functions

Prometheus functions can be built by name. For example:

from pangolier.functions import function

abs = function('abs')
print(abs(
    Metric('http_requests_total')
).to_str(pretty=True))

output:

abs(
    http_requests_total
)

range_function should be used for functions accept a range-vector.

from pangolier.functions import range_function

rate = range_function('rate')
print(rate(
    Metric('http_requests_total'),
    timespan='5m'
).to_str(pretty=True))

output:

rate(
    http_requests_total[5m]
)

aggregation_operator shoule be used for aggregation operators:

from pangolier.functions import aggregation_operator

sum_ = aggregation_operator('sum')
print(sum_(
    Metric('http_requests_total'),
    by=['job', 'group'],
).to_str(pretty=True))

output:

sum by(
    job, group
)(
    http_requests_total
)

combine them all together:

histogram_quantile = function('histogram_quantile')
rate = range_function('rate')
sum_ = aggregation_operator('sum')

print(histogram_quantile(
    0.9,
    sum_(
        rate(
            Metric('http_request_duration_seconds_bucket'),
            timespan='5m',
        ),
        by=['le']
    )
).to_str(pretty=True))

output:

histogram_quantile(
    0.9,
    sum by(
        le
    )(
        rate(
            http_request_duration_seconds_bucket[5m]
        )
    )
)