Most automations begin with "when". When a form is filled in, when a payment comes in, when a ticket is opened. For any of that to work, something has to notice that it happened, and there are only two ways to notice. You can ask the other app every so often whether anything is new. Or the other app can tell you the moment it happens. The second way is called a webhook.
As of today, any service that can call a web address can start a Lodol workflow. Here's what a webhook is, when it beats checking on a timer, how to start a workflow from one, and how to keep it safe.
What a webhook is
A webhook is a web address that one piece of software calls to tell another that something happened, with the details attached. Your form tool calls it with the answers someone just submitted. Your payment provider calls it with the payment. The details usually arrive as named fields, such as the customer's email address, the amount and the currency, so whatever receives them can use each one.
The easiest way to picture the difference: checking on a timer is walking to the mailbox every 15 minutes to see if anything came. A webhook is the doorbell.
Checking on a timer, or being told
| Checking on a timer | A webhook | |
|---|---|---|
| How it works | Lodol asks the app what's new, again and again | The app calls Lodol when something happens |
| How soon a run starts | At the next check | Within seconds |
| What it needs | An app Lodol can read through a connection | A service that can send webhooks, and a way to tell who's calling |
| Best for | Apps that can't send webhooks | Anything that can |
For the apps Lodol already connects to, you don't have to choose. A trigger like Gmail's New email checks for new events every minute on paid plans and every 15 minutes on Free. And since this week, apps that can tell Lodol when something happens start their triggers' runs straight away, instead of at the next check. The trigger is set up the same way either way.
Webhooks matter most for everything else: a form builder, an internal tool your developers wrote, a service Lodol has no app for yet, or another automation tool you're moving away from.
Start a workflow from a webhook
The new Webhook received trigger gives a workflow a web address of its own. Setting it up takes four steps:
- Add the trigger. Start a workflow with Webhook received, and copy the address it gives you.
- Give the address to the other service. A service that sends webhooks usually has a page for them in its settings, often called Webhooks or Integrations. Paste the address there and choose which events it should send.
- Turn the workflow on. From then on, every call to the address starts one run.
- Use what arrived. The run receives what the service sent: JSON, form fields or plain text, along with the request's headers and query. Later steps read any field of it, such as the email address a form sent, with an @ reference like any other value.
The service that called is waiting for an answer, and by default it gets one as soon as the run starts. To decide the answer yourself, add a Reply to the caller step with the status code and body you choose: a thank-you for a form, a result for the tool that asked, or a refusal that tells the sender what was wrong with what it sent. The caller waits up to a minute for your reply, and the run carries on after it.
Keep it safe
A webhook address is a door into your workflow, so treat it with the same care as a password.
- Use a signing secret. Many services that send webhooks can sign each call with a secret that only you and they know. Give the trigger that secret, and Lodol checks every call's signature before it starts a run. A call with a missing or wrong signature starts nothing. Keep the secret in Secrets and Values and give the trigger its name, so the secret itself never sits in the workflow.
- Know what no secret means. Without one, anyone who has the address can start a run. That's fine for a quick test and a poor idea for a workflow that pays, posts or deletes.
- Don't trust the contents blindly. Check that the fields you need are there, with an If, before acting on them. A webhook tells you something happened; it doesn't promise the details are complete.
- Put a person in front of what matters. If a call can lead to a refund, a payment or a message to a customer, add a Request approval step so someone decides before it happens.
What happens to the data that arrives
Each call is one run, recorded step by step like any other, so you can open it and see exactly what arrived and what each step did with it. Each one counts as a run, so a service that sends a flood of events uses runs as fast as it sends them. Where you can, choose only the events you need in the other service's settings.
Services sometimes send the same event twice, for instance when they didn't hear back in time. If doing something twice would matter, such as creating an invoice, have the workflow remember the IDs it has already handled with a stored value, and skip any it has seen. And if a run fails, you get an email straight away, with the error and a link to the run.
Three more ways to start a workflow
The same release added three more triggers:
- New email (IMAP) watches a folder in any mailbox, from your company's own mail server to Fastmail or iCloud, optionally only for one sender or subject. It's on the Email (IMAP) page.
- New feed item starts a run for each new post in an RSS feed, optionally only the ones that mention a word you choose.
- Workflow failed starts a workflow whenever another one fails, with the step, the error and a link to the run. Post it in your team's channel, or open a ticket, so a failure lands where your team already works.
Webhooks in, API calls out
A webhook is another service calling Lodol. The Call an API step is the other direction: Lodol calling another service, with any method, headers and body, and its key kept in Secrets and Values. Put the two together and a service with no Lodol app at all can start a workflow and be updated by one. The docs on calling an API cover the outgoing half.
Give your next workflow a doorbell.
Start a workflow with Webhook received and paste its address into the service you want to hear from. Read more about triggers and schedules, or start free.