Manage Alertmanager silences programmatically via the Alertmanager HTTP API

Steps

1. List existing silences with GET /api/v2/silences (optionally filtered), and fetch a single silence with GET /api/v2/silence/{silenceID}.
2. Create a silence with POST /api/v2/silences, sending a JSON body containing matchers (each with name, value, isRegex/isEqual), startsAt and endsAt as RFC3339 timestamps, createdBy, and comment; the response returns the generated silenceID.
3. To update a silence, POST /api/v2/silences again including the existing silence's id in the payload, which effectively expires the old one and creates a replacement with the new id.
4. Expire (delete) an active silence with DELETE /api/v2/silence/{silenceID}; this marks it expired rather than physically removing history immediately.
5. Use the amtool CLI (amtool silence add/query/expire) as a reference client if you want to confirm the exact JSON matcher/label formats the API expects.
6. Authenticate/network-restrict access to the API as needed (Alertmanager itself has no built-in auth), typically via a reverse proxy in front of the :9093 API port.