Bug2007406 - Add server knobs config to ping_info

This adds the currently applied server knobs config to all pings in the ping_info section, or omits it if no server knobs config is applied. This should help to calculate effective sampling rates for metrics and pings that are being sampled in the client.

Author: travis79

docs/user/user/server-knobs/metrics/experimenter-configuration.md

@@ -21,3 +21,38 @@ This configuration would be what is entered into the branch configuration setup
   }
 }
 ```
+
+## Server Knobs Configuration in Pings
+
+When Server Knobs configuration is applied through `applyServerKnobsConfig`, the entire configuration is automatically recorded as an `ObjectMetric` and included in the `ping_info` section of all pings. This makes it easier to identify which metrics are being controlled by Server Knobs and to calculate effective sampling rates in analysis.
+
+The configuration is stored using a standard `ObjectMetric` (at `glean.internal.server_knobs_config`), which provides schema definition support for downstream tooling and requires minimal changes to ingestion pipeline schemas.
+
+### How It Appears in Pings
+
+The complete Server Knobs configuration is included in `ping_info.server_knobs_config`:
+
+```json
+{
+  "ping_info": {
+    "seq": 123,
+    "start_time": "2024-01-01T00:00:00Z",
+    "end_time": "2024-01-01T01:00:00Z",
+    "server_knobs_config": {
+      "metrics_enabled": {
+        "urlbar.engagement": true,
+        "urlbar.impression": true
+      },
+      "pings_enabled": {},
+      "event_threshold": null
+    }
+  },
+  "metrics": {
+    "counter": {
+      "urlbar.engagement": 5,
+      "urlbar.impression": 2
+    }
+  }
+}
+```
+

docs/user/user/server-knobs/other/max-events.md

@@ -14,3 +14,38 @@ For instance, if you wanted to disable batching in order to transmit an events p
   }
 }
 ```
+
+## Server Knobs Configuration in Pings
+
+When Server Knobs configuration is applied through `applyServerKnobsConfig`, the entire configuration is automatically recorded as an `ObjectMetric` and included in the `ping_info` section of all pings. This makes it easier to identify which metrics are being controlled by Server Knobs and to calculate effective sampling rates in analysis.
+
+The configuration is stored using a standard `ObjectMetric` (at `glean.internal.server_knobs_config`), which provides schema definition support for downstream tooling and requires minimal changes to ingestion pipeline schemas.
+
+### How It Appears in Pings
+
+The complete Server Knobs configuration is included in `ping_info.server_knobs_config`:
+
+```json
+{
+  "ping_info": {
+    "seq": 123,
+    "start_time": "2024-01-01T00:00:00Z",
+    "end_time": "2024-01-01T01:00:00Z",
+    "server_knobs_config": {
+      "metrics_enabled": {
+        "urlbar.engagement": true,
+        "urlbar.impression": true
+      },
+      "pings_enabled": {},
+      "event_threshold": null
+    }
+  },
+  "metrics": {
+    "counter": {
+      "urlbar.engagement": 5,
+      "urlbar.impression": 2
+    }
+  }
+}
+```
+

docs/user/user/server-knobs/pings/experimenter-configuration.md

@@ -19,3 +19,38 @@ This configuration would be what is entered into the branch configuration setup
   }
 }
 ```
+
+## Server Knobs Configuration in Pings
+
+When Server Knobs configuration is applied through `applyServerKnobsConfig`, the entire configuration is automatically recorded as an `ObjectMetric` and included in the `ping_info` section of all pings. This makes it easier to identify which metrics are being controlled by Server Knobs and to calculate effective sampling rates in analysis.
+
+The configuration is stored using a standard `ObjectMetric` (at `glean.internal.server_knobs_config`), which provides schema definition support for downstream tooling and requires minimal changes to ingestion pipeline schemas.
+
+### How It Appears in Pings
+
+The complete Server Knobs configuration is included in `ping_info.server_knobs_config`:
+
+```json
+{
+  "ping_info": {
+    "seq": 123,
+    "start_time": "2024-01-01T00:00:00Z",
+    "end_time": "2024-01-01T01:00:00Z",
+    "server_knobs_config": {
+      "metrics_enabled": {
+        "urlbar.engagement": true,
+        "urlbar.impression": true
+      },
+      "pings_enabled": {},
+      "event_threshold": null
+    }
+  },
+  "metrics": {
+    "counter": {
+      "urlbar.engagement": 5,
+      "urlbar.impression": 2
+    }
+  }
+}
+```
+

glean-core/metrics.yaml

@@ -398,6 +398,44 @@ glean.internal.metrics:
       - glean-team@mozilla.com
     expires: never
 
+  server_knobs_config:
+    type: object
+    lifetime: application
+    send_in_pings:
+      - glean_internal_info
+    description: |
+      The Server Knobs configuration applied via applyServerKnobsConfig.
+      This contains the complete configuration including metrics_enabled,
+      pings_enabled, and event_threshold settings that control metric
+      recording behavior through remote configuration.
+    bugs:
+      - https://bugzilla.mozilla.org/show_bug.cgi?id=2007406
+    data_reviews:
+      - https://bugzilla.mozilla.org/show_bug.cgi?id=2007406
+    data_sensitivity:
+      - technical
+    notification_emails:
+      - glean-team@mozilla.com
+    expires: never
+    structure:
+      type: object
+      properties:
+        metrics_enabled:
+          type: object
+          description: |
+            Map of metric identifiers (category.name) to boolean values
+            indicating whether the metric is enabled.
+        pings_enabled:
+          type: object
+          description: |
+            Map of ping names to boolean values indicating whether
+            the ping is enabled.
+        event_threshold:
+          type: integer
+          description: |
+            Optional threshold for event buffering before an events
+            ping is collected and submitted. Can be null if not set.
+
 
 glean.internal.metrics.attribution:
   source:

glean-core/src/core/mod.rs

@@ -1113,6 +1113,17 @@ impl Glean {
             .get_value(self, None)
     }
 
+    /// Returns the ObjectMetric used to store Server Knobs configuration.
+    pub(crate) fn server_knobs_metric() -> metrics::ObjectMetric {
+        metrics::ObjectMetric::new(CommonMetricData {
+            name: "server_knobs_config".into(),
+            category: "glean.internal".into(),
+            send_in_pings: vec![INTERNAL_STORAGE.into()],
+            lifetime: Lifetime::Application,
+            ..Default::default()
+        })
+    }
+
     /// Set configuration to override the default state, typically initiated from a
     /// remote_settings experiment or rollout
     ///
@@ -1136,6 +1147,15 @@ impl Glean {
 
         remote_settings_config.event_threshold = cfg.event_threshold;
 
+        // Store the Server Knobs configuration as an ObjectMetric
+        // This allows it to be included in pings automatically
+        let config_clone = remote_settings_config.clone();
+        drop(remote_settings_config); // Release lock before storage operation
+
+        // Store the configuration using the server knobs ObjectMetric
+        let server_knobs_metric = Self::server_knobs_metric();
+        server_knobs_metric.set_sync(self, serde_json::to_value(&config_clone).unwrap());
+
         // Update remote_settings epoch
         self.remote_settings_epoch.fetch_add(1, Ordering::SeqCst);
     }

glean-core/src/ping/mod.rs

@@ -162,6 +162,15 @@ impl PingMaker {
                 .insert("experiments".to_string(), experiment_data);
         };
 
+        // Get the Server Knobs configuration, if available.
+        let server_knobs_metric = crate::Glean::server_knobs_metric();
+        if let Some(config_json) = server_knobs_metric.get_value(glean, INTERNAL_STORAGE) {
+            let server_knobs_config = serde_json::from_str(&config_json).unwrap();
+            map.as_object_mut()
+                .unwrap() // safe unwrap, we created the object above
+                .insert("server_knobs_config".to_string(), server_knobs_config);
+        }
+
         map
     }
 
@@ -533,4 +542,70 @@ mod test {
         assert_eq!(0, ping_maker.get_ping_seq(&glean, "store1"));
         assert_eq!(1, ping_maker.get_ping_seq(&glean, "store1"));
     }
+
+    #[test]
+    fn test_server_knobs_config_appears_in_ping_info() {
+        use crate::metrics::RemoteSettingsConfig;
+        use std::collections::HashMap;
+
+        let (glean, _t) = new_glean(None);
+
+        // Apply complete Server Knobs config with all three fields
+        let mut metrics_enabled = HashMap::new();
+        metrics_enabled.insert("test.counter".to_string(), true);
+
+        let mut pings_enabled = HashMap::new();
+        pings_enabled.insert("custom".to_string(), false);
+
+        let config = RemoteSettingsConfig {
+            metrics_enabled,
+            pings_enabled,
+            event_threshold: Some(10),
+        };
+        glean.apply_server_knobs_config(config);
+
+        // Verify complete config structure appears in ping_info
+        let ping_maker = PingMaker::new();
+        let ping_info = ping_maker.get_ping_info(&glean, "store1", None, TimeUnit::Minute);
+
+        let server_knobs = &ping_info["server_knobs_config"];
+        assert_eq!(server_knobs["metrics_enabled"]["test.counter"], true);
+        assert_eq!(server_knobs["pings_enabled"]["custom"], false);
+        assert_eq!(server_knobs["event_threshold"], 10);
+    }
+
+    #[test]
+    fn test_server_knobs_not_included_when_no_config() {
+        let (glean, _t) = new_glean(None);
+
+        let ping_maker = PingMaker::new();
+        let ping_info = ping_maker.get_ping_info(&glean, "store1", None, TimeUnit::Minute);
+
+        assert!(ping_info.get("server_knobs_config").is_none());
+    }
+
+    #[test]
+    fn test_server_knobs_appears_in_all_pings() {
+        use crate::metrics::RemoteSettingsConfig;
+        use std::collections::HashMap;
+
+        let (glean, _t) = new_glean(None);
+
+        let mut metrics_enabled = HashMap::new();
+        metrics_enabled.insert("test.counter".to_string(), true);
+
+        let config = RemoteSettingsConfig {
+            metrics_enabled,
+            ..Default::default()
+        };
+        glean.apply_server_knobs_config(config);
+
+        // Verify config appears in multiple different pings
+        let ping_maker = PingMaker::new();
+        let ping_info1 = ping_maker.get_ping_info(&glean, "store1", None, TimeUnit::Minute);
+        let ping_info2 = ping_maker.get_ping_info(&glean, "store2", None, TimeUnit::Minute);
+
+        assert_eq!(ping_info1["server_knobs_config"]["metrics_enabled"]["test.counter"], true);
+        assert_eq!(ping_info2["server_knobs_config"]["metrics_enabled"]["test.counter"], true);
+    }
 }