zulip/templates/zerver/api/incoming-webhooks-overview.md

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# Incoming webhook integrations
An incoming webhook allows a third-party service to push data to Zulip when
something happens. There's several ways to do an incoming webhook in
Zulip:
* Use our [REST API](/api/rest) endpoint for [sending
messages](/api/send-message). This works great for internal tools
or cases where the third-party tool wants to control the formatting
of the messages in Zulip.
* Use one of our supported [integration
frameworks](/integrations/doc/meta-integration), such as the
[Slack-compatible incoming webhook](/integrations/doc/slack_incoming),
[Zapier integration](/integrations/docs/zapier), or
[IFTTT integration](/integrations/doc/ifttt).
* Adding an incoming webhook integration (detailed on this page),
where all the logic for formatting the Zulip messages lives in the
Zulip server. This is how most of [Zulip's official
integrations](/integrations) work, because they enable Zulip to
support third-party services that just have an "outgoing webhook"
feature (without the third party needing to do any work specific to
Zulip).
In an incoming webhook integration, the third-party service's
"outgoing webhook" feature sends an `HTTP POST`s to a special URL when
it has something for you, and then the Zulip "incoming webhook"
integration handles that incoming data to format and send a message in
Zulip.
New official Zulip webhook integrations can take just a few hours to
write, including tests and documentation, if you use the right
process.
## Quick guide
* Set up the
[Zulip development environment](https://zulip.readthedocs.io/en/latest/development/overview.html).
* Use <https://webhook.site/> or a similar site to capture an example
webhook payload from the third-party service. Create a
`zerver/webhooks/<mywebhook>/fixtures/` directory, and add the captured
payload as a test fixture.
* Create an `Integration` object, and add it to `WEBHOOK_INTEGRATIONS` in
`zerver/lib/integrations.py`. Search for `webhook` in that file to find an
existing one to copy.
* Write a draft webhook handler under `zerver/webhooks/`. There are a lot of
examples in that directory that you can copy. We recommend templating off
a short one, like `stash` or `zendesk`.
* Add a test for your fixture at `zerver/webhooks/<mywebhook>/tests.py`.
Run the tests for your integration like this:
```
tools/test-backend zerver/webhooks/<mywebhook>/
```
Iterate on debugging the test and webhooks handler until it all
works.
* Capture payloads for the other common types of `POST`s the third-party
service will make, and add tests for them; usually this part of the
process is pretty fast.
* Document the integration (required for getting it merged into Zulip). You
can template off an existing guide, like
[this one](https://raw.githubusercontent.com/zulip/zulip/master/zerver/webhooks/github/doc.md).
This should not take more than 15 minutes, even if you don't speak English
as a first language (we'll clean up the text before merging).
## Hello world walkthrough
Check out the [detailed walkthrough](incoming-webhooks-walkthrough) for step-by-step
instructions.
## Checklist
### Files that need to be created
Select a name for your incoming webhook and use it consistently. The examples
below are for a webhook named `MyWebHook`.
* `zerver/webhooks/mywebhook/__init__.py`: Empty file that is an obligatory
part of every python package. Remember to `git add` it.
* `zerver/webhooks/mywebhook/view.py`: The main webhook integration function
as well as any needed helper functions.
* `zerver/webhooks/mywebhook/fixtures/messagetype.json`: Sample json payload data
used by tests. Add one fixture file per type of message supported by your
integration.
* `zerver/webhooks/mywebhook/tests.py`: Tests for your webbook.
* `zerver/webhooks/mywebhook/doc.html`: End-user documentation explaining
how to add the integration.
* `static/images/integrations/logos/mywebhook.svg`: A square logo for the
platform/server/product you are integrating. Used on the documentation
pages as well as the sender's avatar for messages sent by the integration.
* `static/images/integrations/mywebbook/001.svg`: A screenshot of a message
sent by the integration, used on the documentation page.
### Files that need to be updated
* `zerver/lib/integrations.py`: Add your integration to
`WEBHOOK_INTEGRATIONS`. This will automatically register a
URL for the incoming webhook of the form `api/v1/external/mywebhook` and
associate it with the function called `api_mywebhook_webhook` in
`zerver/webhooks/mywebhook/view.py`.
## General advice
* Consider using our Zulip markup to make the output from your
integration especially attractive or useful (e.g. emoji, markdown
emphasis or @-mentions).
* Use topics effectively to ensure sequential messages about the same
thing are threaded together; this makes for much better consumption
by users. E.g. for a bug tracker integration, put the bug number in
the topic for all messages; for an integration like Nagios, put the
service in the topic.
* Integrations that don't match a team's workflow can often be
uselessly spammy. Give careful thought to providing options for
triggering Zulip messages only for certain message types, certain
projects, or sending different messages to different streams/topics,
to make it easy for teams to configure the integration to support
their workflow.
* Consistently capitalize the name of the integration in the
documentation and the Client name the way the vendor does. It's OK
to use all-lower-case in the implementation.
* Sometimes it can be helpful to contact the vendor if it appears they
don't have an API or webhook we can use; sometimes the right API
is just not properly documented.
* A helpful tool for testing your integration is
[UltraHook](http://www.ultrahook.com/), which allows you to receive webhook
calls via your local Zulip development environment. This enables you to do end-to-end
testing with live data from the service you're integrating and can help you
spot why something isn't working or if the service is using custom HTTP
headers.