Merge #3524

3524: Update the metrics route r=irevoire a=irevoire

Fixes #3523

Make the metrics available by default without a feature flag.
+ Rename the cli-flag to `experimental-enable-metrics`.

Co-authored-by: Tamo <tamo@meilisearch.com>

meilisearch/src/routes/metrics.rs

@@ -0,0 +1,45 @@
+use actix_web::http::header;
+use actix_web::web::{self, Data};
+use actix_web::HttpResponse;
+use index_scheduler::IndexScheduler;
+use meilisearch_auth::{AuthController, AuthFilter};
+use meilisearch_types::error::ResponseError;
+use meilisearch_types::keys::actions;
+use prometheus::{Encoder, TextEncoder};
+
+use crate::extractors::authentication::policies::ActionPolicy;
+use crate::extractors::authentication::GuardedData;
+use crate::routes::create_all_stats;
+
+pub fn configure(config: &mut web::ServiceConfig) {
+    config.service(web::resource("").route(web::get().to(get_metrics)));
+}
+
+pub async fn get_metrics(
+    index_scheduler: GuardedData<ActionPolicy<{ actions::METRICS_GET }>, Data<IndexScheduler>>,
+    auth_controller: GuardedData<ActionPolicy<{ actions::METRICS_GET }>, AuthController>,
+) -> Result<HttpResponse, ResponseError> {
+    let response = create_all_stats(
+        (*index_scheduler).clone(),
+        (*auth_controller).clone(),
+        // we don't use the filters contained in the `ActionPolicy` because the metrics must have the right to access all the indexes.
+        &AuthFilter::default(),
+    )?;
+
+    crate::metrics::MEILISEARCH_DB_SIZE_BYTES.set(response.database_size as i64);
+    crate::metrics::MEILISEARCH_INDEX_COUNT.set(response.indexes.len() as i64);
+
+    for (index, value) in response.indexes.iter() {
+        crate::metrics::MEILISEARCH_INDEX_DOCS_COUNT
+            .with_label_values(&[index])
+            .set(value.number_of_documents as i64);
+    }
+
+    let encoder = TextEncoder::new();
+    let mut buffer = vec![];
+    encoder.encode(&prometheus::gather(), &mut buffer).expect("Failed to encode metrics");
+
+    let response = String::from_utf8(buffer).expect("Failed to convert bytes to string");
+
+    Ok(HttpResponse::Ok().insert_header(header::ContentType(mime::TEXT_PLAIN)).body(response))
+}

meilisearch/src/routes/mod.rs

@@ -22,11 +22,12 @@ const PAGINATION_DEFAULT_LIMIT: usize = 20;
 mod api_key;
 mod dump;
 pub mod indexes;
+mod metrics;
 mod multi_search;
 mod swap_indexes;
 pub mod tasks;
 
-pub fn configure(cfg: &mut web::ServiceConfig) {
+pub fn configure(cfg: &mut web::ServiceConfig, enable_metrics: bool) {
     cfg.service(web::scope("/tasks").configure(tasks::configure))
         .service(web::resource("/health").route(web::get().to(get_health)))
         .service(web::scope("/keys").configure(api_key::configure))
@@ -36,6 +37,10 @@ pub fn configure(cfg: &mut web::ServiceConfig) {
         .service(web::scope("/indexes").configure(indexes::configure))
         .service(web::scope("/multi-search").configure(multi_search::configure))
         .service(web::scope("/swap-indexes").configure(swap_indexes::configure));
+
+    if enable_metrics {
+        cfg.service(web::scope("/metrics").configure(metrics::configure));
+    }
 }
 
 #[derive(Debug, Serialize)]