feat(config): integrate etcd for service discovery and config management

- Add etcd-client dependency for distributed configuration storage
- Implement EtcdConfig with priority: etcd > environment variables > defaults
- Add ServiceRegistry for service registration with lease keep-alive
- Integrate etcd-based service discovery for appks gRPC connections
- Add service watcher for real-time service instance updates
- Migrate Redis configuration from single URL to cluster node list
- Update Dockerfile with default IMKS_HOST and IMKS_PORT environment variables
- Add etcd bootstrap configuration through environment variables
- Implement Redis cluster URL building with optional authentication

telemetry/config.rs

@@ -32,10 +32,7 @@ impl Default for TelemetryConfig {
         Self {
             service_name: env_or("OTEL_SERVICE_NAME", "imks"),
             service_version: env_or("OTEL_SERVICE_VERSION", env!("CARGO_PKG_VERSION")),
-            otlp_endpoint: env_or(
-                "OTEL_EXPORTER_OTLP_ENDPOINT",
-                "http://localhost:4317",
-            ),
+            otlp_endpoint: env_or("OTEL_EXPORTER_OTLP_ENDPOINT", "http://localhost:4317"),
             otlp_protocol: detect_otlp_protocol(),
             traces_enabled: env_bool("OTEL_TRACES_ENABLED", true),
             metrics_enabled: env_bool("OTEL_METRICS_ENABLED", true),

telemetry/health.rs

@@ -52,10 +52,7 @@ pub fn connections_active_count() -> u64 {
 
 /// Returns the server uptime in seconds.
 pub fn uptime_secs() -> u64 {
-    START_TIME
-        .get()
-        .map(|t| t.elapsed().as_secs())
-        .unwrap_or(0)
+    START_TIME.get().map(|t| t.elapsed().as_secs()).unwrap_or(0)
 }
 
 #[derive(Debug, Clone, Serialize)]
@@ -147,11 +144,7 @@ pub async fn health_check(checks: actix_web::web::Data<Arc<HealthCheckFns>>) ->
             .iter()
             .filter_map(|c| c.as_ref())
             .all(|c| c.status == "up");
-        if all_up {
-            "healthy"
-        } else {
-            "degraded"
-        }
+        if all_up { "healthy" } else { "degraded" }
     } else {
         "healthy"
     };

telemetry/logs.rs

@@ -2,12 +2,12 @@
 
 use opentelemetry_appender_tracing::layer::OpenTelemetryTracingBridge;
 use opentelemetry_otlp::{LogExporter, Protocol, WithExportConfig};
-use opentelemetry_sdk::logs::SdkLoggerProvider;
 use opentelemetry_sdk::Resource;
-use tracing_subscriber::fmt::format::FmtSpan;
-use tracing_subscriber::layer::SubscriberExt;
+use opentelemetry_sdk::logs::SdkLoggerProvider;
 use tracing_subscriber::EnvFilter;
 use tracing_subscriber::Registry;
+use tracing_subscriber::fmt::format::FmtSpan;
+use tracing_subscriber::layer::SubscriberExt;
 
 use super::config::{OtlpProtocol, TelemetryConfig};
 use crate::ImksResult;
@@ -35,7 +35,9 @@ pub fn init_subscriber(
     let (logger_provider, log_bridge_layer) = if config.logs_enabled {
         let exporter = build_log_exporter(config)?;
 
-        let resource = resource.cloned().unwrap_or_else(|| Resource::builder().build());
+        let resource = resource
+            .cloned()
+            .unwrap_or_else(|| Resource::builder().build());
 
         let provider = SdkLoggerProvider::builder()
             .with_resource(resource)
@@ -72,9 +74,7 @@ pub fn init_subscriber(
             set_subscriber(subscriber);
         }
         (None, None) => {
-            let subscriber = Registry::default()
-                .with(env_filter)
-                .with(make_json_fmt());
+            let subscriber = Registry::default().with(env_filter).with(make_json_fmt());
             set_subscriber(subscriber);
         }
     }

telemetry/metrics.rs

@@ -2,11 +2,11 @@
 
 use std::sync::OnceLock;
 
+use opentelemetry::KeyValue;
 use opentelemetry::global;
 use opentelemetry::metrics::{Counter, Histogram, Meter, UpDownCounter};
-use opentelemetry::KeyValue;
-use opentelemetry_sdk::metrics::SdkMeterProvider;
 use opentelemetry_sdk::Resource;
+use opentelemetry_sdk::metrics::SdkMeterProvider;
 use prometheus::{Encoder, Registry, TextEncoder};
 
 use crate::ImksResult;
@@ -47,7 +47,9 @@ pub fn init_metrics(
     let exporter = opentelemetry_prometheus::exporter()
         .with_registry(registry)
         .build()
-        .map_err(|e| crate::ImksError::Internal(format!("failed to build Prometheus exporter: {e}")))?;
+        .map_err(|e| {
+            crate::ImksError::Internal(format!("failed to build Prometheus exporter: {e}"))
+        })?;
 
     let provider = SdkMeterProvider::builder()
         .with_resource(resource.clone())
@@ -153,7 +155,9 @@ impl MetricsInstruments {
 ///
 /// Encodes the Prometheus text format from the shared registry.
 pub async fn metrics_handler() -> actix_web::HttpResponse {
-    let registry = PROMETHEUS_REGISTRY.get().expect("Prometheus registry not initialized");
+    let registry = PROMETHEUS_REGISTRY
+        .get()
+        .expect("Prometheus registry not initialized");
 
     let metric_families = registry.gather();
     let encoder = TextEncoder::new();

telemetry/traces.rs

@@ -2,9 +2,9 @@
 
 use opentelemetry::trace::TracerProvider as _;
 use opentelemetry_otlp::{Protocol, SpanExporter, WithExportConfig};
+use opentelemetry_sdk::Resource;
 use opentelemetry_sdk::propagation::TraceContextPropagator;
 use opentelemetry_sdk::trace::{SdkTracerProvider, Tracer};
-use opentelemetry_sdk::Resource;
 use tracing_opentelemetry::OpenTelemetryLayer;
 use tracing_subscriber::Registry;
 
@@ -24,9 +24,7 @@ fn build_span_exporter(config: &TelemetryConfig) -> ImksResult<SpanExporter> {
             .with_protocol(Protocol::HttpBinary)
             .with_endpoint(&config.otlp_endpoint)
             .build()
-            .map_err(|e| {
-                crate::ImksError::Internal(format!("OTLP HTTP span exporter: {e}"))
-            }),
+            .map_err(|e| crate::ImksError::Internal(format!("OTLP HTTP span exporter: {e}"))),
     }
 }