Expose fingerprint hash to metrics in redis store (#1347)

To allow external services to know what the active fingerprint is to
query redis directly, we expose the fingerprint hash via metrics.

nativelink-store/BUILD.bazel

@@ -102,6 +102,7 @@ rust_test_suite(
         "//nativelink-config",
         "//nativelink-error",
         "//nativelink-metric",
+        "//nativelink-metric-collector",
         "//nativelink-proto",
         "//nativelink-util",
         "@crates//:async-lock",
@@ -123,11 +124,13 @@ rust_test_suite(
         "@crates//:parking_lot",
         "@crates//:pretty_assertions",
         "@crates//:rand",
+        "@crates//:serde_json",
         "@crates//:serial_test",
         "@crates//:sha2",
         "@crates//:tokio",
         "@crates//:tokio-stream",
         "@crates//:tracing",
+        "@crates//:tracing-subscriber",
         "@crates//:uuid",
     ],
 )

nativelink-store/Cargo.toml

@@ -60,6 +60,7 @@ uuid = { version = "1.8.0", default-features = false, features = ["v4", "serde"]
 
 [dev-dependencies]
 nativelink-macro = { path = "../nativelink-macro" }
+nativelink-metric-collector = { path = "../nativelink-metric-collector" }
 pretty_assertions = { version = "1.4.0", features = ["std"] }
 memory-stats = "1.2.0"
 mock_instant = "0.3.2"
@@ -77,4 +78,6 @@ aws-smithy-runtime-api = "=1.7.1"
 serial_test = { version = "3.1.1", features = [
   "async",
 ], default-features = false }
+serde_json = "1.0.128"
 fred = { version = "9.1.2", default-features = false, features = ["mocks"] }
+tracing-subscriber = { version = "0.3.18", default-features = false }

nativelink-store/src/redis_store.rs

@@ -55,19 +55,33 @@ use crate::redis_utils::ft_aggregate;
 pub const READ_CHUNK_SIZE: usize = 64 * 1024;
 const CONNECTION_POOL_SIZE: usize = 3;
 
+fn to_hex(value: &u32) -> String {
+    format!("{value:08x}")
+}
+
 /// A [`StoreDriver`] implementation that uses Redis as a backing store.
 #[derive(MetricsComponent)]
 pub struct RedisStore {
     /// The client pool connecting to the backing Redis instance(s).
     client_pool: RedisPool,
 
     /// A channel to publish updates to when a key is added, removed, or modified.
+    #[metric(
+        help = "The pubsub channel to publish updates to when a key is added, removed, or modified"
+    )]
     pub_sub_channel: Option<String>,
 
     /// A redis client for managing subscriptions.
     /// TODO: This should be moved into the store in followups once a standard use pattern has been determined.
     subscriber_client: SubscriberClient,
 
+    /// For metrics only.
+    #[metric(
+        help = "A unique identifier for the FT.CREATE command used to create the index template",
+        handler = to_hex
+    )]
+    fingerprint_create_index: u32,
+
     /// A function used to generate names for temporary keys.
     temp_name_generator_fn: fn() -> String,
 
@@ -159,6 +173,7 @@ impl RedisStore {
             client_pool,
             pub_sub_channel,
             subscriber_client,
+            fingerprint_create_index: fingerprint_create_index_template(),
             temp_name_generator_fn,
             key_prefix,
             update_if_version_matches_script: Script::from_lua(LUA_VERSION_SET_SCRIPT),

nativelink-store/tests/redis_store_test.rs

@@ -25,13 +25,19 @@ use fred::prelude::Builder;
 use fred::types::{RedisConfig, RedisValue};
 use nativelink_error::{Code, Error};
 use nativelink_macro::nativelink_test;
+use nativelink_metric::{MetricFieldData, MetricKind, MetricsComponent, RootMetricsComponent};
+use nativelink_metric_collector::MetricsCollectorLayer;
 use nativelink_store::cas_utils::ZERO_BYTE_DIGESTS;
 use nativelink_store::redis_store::{RedisStore, READ_CHUNK_SIZE};
+use nativelink_store::store_manager::StoreManager;
 use nativelink_util::buf_channel::make_buf_channel_pair;
 use nativelink_util::common::DigestInfo;
-use nativelink_util::store_trait::{StoreLike, UploadSizeInfo};
+use nativelink_util::store_trait::{Store, StoreLike, UploadSizeInfo};
+use parking_lot::RwLock;
 use pretty_assertions::assert_eq;
+use serde_json::{from_str, to_string, Value};
 use tokio::sync::watch;
+use tracing_subscriber::layer::SubscriberExt;
 
 const VALID_HASH1: &str = "3031323334353637383961626364656630303030303030303030303030303030";
 const TEMP_UUID: &str = "550e8400-e29b-41d4-a716-446655440000";
@@ -664,3 +670,66 @@ async fn dont_loop_forever_on_empty() -> Result<(), Error> {
 
     Ok(())
 }
+
+#[nativelink_test]
+async fn test_redis_fingerprint_metric() -> Result<(), Error> {
+    let expected_fingerprint_value: String = String::from("3e762c15");
+
+    let store_manager = Arc::new(StoreManager::new());
+
+    {
+        let store = {
+            let mut builder = Builder::default_centralized();
+            builder.set_config(RedisConfig {
+                mocks: Some(Arc::new(MockRedisBackend::new()) as Arc<dyn Mocks>),
+                ..Default::default()
+            });
+
+            Store::new(Arc::new(RedisStore::new_from_builder_and_parts(
+                builder,
+                None,
+                mock_uuid_generator,
+                String::new(),
+            )?))
+        };
+
+        store_manager.add_store("redis_store", store);
+    };
+
+    let root_metrics = Arc::new(RwLock::new(RootMetricsTest {
+        stores: store_manager.clone(),
+    }));
+
+    let (layer, output_metrics) = MetricsCollectorLayer::new();
+
+    tracing::subscriber::with_default(tracing_subscriber::registry().with(layer), || {
+        let metrics_component = root_metrics.read();
+        MetricsComponent::publish(
+            &*metrics_component,
+            MetricKind::Component,
+            MetricFieldData::default(),
+        )
+    })
+    .unwrap();
+
+    let output_json_data = to_string(&*output_metrics.lock()).unwrap();
+
+    let parsed_output: Value = from_str(&output_json_data).unwrap();
+
+    let fingerprint_create_index = parsed_output["stores"]["redis_store"]
+        ["fingerprint_create_index"]
+        .as_str()
+        .expect("fingerprint_create_index should be a hex string");
+
+    assert_eq!(fingerprint_create_index, expected_fingerprint_value);
+
+    Ok(())
+}
+
+#[derive(MetricsComponent)]
+struct RootMetricsTest {
+    #[metric(group = "stores")]
+    stores: Arc<dyn RootMetricsComponent>,
+}
+
+impl RootMetricsComponent for RootMetricsTest {}