hive-c0re: export the agent's unrestricted internet flag as a gauge

hive-c0re/src/stats/otel_metrics.rs

@@ -39,6 +39,7 @@ use opentelemetry_sdk::metrics::{PeriodicReader, SdkMeterProvider};
 
 use super::container_stats::{self, ContainerResource};
 use super::warnings;
+use crate::permissions;
 
 /// Export cadence, and the snapshot refresher's.
 const EXPORT_INTERVAL: Duration = Duration::from_mins(1);
@@ -223,7 +224,7 @@ fn register_instruments(provider: &SdkMeterProvider, snapshot: Arc<Mutex<Vec<Con
         })
         .build();
 
-    let snap = snapshot;
+    let snap = snapshot.clone();
     meter
         .f64_observable_gauge("hyperhive.container.cpu.percent")
         .with_unit("%")
@@ -236,9 +237,34 @@ fn register_instruments(provider: &SdkMeterProvider, snapshot: Arc<Mutex<Vec<Con
         })
         .build();
 
+    // 1 when the agent's traffic may leave the host unfiltered. Read from the
+    // stored swarm permissions at each export; when that file can't be read
+    // the callback reports nothing rather than a guess.
+    let snap = snapshot;
+    meter
+        .u64_observable_gauge("hyperhive.agent.unrestricted_internet")
+        .with_unit("1")
+        .with_callback(move |obs| {
+            let Ok(stored) = permissions::read_at(&permissions::path()) else {
+                return;
+            };
+            if let Ok(g) = snap.lock() {
+                for c in g.iter() {
+                    obs.observe(unrestricted_value(&stored, &c.name), &attrs(c));
+                }
+            }
+        })
+        .build();
+
     register_hive_instruments(&meter);
 }
 
+/// The gauge value for `agent`: 1 when unrestricted, 0 when not. An agent
+/// missing from `stored` reads 1.
+fn unrestricted_value(stored: &permissions::Stored, agent: &str) -> u64 {
+    u64::from(permissions::unrestricted_internet(stored.get(agent)))
+}
+
 /// Register the instruments whose subject is **this hive**, not a container in
 /// it. Each observes with an empty attribute set (`hive` / `swarm` ride the
 /// resource), so no data point here carries `agent` — see the module doc for
@@ -519,6 +545,29 @@ mod tests {
         );
     }
 
+    #[test]
+    fn unrestricted_gauge_reads_absent_as_one() {
+        let record = |json: &str| serde_json::from_str(json).expect("decodes");
+        let stored = permissions::Stored::from([
+            (
+                "closed".to_owned(),
+                record(r#"{"unrestricted_internet":false}"#),
+            ),
+            (
+                "open".to_owned(),
+                record(r#"{"unrestricted_internet":true}"#),
+            ),
+            (
+                "legacy".to_owned(),
+                record(r#"{"permissions":["web_tools"]}"#),
+            ),
+        ]);
+        assert_eq!(unrestricted_value(&stored, "absent"), 1, "no record");
+        assert_eq!(unrestricted_value(&stored, "legacy"), 1, "flag unset");
+        assert_eq!(unrestricted_value(&stored, "open"), 1);
+        assert_eq!(unrestricted_value(&stored, "closed"), 0);
+    }
+
     /// A healthy hive still reports every level, at zero. Reporting only the
     /// levels currently raised would make a healthy hive and a hive that has
     /// stopped exporting produce the same thing — no series.