mquery

mquery, short for (M)etrics Query, is a Rust library for handling PROMQL (and possibly MetricsQL) queries.

The library internally uses prometheus-http-query crate. As the name suggests, mquery is mainly focused on dealing with metrics queries and the resulting data, and nothing else. The aforementioned library is better suited when functionality related to the full HTTP API offered by Prometheus and other compatible solutions is required.

The library supports raw queries (strings) as well as typed queries (builder API). The builder API is provided through the type Metric and Scalar types found in the query module. Note that the builder API doesn't prevent you from writing invalid queries, it only helps you avoid errors to a certain degree.

Any additional utilities related to handling and processing the query data can be found in the utils module which is placed under the utils feature flag.

A compile time query validation like the one found in the sqlx crate is on the roadmap.

Usage Example

use mquery::{Auth, QueryManager, query};

#[tokio::main]
async fn main() {
    dotenv::dotenv().expect("No .env file found in working dir");
    let url = std::env::var("VM_URL").expect("VM URL not found in env");
    let token = std::env::var("VM_TOKEN").expect("VM token not found in env");

    let query = query::Metric::new("total_http_requests").label_eq("method", "get");

    let _response = QueryManager::new(url.parse().unwrap())
                      .auth(Auth::Bearer(token))
                      .query(query)
                      .await
                      .expect("operation failed");
}

Debugging

When you keep getting the error Client(ClientError("failed to parse response from server due to invalid media type")) and cannot figure out what might be wrong, it is likely that the server URL is the culprit. Ensure that only the base URL to the server is passed to the QueryManager which shouldn't contain the API endpoint path like /api/v1/query.

Testing

Requires a local Victoria Metrics server running at http://127.0.0.1:8428/ for the integration tests to work.

Roadmap

• Basic raw queries (Instant and Ranged)
• Query Builder
  • Basic queries
  • Operators
    • Binary Operators
    • Vector matching
    • Aggregation operators
  • Functions
• Runtime syntax checking
• Compile time syntax checking
• Deserialize Convert to custom data types
• ORM-like API to build queries using user defined types (derive macro)
• Encapsulated raw queries with methods for constructing interpolated versions
• Processing multiple queries at once