Slack and Mattermost¶

Two integrations, each optional:

• Channel notifications — a project posts what happens (new issues, status changes, comments, sprints, releases, pull requests, failed pipelines) into Slack or Mattermost channels, through each channel's incoming webhook. Automation rules can post too.
• The /wfm command — look up an issue or run a search from chat.

Channel notifications¶

1. Create an incoming webhook for the channel:
2. Slack: create (or reuse) a Slack app → Incoming Webhooks → Add New Webhook to Workspace, pick the channel. The URL looks like https://hooks.slack.com/services/….
3. Mattermost: Integrations → Incoming Webhooks → Add, pick the channel. The URL looks like https://mattermost.example.com/hooks/….
4. In Workflow: Project settings → Chat → Add channel. Choose Slack or Mattermost, paste the URL, give it a name people recognise (#team-payments), and pick the events:

Everything also covers event types added in later versions. An optional query filter limits issue events to matching issues, e.g. type = Bug AND priority >= High for an on-call channel; it does not apply to sprint and release events, nor to messages from automation rules, and currentUser() matches nobody here. 3. Send test posts a test message; the channel's delivery log shows each message's status.

Messages use Slack Block Kit and Mattermost attachments, link to the issue, and are coloured by status category. The webhook URL is a credential: it is stored encrypted and never shown again (the list shows only its host and last characters; leave the field empty when editing to keep it). Deliveries are queued after the change commits; network errors, 5xx and 429 answers are retried with backoff, while other answers (a deleted channel, a revoked webhook) are recorded as failed. Pause a channel to stop messages without losing its settings.

Automation: the chat action posts a message of your own to one of the project's channels, with the usual templates — e.g. when an issue enters a done status, post "🎉 {{issue.key}} {{issue.summary}} is done" to #releases (a template in the gallery). Removing a channel pauses the rules that post to it. See automation.md.

Self-hosted Mattermost on a private network¶

Outbound calls refuse private addresses (SSRF protection). Allow your Mattermost host by name — only that host may resolve to a private address:

WFM_OUTBOUND_ALLOWED_HOSTS=mattermost.corp.example        # or .corp.example for a whole domain

In Kubernetes, worker egress allows port 443 by default; if Mattermost listens on another port (8065), add a networkPolicy.egress.extraRules entry for it.

The /wfm command¶

/wfm PLAT-12                                   show an issue (status, assignee, type, priority)
/wfm search assignee = "ada@example.com" AND statusCategory != Done
/wfm help

Answers are only visible to the person who asked. Commands are read-only and only see open projects, because a chat workspace can include guests without accounts here; set WFM_CHAT_COMMAND_PROJECTS=PLAT,OPS to choose the projects explicitly (private projects only appear when listed).

Slack: in your Slack app → Slash Commands → Create New Command: command /wfm, request URL <WFM_HOOKS_PUBLIC_URL>/hooks/chat/slack. Copy Signing Secret from Basic Information into WFM_SLACK_SIGNING_SECRET. Requests are verified with Slack's signature and rejected when older than five minutes.

Mattermost: Integrations → Slash Commands → Add: trigger word wfm, request URL <WFM_HOOKS_PUBLIC_URL>/hooks/chat/mattermost, method POST. Put the generated token in WFM_MATTERMOST_COMMAND_TOKENS (comma-separated if you have several teams).

Without the secret or token, the endpoint answers 404.