telemetry: compile-in Azure Monitor connection string, best-effort AppInsights tracing

.pipelines/templates/stages/trident_rpms/release.yml

@@ -58,6 +58,10 @@ steps:
       version=$(echo $full_version | cut -d'-' -f1)
       prerelease=$(echo $full_version | cut -d'-' -f2-)
 
+      # Application Insights connection string identifying best-effort
+      # telemetry as coming from Trident's own CI/CD pipeline builds
+      AZURE_MONITOR_CONNECTION_STRING="InstrumentationKey=e32fc20f-2cc6-4d86-9e12-ab5d24b366f7;IngestionEndpoint=https://eastus2-3.in.applicationinsights.azure.com/;LiveEndpoint=https://eastus2.livediagnostics.monitor.azure.com/;ApplicationId=fb8e8afb-99bd-4143-ae31-22f9070005e2"
+
       # Build RPMs and export only the artifact tarball (no image load/unpack).
       # CARGO_REGISTRIES_BMP_PUBLICPACKAGES_TOKEN is populated by the CargoAuthenticate task.
       outdir="/tmp/_rpm_artifacts"
@@ -80,6 +84,7 @@ steps:
         --build-arg RPM_PACKAGES="$RPM_PACKAGES" \
         --build-arg RUST_PACKAGE="$RUST_PACKAGE" \
         --build-arg RPM_DEST="$RPM_DEST" \
+        --build-arg AZURE_MONITOR_CONNECTION_STRING="$AZURE_MONITOR_CONNECTION_STRING" \
         --target artifact \
         --output type=local,dest="$outdir" \
         .

crates/trident/build.rs

@@ -1,4 +1,5 @@
 fn main() -> Result<(), Box<dyn std::error::Error>> {
     println!("cargo:rerun-if-env-changed=TRIDENT_VERSION");
+    println!("cargo:rerun-if-env-changed=AZURE_MONITOR_CONNECTION_STRING");
     Ok(())
-}
+}

crates/trident/src/agentconfig.rs

@@ -7,30 +7,65 @@ use trident_api::{
     error::TridentError,
 };
 
+/// Whether Trident should attempt to send tracing data to Application
+/// Insights (best-effort, and only when a connection string was compiled
+/// into the binary -- see [`crate::AZURE_MONITOR_CONNECTION_STRING`]).
+///
+/// Defaults to [`TelemetryPreference::OptOut`]: telemetry is disabled unless
+/// a user has explicitly opted in via the Agent Configuration file.
+#[derive(Debug, Clone, Copy, PartialEq, Eq, Default)]
+pub enum TelemetryPreference {
+    /// Telemetry is disabled. Trident will not send any tracing data off
+    /// the host.
+    #[default]
+    OptOut,
+    /// Telemetry is enabled, best-effort, provided a connection string was
+    /// compiled into this Trident binary.
+    OptIn,
+}
+
 pub struct AgentConfig {
     datastore: PathBuf,
+    telemetry: TelemetryPreference,
 }
 
 impl AgentConfig {
     /// Load the AgentConfig from the default configuration file.
     pub fn load() -> Result<Self, TridentError> {
+        Self::load_from_path(AGENT_CONFIG_PATH)
+    }
+
+    /// Load the AgentConfig from an arbitrary path. Split out from [`load`]
+    /// so the parsing logic can be unit tested without touching
+    /// [`AGENT_CONFIG_PATH`].
+    fn load_from_path(path: &str) -> Result<Self, TridentError> {
         let mut config = Self {
             datastore: TRIDENT_DATASTORE_PATH_DEFAULT.into(),
+            telemetry: TelemetryPreference::default(),
         };
 
-        if let Ok(contents) = std::fs::read_to_string(AGENT_CONFIG_PATH) {
+        if let Ok(contents) = std::fs::read_to_string(path) {
             for line in contents.lines() {
-                if let Some(path) = line.strip_prefix("DatastorePath=") {
-                    config.datastore = path.trim().into();
+                if let Some(value) = line.strip_prefix("DatastorePath=") {
+                    config.datastore = value.trim().into();
+                } else if let Some(value) = line.strip_prefix("Telemetry=") {
+                    config.telemetry = match value.trim().to_ascii_lowercase().as_str() {
+                        "optin" => TelemetryPreference::OptIn,
+                        "optout" => TelemetryPreference::OptOut,
+                        other => {
+                            debug!(
+                                "Unrecognized Telemetry setting '{other}' in agent \
+                                 configuration file, defaulting to OptOut"
+                            );
+                            TelemetryPreference::OptOut
+                        }
+                    };
                 }
             }
         } else {
             // If the config file does not exist, we proceed with defaults.
             // Only log this at debug level to avoid alarming users unnecessarily.
-            debug!(
-                "Agent configuration file not found at {}, using defaults",
-                AGENT_CONFIG_PATH
-            );
+            debug!("Agent configuration file not found at {path}, using defaults");
         }
 
         Ok(config)
@@ -40,4 +75,85 @@ impl AgentConfig {
     pub fn datastore_path(&self) -> &Path {
         &self.datastore
     }
+
+    /// Whether telemetry (best-effort tracing to Application Insights) is
+    /// enabled per the agent configuration file. Defaults to `false`
+    /// (opt-out) when unset or unrecognized.
+    pub fn telemetry_enabled(&self) -> bool {
+        matches!(self.telemetry, TelemetryPreference::OptIn)
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn test_defaults_when_file_missing() {
+        let config = AgentConfig::load_from_path("/nonexistent/path/for/trident-tests.conf")
+            .expect("load_from_path should not fail even if the file is missing");
+        assert_eq!(
+            config.datastore_path(),
+            Path::new(TRIDENT_DATASTORE_PATH_DEFAULT)
+        );
+        assert!(
+            !config.telemetry_enabled(),
+            "telemetry must default to OptOut"
+        );
+    }
+
+    #[test]
+    fn test_telemetry_optin() {
+        let dir = tempfile::tempdir().unwrap();
+        let path = dir.path().join("trident.conf");
+        std::fs::write(&path, "Telemetry=OptIn\n").unwrap();
+
+        let config = AgentConfig::load_from_path(path.to_str().unwrap()).unwrap();
+        assert!(config.telemetry_enabled());
+    }
+
+    #[test]
+    fn test_telemetry_optout_explicit() {
+        let dir = tempfile::tempdir().unwrap();
+        let path = dir.path().join("trident.conf");
+        std::fs::write(&path, "Telemetry=OptOut\n").unwrap();
+
+        let config = AgentConfig::load_from_path(path.to_str().unwrap()).unwrap();
+        assert!(!config.telemetry_enabled());
+    }
+
+    #[test]
+    fn test_telemetry_is_case_insensitive() {
+        let dir = tempfile::tempdir().unwrap();
+        let path = dir.path().join("trident.conf");
+        std::fs::write(&path, "Telemetry=OPTIN\n").unwrap();
+
+        let config = AgentConfig::load_from_path(path.to_str().unwrap()).unwrap();
+        assert!(config.telemetry_enabled());
+    }
+
+    #[test]
+    fn test_telemetry_unrecognized_value_defaults_optout() {
+        let dir = tempfile::tempdir().unwrap();
+        let path = dir.path().join("trident.conf");
+        std::fs::write(&path, "Telemetry=maybe\n").unwrap();
+
+        let config = AgentConfig::load_from_path(path.to_str().unwrap()).unwrap();
+        assert!(!config.telemetry_enabled());
+    }
+
+    #[test]
+    fn test_datastore_and_telemetry_together() {
+        let dir = tempfile::tempdir().unwrap();
+        let path = dir.path().join("trident.conf");
+        std::fs::write(
+            &path,
+            "DatastorePath=/custom/path.sqlite\nTelemetry=OptIn\n",
+        )
+        .unwrap();
+
+        let config = AgentConfig::load_from_path(path.to_str().unwrap()).unwrap();
+        assert!(config.telemetry_enabled());
+        assert_eq!(config.datastore_path(), Path::new("/custom/path.sqlite"));
+    }
 }