/webhook-subscriptions

name: webhook-subscriptions
description: Create and manage webhook subscriptions for event-driven agent activation. Use when the user wants external services to trigger agent runs automatically.
version: 1.0.0
metadata:
  hermes:
    tags: [webhook, events, automation, integrations]

Webhook Subscriptions

Create dynamic webhook subscriptions so external services (GitHub, GitLab, Stripe, CI/CD, IoT sensors, monitoring tools) can trigger Hermes agent runs by POSTing events to a URL.

Setup (Required First)

The webhook platform must be enabled before subscriptions can be created. Check with:

hermes webhook list

If it says "Webhook platform is not enabled", set it up:

Option 1: Setup wizard

hermes gateway setup

Follow the prompts to enable webhooks, set the port, and set a global HMAC secret.

Option 2: Manual config

Add to `~/.hermes/config.yaml`:

platforms:
  webhook:
    enabled: true
    extra:
      host: "0.0.0.0"
      port: 8644
      secret: "generate-a-strong-secret-here"

Option 3: Environment variables

Add to `~/.hermes/.env`:

WEBHOOK_ENABLED=true
WEBHOOK_PORT=8644
WEBHOOK_SECRET=generate-a-strong-secret-here

After configuration, start (or restart) the gateway:

hermes gateway run
# Or if using systemd:
systemctl --user restart hermes-gateway

Verify it's running:

curl http://localhost:8644/health

Commands

All management is via the `hermes webhook` CLI command:

Create a subscription

hermes webhook subscribe <name> \
  --prompt "Prompt template with {payload.fields}" \
  --events "event1,event2" \
  --description "What this does" \
  --skills "skill1,skill2" \
  --deliver telegram \
  --deliver-chat-id "12345" \
  --secret "optional-custom-secret"

Returns the webhook URL and HMAC secret. The user configures their service to POST to that URL.

List subscriptions

hermes webhook list

Remove a subscription

hermes webhook remove <name>

Test a subscription

hermes webhook test <name>
hermes webhook test <name> --payload '{"key": "value"}'

Prompt Templates

Prompts support `{dot.notation}` for accessing nested payload fields:

• `{issue.title}` — GitHub issue title
• `{pull_request.user.login}` — PR author
• `{data.object.amount}` — Stripe payment amount
• `{sensor.temperature}` — IoT sensor reading

If no prompt is specified, the full JSON payload is dumped into the agent prompt.

Common Patterns

GitHub: new issues

hermes webhook subscribe github-issues \
  --events "issues" \
  --prompt "New GitHub issue #{issue.number}: {issue.title}\n\nAction: {action}\nAuthor: {issue.user.login}\nBody:\n{issue.body}\n\nPlease triage this issue." \
  --deliver telegram \
  --deliver-chat-id "-100123456789"

Then in GitHub repo Settings → Webhooks → Add webhook:

• Payload URL: the returned webhook_url
• Content type: application/json
• Secret: the returned secret
• Events: "Issues"

GitHub: PR reviews

hermes webhook subscribe github-prs \
  --events "pull_request" \
  --prompt "PR #{pull_request.number} {action}: {pull_request.title}\nBy: {pull_request.user.login}\nBranch: {pull_request.head.ref}\n\n{pull_request.body}" \
  --skills "github-code-review" \
  --deliver github_comment

Stripe: payment events

hermes webhook subscribe stripe-payments \
  --events "payment_intent.succeeded,payment_intent.payment_failed" \
  --prompt "Payment {data.object.status}: {data.object.amount} cents from {data.object.receipt_email}" \
  --deliver telegram \
  --deliver-chat-id "-100123456789"

CI/CD: build notifications

hermes webhook subscribe ci-builds \
  --events "pipeline" \
  --prompt "Build {object_attributes.status} on {project.name} branch {object_attributes.ref}\nCommit: {commit.message}" \
  --deliver discord \
  --deliver-chat-id "1234567890"

Generic monitoring alert

hermes webhook subscribe alerts \
  --prompt "Alert: {alert.name}\nSeverity: {alert.severity}\nMessage: {alert.message}\n\nPlease investigate and suggest remediation." \
  --deliver origin

Security

• Each subscription gets an auto-generated HMAC-SHA256 secret (or provide your own with `--secret`)
• The webhook adapter validates signatures on every incoming POST
• Static routes from config.yaml cannot be overwritten by dynamic subscriptions
• Subscriptions persist to `~/.hermes/webhook_subscriptions.json`

How It Works

1. `hermes webhook subscribe` writes to `~/.hermes/webhook_subscriptions.json` 2. The webhook adapter hot-reloads this file on each incoming request (mtime-gated, negligible overhead) 3. When a POST arrives matching a route, the adapter formats the prompt and triggers an agent run 4. The agent's response is delivered to the configured target (Telegram, Discord, GitHub comment, etc.)

Troubleshooting

If webhooks aren't working:

1. **Is the gateway running?** Check with `systemctl --user status hermes-gateway` or `ps aux | grep gateway` 2. **Is the webhook server listening?** `curl http://localhost:8644/health` should return `{"status": "ok"}` 3. **Check gateway logs:** `grep webhook ~/.hermes/logs/gateway.log | tail -20` 4. **Signature mismatch?** Verify the secret in your service matches the one from `hermes webhook list`. GitHub sends `X-Hub-Signature-256`, GitLab sends `X-Gitlab-Token`. 5. **Firewall/NAT?** The webhook URL must be reachable from the service. For local development, use a tunnel (ngrok, cloudflared). 6. **Wrong event type?** Check `--events` filter matches what the service sends. Use `hermes webhook test <name>` to verify the route works.