First, open Mattermost and open the System Console «Integration Management» section.
Then, enable Incoming Webhooks and allow integrations to override usernames and profile pictures.
Once you are done, open the «Integrations» menu. Then, add a new «Incoming Webhook».
In the form, choose the Channel in which you want iceScrum to publish content. Do not provide a username / password as content will be published as «iceScrum».
Copy the resulting Webhook URL to your clipboard.
Once you have your Mattermost Webhook URL, login as a ScrumMaster, enable the iceScrum Mattermost App and configure it in your project settings by providing the URL.
Once the integration is configured, every story creation, state change and deletion will be submitted to your Mattermost.