move prometheus behind a feature flag

meilisearch-http/src/route_metrics.rs

@@ -1,11 +1,48 @@
 use std::future::{ready, Ready};
 
+use actix_web::http::header;
+use actix_web::HttpResponse;
 use actix_web::{
     dev::{self, Service, ServiceRequest, ServiceResponse, Transform},
     Error,
 };
 use futures_util::future::LocalBoxFuture;
+use meilisearch_auth::actions;
+use meilisearch_lib::MeiliSearch;
+use meilisearch_types::error::ResponseError;
 use prometheus::HistogramTimer;
+use prometheus::{Encoder, TextEncoder};
+
+use crate::extractors::authentication::policies::ActionPolicy;
+use crate::extractors::authentication::GuardedData;
+
+pub async fn get_metrics(
+    meilisearch: GuardedData<ActionPolicy<{ actions::METRICS_GET }>, MeiliSearch>,
+) -> Result<HttpResponse, ResponseError> {
+    let search_rules = &meilisearch.filters().search_rules;
+    let response = meilisearch.get_all_stats(search_rules).await?;
+
+    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))
+}
 
 pub struct RouteMetrics;