[ROB-2999] Alertmanager support for gcp

docs/configuration/alertmanager-integration/google-managed-alertmanager.rst

@@ -0,0 +1,141 @@
+Google Managed Alertmanager
+===========================
+
+This guide shows how to forward alerts from Google Managed Prometheus (GMP) managed Alertmanager to Robusta using Robusta's generic Alertmanager webhook.
+
+.. note::
+
+   Every alert must carry a ``cluster_name`` label. Set it to the Robusta ``cluster_name`` configured for the target cluster, or use ``external`` when the alerts do not belong to a specific runner.
+
+   For configuring metric querying from Google Managed Prometheus, see :doc:`/configuration/metric-providers-google`. For other Alertmanager integrations, see :doc:`outofcluster-prometheus` or :doc:`alert-manager`.
+
+Requirements
+************
+
+- Robusta ``account_id`` and ``signing_key`` from your ``generated_values.yaml`` file.
+- A GMP workspace with managed Alertmanager enabled.
+
+Configure the Alertmanager webhook
+**********************************
+
+Apply the following Secret in the GMP namespace (default ``gmp-public``). Replace ``<ACCOUNT_ID>`` and ``<SIGNING_KEY>`` with your credentials.
+
+.. code-block:: yaml
+
+   apiVersion: v1
+   kind: Secret
+   metadata:
+     name: alertmanager
+     namespace: gmp-public
+   type: Opaque
+   stringData:
+     alertmanager.yaml: |
+       receivers:
+         - name: 'robusta'
+           webhook_configs:
+             - url: 'https://api.robusta.dev/integrations/generic/alertmanager'
+               http_config:
+                 authorization:
+                   # Replace <ACCOUNT_ID> <SIGNING_KEY>, with your account_id and signing_key
+                   credentials: 'Bearer <ACCOUNT_ID> <SIGNING_KEY>'
+               send_resolved: true
+
+       route:
+         receiver: 'robusta'
+         group_by: ['...']
+         group_wait: 1s
+         group_interval: 1s
+         repeat_interval: 4h
+
+Ensure alerts include ``cluster_name``
+*************************************
+
+Use an ``OperatorConfig`` to add external labels to both collection and rule evaluation so every alert contains the required ``cluster_name`` label.
+
+.. code-block:: yaml
+
+   apiVersion: monitoring.googleapis.com/v1
+   kind: OperatorConfig
+   metadata:
+     name: config
+     namespace: gmp-public
+   collection:
+     externalLabels:
+       cluster_name: gmp-demo-cluster   # Match your Robusta cluster_name, or use "external"
+       location: us-central1-c
+       project_id: my-gcp-project
+   rules:
+     externalLabels:
+       cluster_name: gmp-demo-cluster
+       location: us-central1-c
+       project_id: my-gcp-project
+
+Deploy a demo alert
+*******************
+
+Create a simple alerting rule to confirm delivery to Robusta.
+
+.. code-block:: yaml
+
+   apiVersion: monitoring.googleapis.com/v1
+   kind: Rules
+   metadata:
+     name: test-alert
+     namespace: gmp-public
+   spec:
+     groups:
+       - name: test
+         interval: 30s
+         rules:
+           - alert: TestAlertForGCPAlertmanager
+             expr: vector(1)
+             for: 0m
+             labels:
+               severity: warning
+             annotations:
+               summary: "Test alert to verify Alertmanager webhook"
+               description: "This is a test alert. Delete the Rules resource to stop it."
+
+Optional: verify credentials with curl
+**************************************
+
+You can manually validate the webhook and credentials by posting a sample alert:
+
+.. code-block:: bash
+
+   curl -X POST 'https://api.robusta.dev/integrations/generic/alertmanager' \
+     -H 'Authorization: Bearer <ACCOUNT_ID> <SIGNING_KEY>' \
+     -H 'Content-Type: application/json' \
+     -d '{
+     "externalURL": "https://console.cloud.google.com/monitoring",
+     "groupKey": "gmp/test-alert:gmp-webhook-test-001",
+     "version": "1",
+     "status": "firing",
+     "receiver": "robusta",
+     "alerts": [
+       {
+         "status": "firing",
+         "startsAt": "2026-01-13T13:30:50Z",
+         "endsAt": "1970-01-01T00:00:00Z",
+         "generatorURL": "https://console.cloud.google.com/monitoring",
+         "source": "GMP",
+         "description": "Test alert to verify GMP Alertmanager webhook configuration",
+         "fingerprint": "gmp-test-alert-12345",
+         "annotations": {
+           "summary": "GMP Webhook Test Alert",
+           "description": "If you see this in Robusta, the webhook URL and credentials are working correctly!"
+         },
+         "labels": {
+           "cluster_name": "external",
+           "cluster": "external",
+           "alertname": "GMP_WebhookTest",
+           "severity": "warning",
+           "namespace": "gmp-public",
+           "source": "gmp-managed-alertmanager"
+         }
+       }
+     ]
+   }'
+
+You should see the test alert in Robusta shortly after applying the resources or running the curl command.
+

docs/configuration/alertmanager-integration/google-managed-prometheus.rst

@@ -9,6 +9,10 @@ Google Managed Prometheus Alerts
 
 This guide shows how to send alerts from `Google Managed Prometheus <https://cloud.google.com/stackdriver/docs/managed-prometheus>`_ to Robusta.
 
+.. note::
+
+   **Using Google Managed Alertmanager?** For Google Managed Prometheus (GMP) managed Alertmanager, see the dedicated guide: :doc:`google-managed-alertmanager`
+
 For configuring metric querying from Google Managed Prometheus, see :doc:`/configuration/metric-providers-google`.
 
 Prerequisites

docs/configuration/index.rst

@@ -46,6 +46,11 @@ Prometheus & AlertManager
         :link: alertmanager-integration/google-managed-prometheus
         :link-type: doc
 
+    .. grid-item-card:: :octicon:`pulse;1em;` Google Managed Alertmanager
+        :class-card: sd-bg-light sd-bg-text-light
+        :link: alertmanager-integration/google-managed-alertmanager
+        :link-type: doc
+
     .. grid-item-card:: :octicon:`pulse;1em;` Grafana - Self-Hosted
         :class-card: sd-bg-light sd-bg-text-light
         :link: alertmanager-integration/grafana-self-hosted

docs/configuration/metric-providers-google.rst

@@ -93,5 +93,6 @@ Next Steps
 ----------
 
 - Configure :doc:`alert routing </notification-routing/index>`
-- Set up :doc:`Google Cloud alerting integration </configuration/alertmanager-integration/google-managed-prometheus>`
+- Set up :doc:`Google Managed Alertmanager integration </configuration/alertmanager-integration/google-managed-alertmanager>` (recommended for GMP managed Alertmanager)
+- Set up :doc:`Google Cloud alerting integration </configuration/alertmanager-integration/google-managed-prometheus>` (legacy guide)
 - Learn about :doc:`common configuration options <metric-providers>`