feat: Support export metric in remote write format (#2928)

* feat: remote write metric task

* chore: pass stanalone task to frontend

* chore: change name to system metric

* fix: add header and rename to export metrics

src/datanode/src/config.rs

@@ -28,6 +28,7 @@ use meta_client::MetaClientOptions;
 use mito2::config::MitoConfig;
 use secrecy::SecretString;
 use serde::{Deserialize, Serialize};
+use servers::export_metrics::ExportMetricsOption;
 use servers::heartbeat_options::HeartbeatOptions;
 use servers::http::HttpOptions;
 use servers::Mode;
@@ -242,6 +243,7 @@ pub struct DatanodeOptions {
     pub region_engine: Vec<RegionEngineConfig>,
     pub logging: LoggingOptions,
     pub enable_telemetry: bool,
+    pub export_metrics: ExportMetricsOption,
 }
 
 impl Default for DatanodeOptions {
@@ -267,6 +269,7 @@ impl Default for DatanodeOptions {
             logging: LoggingOptions::default(),
             heartbeat: HeartbeatOptions::datanode_default(),
             enable_telemetry: true,
+            export_metrics: ExportMetricsOption::default(),
         }
     }
 }

src/datanode/src/datanode.rs

@@ -43,6 +43,7 @@ use mito2::engine::MitoEngine;
 use object_store::manager::{ObjectStoreManager, ObjectStoreManagerRef};
 use object_store::util::normalize_dir;
 use query::QueryEngineFactory;
+use servers::export_metrics::ExportMetricsTask;
 use servers::grpc::{GrpcServer, GrpcServerConfig};
 use servers::http::HttpServerBuilder;
 use servers::metrics_handler::MetricsHandler;
@@ -84,6 +85,7 @@ pub struct Datanode {
     greptimedb_telemetry_task: Arc<GreptimeDBTelemetryTask>,
     leases_notifier: Option<Arc<Notify>>,
     plugins: Plugins,
+    export_metrics_task: Option<ExportMetricsTask>,
 }
 
 impl Datanode {
@@ -95,6 +97,10 @@ impl Datanode {
 
         self.start_telemetry();
 
+        if let Some(t) = self.export_metrics_task.as_ref() {
+            t.start()
+        }
+
         self.start_services().await
     }
 
@@ -277,6 +283,10 @@ impl DatanodeBuilder {
                 None
             };
 
+        let export_metrics_task =
+            ExportMetricsTask::try_new(&self.opts.export_metrics, Some(&self.plugins))
+                .context(StartServerSnafu)?;
+
         Ok(Datanode {
             services,
             heartbeat_task,
@@ -285,6 +295,7 @@ impl DatanodeBuilder {
             region_event_receiver,
             leases_notifier,
             plugins: self.plugins.clone(),
+            export_metrics_task,
         })
     }