n8n Webhooks with Mattermost Workflow

This n8n workflow demonstrates a basic integration pattern using webhooks to trigger actions within Mattermost. It serves as a foundational example for receiving external events and posting messages to a Mattermost channel.

What it does

This workflow simplifies the process of receiving data via a webhook and subsequently sending a message to a Mattermost channel.

1. Listens for incoming data: The workflow starts by exposing a webhook URL that can receive HTTP POST requests.
2. Processes the received data: Any data sent to the webhook will be captured by the workflow.
3. Posts to Mattermost: The workflow then takes the received data and uses it to construct and send a message to a specified Mattermost channel.

Prerequisites/Requirements

To use this workflow, you will need:

• n8n Instance: A running n8n instance (self-hosted or cloud).
• Mattermost Account: Access to a Mattermost instance and a channel where you want to post messages.
• Mattermost Webhook URL: You will need to configure an incoming webhook in your Mattermost instance to get a webhook URL. This URL will be used in the "HTTP Request" node.
• Mattermost API Token: An API token for Mattermost is required for the "Mattermost" node to authenticate and post messages.

Setup/Usage

1. Import the Workflow:

   • Copy the provided JSON code.
   • In your n8n instance, go to "Workflows" and click "New".
   • Click the "Import from JSON" button (top right) and paste the JSON code.
   • Click "Import".

2. Configure the Webhook Trigger:

   • Locate the "Webhook" node.
   • The "Webhook URL" will be automatically generated once you save and activate the workflow. Copy this URL, as you will use it to send data to this workflow.

3. Configure the HTTP Request Node (Mattermost Incoming Webhook):

   • Locate the "HTTP Request" node.
   • This node is currently configured as a generic HTTP request. To post to Mattermost using an incoming webhook, you will need to:
     • Set the Method to POST.
     • Set the URL to your Mattermost Incoming Webhook URL (obtained from your Mattermost instance).
     • Set the Body Content Type to JSON.
     • In the Body Parameters, add a parameter named text (or message) and set its value using an expression to include data from the incoming webhook, e.g., ={{ $json.body.your_field_name }}.

4. Configure the Mattermost Node (Mattermost API):

   • Locate the "Mattermost" node.
   • Click on "Credential" and select an existing Mattermost API credential or create a new one.
     • For a new credential, you'll need your Mattermost API Token and the Mattermost URL.
   • Set the Operation to Post Message.
   • Specify the Channel ID or Channel Name where the message should be posted.
   • In the Message field, use an expression to include data from the incoming webhook, e.g., ={{ $json.body.some_data }}. You can also craft a custom message.

5. Activate the Workflow:

   • Once all nodes are configured, click the "Activate" toggle in the top right corner of the workflow editor.

6. Test the Workflow:

   • Send an HTTP POST request to the Webhook URL you copied in step 2. You can use tools like Postman, curl, or another n8n workflow for this.
   • Check your Mattermost channel to see the message posted by the workflow.