Commit 94e6cc52 authored by James Lopez's avatar James Lopez

Merge branch '58839-automatically-set-prometheus-step-interval' into 'master'

Resolve "Automatically set Prometheus step interval"

Closes #58839

See merge request gitlab-org/gitlab-ce!26441
parents c7f918aa 552d3886
---
title: Automatically set Prometheus step interval
merge_request: 26441
author:
type: changed
......@@ -6,6 +6,14 @@ module Gitlab
Error = Class.new(StandardError)
QueryError = Class.new(Gitlab::PrometheusClient::Error)
# Target number of data points for `query_range`.
# Please don't exceed the limit of 11000 data points
# See https://github.com/prometheus/prometheus/blob/91306bdf24f5395e2601773316945a478b4b263d/web/api/v1/api.go#L347
QUERY_RANGE_DATA_POINTS = 600
# Minimal value of the `step` parameter for `query_range` in seconds.
QUERY_RANGE_MIN_STEP = 60
attr_reader :rest_client, :headers
def initialize(rest_client)
......@@ -23,12 +31,18 @@ module Gitlab
end
def query_range(query, start: 8.hours.ago, stop: Time.now)
start = start.to_f
stop = stop.to_f
step = self.class.compute_step(start, stop)
get_result('matrix') do
json_api_get('query_range',
query: query,
start: start.to_f,
end: stop.to_f,
step: 1.minute.to_i)
json_api_get(
'query_range',
query: query,
start: start,
end: stop,
step: step
)
end
end
......@@ -40,6 +54,14 @@ module Gitlab
json_api_get('series', 'match': matches, start: start.to_f, end: stop.to_f)
end
def self.compute_step(start, stop)
diff = stop - start
step = (diff / QUERY_RANGE_DATA_POINTS).ceil
[QUERY_RANGE_MIN_STEP, step].max
end
private
def json_api_get(type, args = {})
......
......@@ -230,4 +230,32 @@ describe Gitlab::PrometheusClient do
let(:execute_query) { subject.query_range(prometheus_query) }
end
end
describe '.compute_step' do
using RSpec::Parameterized::TableSyntax
let(:now) { Time.now.utc }
subject { described_class.compute_step(start, stop) }
where(:time_interval_in_seconds, :step) do
0 | 60
10.hours | 60
10.hours + 1 | 61
# frontend options
30.minutes | 60
3.hours | 60
8.hours | 60
1.day | 144
3.days | 432
1.week | 1008
end
with_them do
let(:start) { now - time_interval_in_seconds }
let(:stop) { now }
it { is_expected.to eq(step) }
end
end
end
......@@ -25,12 +25,16 @@ module PrometheusHelpers
"https://prometheus.example.com/api/v1/query?#{query}"
end
def prometheus_query_range_url(prometheus_query, start: 8.hours.ago, stop: Time.now.to_f)
def prometheus_query_range_url(prometheus_query, start: 8.hours.ago, stop: Time.now, step: nil)
start = start.to_f
stop = stop.to_f
step ||= Gitlab::PrometheusClient.compute_step(start, stop)
query = {
query: prometheus_query,
start: start.to_f,
start: start,
end: stop,
step: 1.minute.to_i
step: step
}.to_query
"https://prometheus.example.com/api/v1/query_range?#{query}"
......
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