MeiliSearch/meilisearch/src/metrics.rs

use lazy_static::lazy_static;
use prometheus::{
    opts, register_histogram_vec, register_int_counter_vec, register_int_gauge,
    register_int_gauge_vec, HistogramVec, IntCounterVec, IntGauge, IntGaugeVec,
};

/// Create evenly distributed buckets
fn create_buckets() -> [f64; 29] {
    (0..10)
        .chain((10..100).step_by(10))
        .chain((100..=1000).step_by(100))
        .map(|i| i as f64 / 1000.)
        .collect::<Vec<_>>()
        .try_into()
        .unwrap()
}

lazy_static! {
    pub static ref HTTP_RESPONSE_TIME_CUSTOM_BUCKETS: [f64; 29] = create_buckets();
    pub static ref MEILISEARCH_HTTP_REQUESTS_TOTAL: IntCounterVec = register_int_counter_vec!(
        opts!("meilisearch_http_requests_total", "Meilisearch HTTP requests total"),
        &["method", "path"]
    )
    .expect("Can't create a metric");
    pub static ref MEILISEARCH_DB_SIZE_BYTES: IntGauge =
        register_int_gauge!(opts!("meilisearch_db_size_bytes", "Meilisearch Db Size In Bytes"))
            .expect("Can't create a metric");
    pub static ref MEILISEARCH_INDEX_COUNT: IntGauge =
        register_int_gauge!(opts!("meilisearch_index_count", "Meilisearch Index Count"))
            .expect("Can't create a metric");
    pub static ref MEILISEARCH_INDEX_DOCS_COUNT: IntGaugeVec = register_int_gauge_vec!(
        opts!("meilisearch_index_docs_count", "Meilisearch Index Docs Count"),
        &["index"]
    )
    .expect("Can't create a metric");
    pub static ref MEILISEARCH_HTTP_RESPONSE_TIME_SECONDS: HistogramVec = register_histogram_vec!(
        "http_response_time_seconds",
        "HTTP response times",
        &["method", "path"],
        HTTP_RESPONSE_TIME_CUSTOM_BUCKETS.to_vec()
    )
    .expect("Can't create a metric");
    pub static ref MEILISEARCH_NB_TASKS: IntGaugeVec = register_int_gauge_vec!(
        opts!("meilisearch_nb_tasks", "Meilisearch Number of tasks"),
        &["kind", "value"]
    )
    .expect("Can't create a metric");
}