feat: implement parse_query api

Cargo.toml

@@ -144,7 +144,7 @@ parquet = { version = "51.0.0", default-features = false, features = ["arrow", "
 paste = "1.0"
 pin-project = "1.0"
 prometheus = { version = "0.13.3", features = ["process"] }
-promql-parser = { version = "0.4.1" }
+promql-parser = { version = "0.4.3", features = ["ser"] }
 prost = "0.12"
 raft-engine = { version = "0.4.1", default-features = false }
 rand = "0.8"

src/servers/src/http.rs

@@ -62,8 +62,8 @@ use crate::http::influxdb::{influxdb_health, influxdb_ping, influxdb_write_v1, i
 use crate::http::influxdb_result_v1::InfluxdbV1Response;
 use crate::http::json_result::JsonResponse;
 use crate::http::prometheus::{
-    build_info_query, format_query, instant_query, label_values_query, labels_query, range_query,
-    series_query,
+    build_info_query, format_query, instant_query, label_values_query, labels_query, parse_query,
+    range_query, series_query,
 };
 use crate::interceptor::LogIngestInterceptorRef;
 use crate::metrics::http_metrics_layer;
@@ -819,6 +819,7 @@ impl HttpServer {
             .route("/query_range", routing::post(range_query).get(range_query))
             .route("/labels", routing::post(labels_query).get(labels_query))
             .route("/series", routing::post(series_query).get(series_query))
+            .route("/parse_query", routing::post(parse_query).get(parse_query))
             .route(
                 "/label/:label_name/values",
                 routing::get(label_values_query),

src/servers/src/http/prometheus.rs

@@ -101,6 +101,9 @@ pub enum PrometheusResponse {
     LabelValues(Vec<String>),
     FormatQuery(String),
     BuildInfo(OwnedBuildInfo),
+    #[schemars(skip)]
+    #[serde(skip_deserializing)]
+    ParseResult(promql_parser::parser::Expr),
 }
 
 impl Default for PrometheusResponse {
@@ -1014,3 +1017,33 @@ pub async fn series_query(
     resp.resp_metrics = merge_map;
     resp
 }
+
+#[derive(Debug, Default, Serialize, Deserialize, JsonSchema)]
+pub struct ParseQuery {
+    query: Option<String>,
+    db: Option<String>,
+}
+
+#[axum_macros::debug_handler]
+#[tracing::instrument(
+    skip_all,
+    fields(protocol = "prometheus", request_type = "parse_query")
+)]
+pub async fn parse_query(
+    State(_handler): State<PrometheusHandlerRef>,
+    Query(params): Query<ParseQuery>,
+    Extension(_query_ctx): Extension<QueryContext>,
+    Form(form_params): Form<ParseQuery>,
+) -> PrometheusJsonResponse {
+    if let Some(query) = params.query.or(form_params.query) {
+        match promql_parser::parser::parse(&query) {
+            Ok(ast) => PrometheusJsonResponse::success(PrometheusResponse::ParseResult(ast)),
+            Err(err) => {
+                let msg = err.to_string();
+                PrometheusJsonResponse::error(StatusCode::InvalidArguments, msg)
+            }
+        }
+    } else {
+        PrometheusJsonResponse::error(StatusCode::InvalidArguments, "query is required")
+    }
+}

tests-integration/tests/http.rs

@@ -660,6 +660,29 @@ pub async fn test_prom_http_api(store_type: StorageType) {
     let body = serde_json::from_str::<PrometheusJsonResponse>(&res.text().await).unwrap();
     assert_eq!(body.status, "success");
 
+    // parse_query
+    let res = client
+        .get("/v1/prometheus/api/v1/parse_query?query=http_requests")
+        .send()
+        .await;
+    assert_eq!(res.status(), StatusCode::OK);
+    let data = res.text().await;
+    // we don't have deserialization for ast so we keep test simple and compare
+    //  the json output directly.
+    // the correctness should be covered by parser. In this test we only check
+    //  response format.
+    let expected = "{\"status\":\"success\",\"data\":{\"type\":\"vectorSelector\",\"name\":\"http_requests\",\"matchers\":[],\"offset\":0,\"startOrEnd\":null,\"timestamp\":null}}";
+    assert_eq!(expected, data);
+
+    let res = client
+        .get("/v1/prometheus/api/v1/parse_query?query=not http_requests")
+        .send()
+        .await;
+    assert_eq!(res.status(), StatusCode::BAD_REQUEST);
+    let data = res.text().await;
+    let expected = "{\"status\":\"error\",\"data\":{\"resultType\":\"\",\"result\":[]},\"error\":\"invalid promql query\",\"errorType\":\"InvalidArguments\"}";
+    assert_eq!(expected, data);
+
     guard.remove_all().await;
 }