Event subscriptions

Event subscriptions allow you to receive messages when events occur across your Cloudflare account. Cloudflare products (e.g., KV, Workers AI, Workers) can publish structured events to a queue, which you can then consume with Workers or HTTP pull consumers to build custom workflows, integrations, or logic.

For more information on Event Subscriptions, refer to the management guide.

Send build notifications

You can deploy a Worker that consumes build events and sends notifications to Slack, Discord, or any webhook endpoint:

The template sends notifications for:

• Successful builds with preview or live deployment URLs
• Failed builds with error messages
• Cancelled builds

You can customize the Worker to format messages for your webhook provider. For setup instructions, refer to the template README ↗.

Available Workers Builds events

build.started

Triggered when a build starts.

Example:

{
  "type": "cf.workersBuilds.worker.build.started",
  "source": {
    "type": "workersBuilds.worker",
    "workerName": "my-worker"
  },
  "payload": {
    "buildUuid": "build-12345678-90ab-cdef-1234-567890abcdef",
    "status": "running",
    "buildOutcome": null,
    "createdAt": "2025-05-01T02:48:57.132Z",
    "initializingAt": "2025-05-01T02:48:58.132Z",
    "runningAt": "2025-05-01T02:48:59.132Z",
    "stoppedAt": null,
    "buildTriggerMetadata": {
      "buildTriggerSource": "push_event",
      "branch": "main",
      "commitHash": "abc123def456",
      "commitMessage": "Fix bug in authentication",
      "author": "developer@example.com",
      "buildCommand": "npm run build",
      "deployCommand": "wrangler deploy",
      "rootDirectory": "/",
      "repoName": "my-worker-repo",
      "providerAccountName": "github-user",
      "providerType": "github"
    }
  },
  "metadata": {
    "accountId": "f9f79265f388666de8122cfb508d7776",
    "eventSubscriptionId": "1830c4bb612e43c3af7f4cada31fbf3f",
    "eventSchemaVersion": 1,
    "eventTimestamp": "2025-05-01T02:48:57.132Z"
  }
}

build.failed

Triggered when a build fails.

Example:

{
  "type": "cf.workersBuilds.worker.build.failed",
  "source": {
    "type": "workersBuilds.worker",
    "workerName": "my-worker"
  },
  "payload": {
    "buildUuid": "build-12345678-90ab-cdef-1234-567890abcdef",
    "status": "failed",
    "buildOutcome": "failure",
    "createdAt": "2025-05-01T02:48:57.132Z",
    "initializingAt": "2025-05-01T02:48:58.132Z",
    "runningAt": "2025-05-01T02:48:59.132Z",
    "stoppedAt": "2025-05-01T02:50:00.132Z",
    "buildTriggerMetadata": {
      "buildTriggerSource": "push_event",
      "branch": "main",
      "commitHash": "abc123def456",
      "commitMessage": "Fix bug in authentication",
      "author": "developer@example.com",
      "buildCommand": "npm run build",
      "deployCommand": "wrangler deploy",
      "rootDirectory": "/",
      "repoName": "my-worker-repo",
      "providerAccountName": "github-user",
      "providerType": "github"
    }
  },
  "metadata": {
    "accountId": "f9f79265f388666de8122cfb508d7776",
    "eventSubscriptionId": "1830c4bb612e43c3af7f4cada31fbf3f",
    "eventSchemaVersion": 1,
    "eventTimestamp": "2025-05-01T02:48:57.132Z"
  }
}

build.canceled

Triggered when a build is canceled.

Example:

{
  "type": "cf.workersBuilds.worker.build.canceled",
  "source": {
    "type": "workersBuilds.worker",
    "workerName": "my-worker"
  },
  "payload": {
    "buildUuid": "build-12345678-90ab-cdef-1234-567890abcdef",
    "status": "canceled",
    "buildOutcome": "canceled",
    "createdAt": "2025-05-01T02:48:57.132Z",
    "initializingAt": "2025-05-01T02:48:58.132Z",
    "runningAt": "2025-05-01T02:48:59.132Z",
    "stoppedAt": "2025-05-01T02:49:30.132Z",
    "buildTriggerMetadata": {
      "buildTriggerSource": "push_event",
      "branch": "main",
      "commitHash": "abc123def456",
      "commitMessage": "Fix bug in authentication",
      "author": "developer@example.com",
      "buildCommand": "npm run build",
      "deployCommand": "wrangler deploy",
      "rootDirectory": "/",
      "repoName": "my-worker-repo",
      "providerAccountName": "github-user",
      "providerType": "github"
    }
  },
  "metadata": {
    "accountId": "f9f79265f388666de8122cfb508d7776",
    "eventSubscriptionId": "1830c4bb612e43c3af7f4cada31fbf3f",
    "eventSchemaVersion": 1,
    "eventTimestamp": "2025-05-01T02:48:57.132Z"
  }
}

build.succeeded

Triggered when a build succeeds.

Example:

{
  "type": "cf.workersBuilds.worker.build.succeeded",
  "source": {
    "type": "workersBuilds.worker",
    "workerName": "my-worker"
  },
  "payload": {
    "buildUuid": "build-12345678-90ab-cdef-1234-567890abcdef",
    "status": "success",
    "buildOutcome": "success",
    "createdAt": "2025-05-01T02:48:57.132Z",
    "initializingAt": "2025-05-01T02:48:58.132Z",
    "runningAt": "2025-05-01T02:48:59.132Z",
    "stoppedAt": "2025-05-01T02:50:15.132Z",
    "buildTriggerMetadata": {
      "buildTriggerSource": "push_event",
      "branch": "main",
      "commitHash": "abc123def456",
      "commitMessage": "Fix bug in authentication",
      "author": "developer@example.com",
      "buildCommand": "npm run build",
      "deployCommand": "wrangler deploy",
      "rootDirectory": "/",
      "repoName": "my-worker-repo",
      "providerAccountName": "github-user",
      "providerType": "github"
    }
  },
  "metadata": {
    "accountId": "f9f79265f388666de8122cfb508d7776",
    "eventSubscriptionId": "1830c4bb612e43c3af7f4cada31fbf3f",
    "eventSchemaVersion": 1,
    "eventTimestamp": "2025-05-01T02:48:57.132Z"
  }
}