Slack from self-hosted Overcut

Use this path when you run Overcut on your own infrastructure. A Slack app has a single, fixed set of URLs - its OAuth redirect, event delivery, and slash-command endpoints are registered on the app itself - and the managed Overcut Cloud Slack app points at Overcut Cloud. Your deployment therefore uses a Slack app that you create and own, pointing at your own domain. All tokens and events stay between your Slack workspace and your deployment; nothing goes through Overcut Cloud.

On Overcut Cloud, use the managed Overcut Slack app instead - see Connect to Slack. No app creation or environment configuration is needed there.

Prerequisites

Permission to create apps in your Slack workspace (and, if your workspace requires it, admin approval to install them)
A running self-hosted Overcut deployment with a public HTTPS domain (https://<your-overcut-domain>) and a browser-trusted TLS certificate
Inbound reachability from Slack: Slack’s servers must be able to reach https://<your-overcut-domain>/hooks/... over port 443
The ability to set environment variables on the deployment and restart it

Slack verifies your event endpoint with a live HTTPS request and delivers all events from Slack’s cloud. A deployment behind a firewall that blocks inbound internet traffic, or one serving a self-signed certificate, cannot complete Slack setup. This is a Slack platform requirement, not an Overcut limitation.

How it works

Your Slack app is the identity Overcut uses in Slack:

OAuth connection - connecting a Slack workspace in Overcut runs the OAuth flow against your app; the granted bot token is stored by your deployment and used to read and post messages.
Events and commands - Slack delivers channel messages, mentions, and slash commands to your deployment, signed with your app’s signing secret, which Overcut verifies on every request.

Step 1: Create the Slack app

Create the app from a manifest

Go to api.slack.com/apps, click Create New App -> From a manifest, pick the Slack workspace, and paste the manifest below - replacing <your-overcut-domain> (three occurrences) with your deployment’s domain:

display_information:
  name: Overcut
  description: Run Overcut workflows from Slack via mentions and slash commands.
  background_color: "#191919"
features:
  bot_user:
    display_name: Overcut
    always_online: true
  slash_commands:
    - command: /overcut
      url: https://<your-overcut-domain>/hooks/slack/slash-command
      description: Trigger an Overcut workflow.
      usage_hint: "<command> [args]"
      should_escape: false
oauth_config:
  redirect_urls:
    - https://<your-overcut-domain>/slack-auth-app/callback
  scopes:
    bot:
      - commands
      - app_mentions:read
      - channels:read
      - groups:read
      - channels:join
      - channels:history
      - groups:history
      - team:read
      - chat:write
      - reactions:write
settings:
  event_subscriptions:
    request_url: https://<your-overcut-domain>/hooks/slack/events
    bot_events:
      - app_mention
      - message.channels
      - message.groups
  org_deploy_enabled: false
  socket_mode_enabled: false
  token_rotation_enabled: false

Review the summary and click Create. Slack may warn that the event request URL is not yet verified - that is expected; you verify it in Step 2 after the deployment knows the signing secret.

Collect the credentials

On the app’s Basic Information page, under App Credentials, collect:

App ID
Client ID
Client Secret
Signing Secret

Step 2: Configure the deployment

Set these environment variables on your deployment:

Variable	Value
`SLACK_INTEGRATION_ENABLED`	`true`
`SLACK_APP_ID`	The App ID
`SLACK_CLIENT_ID`	The Client ID
`SLACK_CLIENT_SECRET`	The Client Secret
`SLACK_SIGNING_SECRET`	The Signing Secret
`SLACK_REDIRECT_URI`	`https://<your-overcut-domain>/slack-auth-app/callback`

The redirect URI must be byte-identical to the redirect URL registered on the Slack app (Step 1), otherwise the OAuth step fails with a redirect_uri mismatch.

Apply the configuration

Restart the deployment so the new environment variables take effect.

Verify the event endpoint

Back in the Slack app settings, open Event Subscriptions. If the request URL shows as unverified, click Retry. Slack sends a challenge to https://<your-overcut-domain>/hooks/slack/events; with the deployment running and the signing secret configured, it turns Verified.

Step 3: Connect in Overcut

Open workspace Integrations

From the workspace sidebar (no project selected), go to Integrations.

Connect Slack

In the providers list, find Slack and click connect. You are redirected to Slack to authorize your app for the Slack workspace.

Approve the OAuth scopes

Approve the requested scopes. After approval you return to Overcut and the Slack workspace appears in the connected providers list.

From here, setup continues exactly as on Overcut Cloud - register channels in a project, choose routing modes, and trigger workflows: see Connect to Slack.

Troubleshooting

Slack tile missing or disabled in Overcut: SLACK_INTEGRATION_ENABLED is not true, or the deployment was not restarted after setting it.
Event request URL verification fails: Slack cannot reach https://<your-overcut-domain>/hooks/slack/events (check DNS, that port 443 is open to the internet, and that the TLS certificate is browser-trusted - a self-signed certificate fails here), or SLACK_SIGNING_SECRET is not set on the deployment.
OAuth step fails with redirect_uri mismatch: SLACK_REDIRECT_URI does not exactly match a redirect URL registered on the Slack app.
Events deliver but signature validation fails (401 in the deployment logs): the app’s Signing Secret and the deployed SLACK_SIGNING_SECRET do not match - re-copy it from Basic Information and re-apply.
/overcut slash command returns an error in Slack: the slash-command URL on the app does not point at https://<your-overcut-domain>/hooks/slack/slash-command, or the deployment is unreachable from Slack.
Messages in a channel do not trigger anything: the bot is not in the channel, or the channel is not registered in the project - see Register channels in a project.

For what you can do once connected (channels, routing modes, triggering workflows, interactive sessions), see the Slack overview.

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Slack from self-hosted Overcut

Prerequisites

How it works

Step 1: Create the Slack app

Step 2: Configure the deployment

Apply the configuration

Verify the event endpoint

Step 3: Connect in Overcut

Troubleshooting

​Prerequisites

​How it works

​Step 1: Create the Slack app

​Step 2: Configure the deployment

​Apply the configuration

​Verify the event endpoint

​Step 3: Connect in Overcut

​Troubleshooting

Prerequisites

How it works

Step 1: Create the Slack app

Step 2: Configure the deployment

Apply the configuration

Verify the event endpoint

Step 3: Connect in Overcut

Troubleshooting