Outgoing Webhooks¶

Enabling Outgoing Webhooks¶

Outgoing webhooks are off by default, and can be enabled by the system administrator. If you are the system administrator you can enable them by doing the following:

1. Login to your Mattermost team account that has the system administrator role.
2. Enable outgoing webhooks from System Console > Integrations > Webhooks and Commands.
3. (Optional) Configure the Enable Overriding Usernames from Webhooks and Slash Commands option to allow external applications to post messages under any name. If not enabled, the username of the creator of the webhook URL is used to post messages.
4. (Optional) Configure the Enable Overriding Icon from Webhooks and Slash Commands option to allow external applciations to change the icon of the account posting messages. If not enabled, the icon of the creator of the webhook URL is used to post messages.
5. (Optional) Configure the Enable Integrations for Admin Only option to allow only system and team admins to create outgoing webhooks

Set Up an Outgoing Webhook¶

Once outgoing webhooks are enabled, you will be able to set one up through the Mattermost UI. You will need to know the following

1. The channel you want to listen to post events from (you can leave the channel field blank if you would like to set up the webhook for all channels)
2. The trigger words (if any) that will trigger a post event if they are the first word of the post
3. The URL you want Mattermost to report the events to

Once you have those, you can follow these steps to set up your webhook:

1. Login to your Mattermost team site and go to Main Menu > Integrations > Outgoing Webhooks
2. Click Add outgoing webhook, and select your options
3. Select a channel from the Channel dropdown to only report events from a certain channel (optional if Trigger Words selected)
4. Enter comma separated words into Trigger Words to only report events from posts that start with one of those words (optional if Channel selected)
5. Enter new line separated URLs that the post events will be sent too
6. Choose when to trigger the outgoing webhook; if the first word of a message matches a Trigger Word exactly, or if the first word of a message starts with a Trigger Word.
7. Click Add to add your webhook to the system
8. Your new outgoing webhook will be displayed with a Token that any external application that wants to listen to the webhook should ask for in its instructions

Creating Integrations using Outgoing Webhooks¶

If you’d like to build your own integration that uses outgoing webhooks, you can follow these general guidelines:

1. In the programming language of your choice, write your integration to perform what you had in mind
2. Your integration should have a function for receiving HTTP POSTs from Mattermost that look like this example:

  Content-Length: 244
  User-Agent: Go 1.1 package http
  Host: localhost:5000
  Accept: application/json
  Content-Type: application/x-www-form-urlencoded

  channel_id=hawos4dqtby53pd64o4a4cmeoo&
  channel_name=town-square&
  team_domain=someteam&
  team_id=kwoknj9nwpypzgzy78wkw516qe&
  post_id=axdygg1957njfe5pu38saikdho&
  text=some+text+here&
  timestamp=1445532266&
  token=zmigewsanbbsdf59xnmduzypjc&
  trigger_word=some&
  user_id=rnina9994bde8mua79zqcg5hmo&
  user_name=somename

1. Your integration must have a configurable MATTERMOST_TOKEN variable that is the Token given to you when you set up the outgoing webhook in Mattermost as decribed in the previous section Set Up an Outgoing Webhook. This configurable MATTERMOST_TOKEN must match the token in the request body so your application can be sure the request came from Mattermost
2. If you want your integration to post a message back to the same channel, it can respond to the HTTP POST request from Mattermost with a JSON response body similar to this example:

{
  "text": "This is some response text."
}

1. Set up your integration running on Heroku, an AWS server or a server of your own to start getting real time post events from Mattermost channels

Additional Notes:

1. With Enable Overriding of Usernames from Webhooks turned on, you can also override the username the message posts as by providing a username parameter in your JSON payload. For example, you might want your message looking like it came from a robot so you can use the JSON response {"username": "robot", "text": "Hello, this is some text."} to change the username of the post to robot. Note, to combat any malicious users from trying to use this to perform phishing attacks a BOT indicator appears next to posts coming from webhooks
2. With Enable Overriding of Icon from Webhooks turned on, you can similarly change the icon the message posts with by providing a link to an image in the icon_url parameter of your JSON response. For example, {"icon_url": "http://somewebsite.com/somecoolimage.jpg", "text": "Hello, this is some text."} will post using whatever image is located at http://somewebsite.com/somecoolimage.jpg as the icon for the post
3. Also, as mentioned previously, markdown can be used to create richly formatted payloads, for example: payload={"text": "# A Header\nThe _text_ below **the** header."} creates a messages with a header, a carriage return, italicized text for “text” and bold text for “the”
4. Including @username in the JSON payload will trigger a mention notification for the person with the specified username. Channels can be mentioned by including @channel or <!channel>. For example: payload={"text": "<!channel> this is a notification""} would create a message that mentions @channel
5. Just like regular posts, the text will be limited to 4000 characters at maximum

Slack Compatibility¶

As mentioned above, Mattermost makes it easy to take integrations written for Slack’s proprietary JSON payload format and repurpose them to become Mattermost integrations. The following automatic translations are supported:

1. The HTTP POST request body is formatted the same as Slack’s, which means your Slack integration’s receiving function should not need to change at all to be compatible with Mattermost
2. JSON responses designed for Slack using <> to note the need to hyperlink a URL, such as {"text": "<http://www.mattermost.com/>"}, are translated to the equivalent markdown in Mattermost and rendered the same as you would see in Slack
3. Similiarly, responses designed for Slack using | within a <> to define linked text, such as {"text": "Click <http://www.mattermost.com/|here> for a link."}, are also translated to the equivalent markdown in Mattermost and rendered the same as you would see in Slack

To see samples and community contributions, please visit http://mattermost.org/webhooks.