PromQL.NET

PromQL has two basic types of data on which you can select and aggregate time series data in real time.

So were going to talk about instant vector and range vector.

Example #1:

Create InstantVector and apply "sum" aggregation operator on it: https://prometheus.io/docs/prometheus/latest/querying/operators/#aggregation-operators

var query = InstantVector
    .WithString("http_requests_total")
    .Sum();

Console.WriteLine(query);
// OUTPUT: sum(http_requests_total)

Example #2:

For now were using RangeVector instead of InstantVector, selecting http requests count per instance, and sorting it in descending order:

var query = RangeVector
    .WithString("http_requests_total", TimeSpan.FromSeconds(15))
    .SumOverTime()  // Same "sum" aggregation operator as in InstantVector, but applies to RangeVector and returns as result InstantVector (!) instead of RangeVector
    .SumWithFilter(
        LabelFilter.Create()
            .WithType(LabelFilterType.By)
            .AddField("instance"))
    .SortDescending();

Console.WriteLine(query);
// OUTPUT: sort_desc(sum by (instance) (sum_over_time(http_requests_total[15s])))

Our goal is to make everything to work as expected and prevent wrong syntax in generated prometheus queries.