. After 30 minutes, the signed URL will be invalidated, and the file will be deleted.

Within the image property of event.body, you'll see the value of this URL in the url property, along with the filename and mimetype of the file. Within your workflow, you can download the file, or pass the URL to a third party system to handle, and more.

# Example: Download this file to the /tmp directory

This workflow downloads an image passed in the image field in the form request, saving it to the /tmp directory.

const stream = require("stream");
const { promisify } = require("util");
const fs = require("fs");
const got = require("got");

const pipeline = promisify(stream.pipeline);
await pipeline(
  got.stream(steps.trigger.event.body.image.url),
  fs.createWriteStream(`/tmp/${steps.trigger.event.body.image.filename}`)
);

# Example: Upload image to your own Amazon S3 bucket

This workflow streams the uploaded file to an Amazon S3 bucket you specify, allowing you to save the file to long-term storage.

# Limits

Since large files are uploaded using a Content-Type of multipart/form-data, the limits that apply to form data also apply here.

The content of the file itself does not contribute to the HTTP payload limit imposed for forms. You can upload files up to 5TB in size. However, files that large may trigger other Pipedream limits. Please reach out with any specific questions or issues.

# Cross-Origin HTTP Requests

We return the following headers on HTTP OPTIONS requests:

Access-Control-Allow-Origin: *
Access-Control-Allow-Methods: GET,HEAD,PUT,PATCH,POST,DELETE

Thus, your endpoint will accept cross-origin HTTP requests from any domain, using any standard HTTP method.

# HTTP Responses

# Default HTTP response

By default, when you send a valid HTTP request to your endpoint URL, you should expect to receive a 200 OK status code with the following payload:

<p><b>Success!</b></p>
<p>To customize this response, check out our docs <a href="https://docs.pipedream.com/workflows/steps/triggers/#http-responses">here</a></p>

When you're processing HTTP requests, you often don't need to issue any special response to the client. We issue this default response so you don't have to write any code to do it yourself.

# Customizing the HTTP response

If you need to issue a custom HTTP response from a workflow, you can use the $respond() function in a Code or Action step.

$respond() takes a single argument: an object with properties that specify the body, headers, and HTTP status code you'd like to respond with:

$respond({
  status: 200,
  headers: { "my-custom-header": "value" },
  body: { message: "My custom response" }, // This can be any string, object, Buffer, or Readable stream
});

The value of the body property can be either a string, object, a Buffer (binary data), or a Readable stream. Attempting to return any other data may yield an error.

In the case where you return a Readable stream:

  • You must await the $respond function (await $respond({ ... })
  • The stream must close and be finished reading within your workflow execution timeout.
  • You cannot return a Readable and use the immediate: true property of $respond.

You can Copy this example workflow and make an HTTP request to its endpoint URL to experiment with this.

# Timing of $respond() execution

You may notice some response latency calling workflows that use $respond() from your HTTP client. By default, $respond() is called at the end of your workflow, after all other code is done executing, so it may take some time to issue the response back.

If you need to issue an HTTP response in the middle of a workflow, see the section on returning a response immediately.

# Returning a response immediately

You can issue an HTTP response within a worklow, and continue the rest of the workflow execution, by setting the immediate property to true:

$respond({
  immediate: true,
  status: 200,
  headers: { "my-custom-header": "value" },
  body: { message: "My custom response" },
});

Passing immediate: true tells $respond() to issue a response back to the client at this point in the workflow. After the HTTP response has been issued, the remaining code in your workflow runs.

This can be helpful, for example, when you're building a Slack bot. When you send a message to a bot, Slack requires a 200 OK response be issued immediately, to confirm receipt:

await $respond({
  immediate: true,
  status: 200,
  body: "",
});

Once you issue the response, you'll probably want to process the message from the user and respond back with another message or data requested by the user.

Here's an example workflow that shows how to use immediate: true and run code after the HTTP response is issued.

# Errors with HTTP Responses

If you use $respond() in a workflow, you must always make sure $respond() is called in your code. If you make an HTTP request to a workflow, and run code where $respond() is not called, your endpoint URL will issue a 400 Bad Request error with the following body:

No $respond called in workflow

This might happen if:

  • You call $respond() conditionally, where it does not run under certain conditions.
  • Your workflow throws an Error before you run $respond().
  • You return data in the body property that isn't a string, object, or Buffer.

If you can't handle the 400 Bad Request error in the application calling your workflow, you can implement try / finally logic to ensure $respond() always gets called with some default message. For example:

try {
  // Your code here that might throw an exception or not run
} finally {
  $respond({
    status: 200,
    body: {
      msg: "Default response",
    },
  });
}

# Errors

Occasionally, you may encounter errors when sending requests to your endpoint:

# Request Entity Too Large

The endpoint will issue a 413 Payload Too Large status code when the body of your request exceeds 512KB.

In this case, the request will still appear in the inspector, with information on the error.

# API key does not exist

Your API key is the host part of the endpoint, e.g. the eniqtww30717 in eniqtww30717.m.pipedream.net. If you attempt to send a request to an endpoint that does not exist, we'll return a 404 Not Found error.

We'll also issue a 404 response on workflows with an HTTP trigger that have been deactivated.

# Too Many Requests

If you send too many requests to your HTTP source within a small period of time, we may issue a 429 Too Many Requests response. Review our limits to understand the conditions where you might be throttled.

You can also reach out to inquire about raising this rate limit.

If you control the application sending requests, you should implement a backoff strategy to temporarily slow the rate of events.

# Validating requests

Since you have access to the entire request object, and can issue any HTTP response from a workflow, you can implement custom logic to validate requests using any Node code.

For example, you can require requests pass a specific secret in a header. Just copy the workflow and add your secret as the value of the the Secret param. Add the rest of your code in steps below this initial one. Requests must contain the secret:

curl -H 'X-Pipedream-Secret: abc123' https://myendpoint.m.pipedream.net

Otherwise, the workflow will end early.

Since you can run any Node code in a workflow, you can implement more complex validation. For example, you could require JWT tokens and validate those tokens using the jsonwebtoken package at the start of your workflow.

# Webhook

A Webhook trigger is an alias for the HTTP trigger. They are equivalent in every way. You can trigger workflows on HTTP requests using either the HTTP or Webhook trigger.

# Cron Scheduler

Pipedream allows you to run hosted cron jobs — any code run on a schedule — for free.

We call these cron jobs "workflows". Workflows are just scripts that run on a schedule.

You can write a cron job to:

Pipedream manages the servers where these cron jobs run, so you don't have to worry about setting up a server of your own or operating some service just to run code on a schedule. You write the workflow, we take care of the rest.

# Choosing a cron trigger

To create a cron job, create a new workflow and search for the Cron Scheduler trigger:

Cron Scheduler source

By default, your cron job will be turned Off. To enable it, select either of the scheduling options:

  • Simple : run the job every N days, hours, minutes (e.g. every 1 day, every 3 hours).
  • Cron expression : schedule your job using a cron expression. For example, the expression 0 0 * * * will run the job every day at midnight. Cron expressions can be tied to any timezone.

# Testing a cron job

If you're running a cron job once a day, you probably don't want to wait until the next day's run to test your new code. You can manually run the workflow associated with a cron job at any time by pressing the Send Test Event button.

# Future executions of your cron job

You'll see the time your job is scheduled to run next under the Next Job section of the Inspector.

# Job History

You'll see the history of job executions under the Job History section of the Inspector.

Clicking on a specific job shows the execution details for that job — all the logs and observability associated with that run of the workflow.

# Trigger a notification to an external service (email, Slack, etc.)

You can send yourself a notification — for example, an email or a Slack message — at any point in a workflow by using the relevant Action or Destination.

If you'd like to email yourself when a job finishes successfully, you can use the Email Destination. You can send yourself a Slack message using the Slack Action, or trigger an HTTP request to an external service.

You can also write code to trigger any complex notification logic you'd like.

# Rate Limit

When you're testing cron jobs, you may encounter Rate Limit Exceeded errors. Cron jobs can be tested no more than twice a minute. If you encounter this error, wait one minute and try again.

# Troubleshooting your cron jobs

When you run a cron job, you may need to troubleshoot errors or other execution issues. Pipedream offers built-in, step-level logs that show you detailed execution information that should aid troubleshooting.

Any time a cron job runs, you'll see a new execution appear in the Inspector. This shows you when the cron job ran, how long it took to run, and any errors that might have occurred. Click on any of these lines in the Inspector to view the details for a given run.

Code steps show Logs below the step itself. Any time you run console.log() or other functions that print output, you should see the logs appear directly below the step where the code ran.

Actions and Destinations also show execution details relevant to the specific Action or Destination. For example, when you use the HTTP Destination to make an HTTP request, you'll see the HTTP request and response details tied to that Destination step:

# Limitations

Cron jobs can be run at most once a minute. Any cron expression that specifies a higher frequency will be rejected.

Cron jobs can run for at most 30 seconds, by default. You can raise this up to 300 seconds by setting your workflow's execution timeout. If your workflow runs longer than the configured timeout, you'll see a TIMEOUT error for that run, and will be able to review all logs up until the timeout occurred.

# Email

When you select the Email trigger, we create an email address specific to your workflow. Any email sent to this address triggers your workflow.

As soon as you send an email to the workflow-specific address, Pipedream parses its body, headers, and attachments into a JavaScript object it exposes in the steps.trigger.event variable that you can access within your workflow. This transformation can take a few seconds to perform. Once done, Pipedream will immediately trigger your workflow with the transformed payload.

Read more about the shape of the email trigger event.

# Appending metadata to the incoming email address with +data

Pipedream provides a way to append metadata to incoming emails by adding a + sign to the incoming email key, followed by any arbitrary string:

myemailaddr+test@pipedream.net

Any emails sent to your workflow-specific email address will resolve to that address, triggering your workflow, no matter the data you add after the + sign. Sending an email to both of these addresses triggers the workflow with the address myemailaddr@pipedream.net:

myemailaddr+test@pipedream.net
myemailaddr+unsubscribe@pipedream.net

This allows you implement conditional logic in your workflow based on the data in that string.

# Limitations

See the Email Trigger section of our Limits doc to learn more about the limits of the email trigger.

# SDK

You can trigger workflows using the Pipedream JavaScript and Ruby SDKs, as well.

Select the SDK trigger to generate workflow-specific code samples for sending events to your workflow using each of the SDKs.

# Don't see a trigger you need?

If you don't see a trigger you'd like us to support, please let us know.

Still have questions?

Please reach out if this doc didn't answer your question. We're happy to help!