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# frozen_string_literal: true
module Gitlab
# Helper methods to interact with Prometheus network services & resources
class PrometheusClient
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)
@rest_client = rest_client
end
def ping
json_api_get('query', query: '1')
end
def query(query, time: Time.now)
get_result('vector') do
json_api_get('query', query: query, time: time.to_f)
end
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,
end: stop,
step: step
)
end
end
def label_values(name = '__name__')
json_api_get("label/#{name}/values")
end
def series(*matches, start: 8.hours.ago, stop: Time.now)
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 = {})
path = ['api', 'v1', type].join('/')
get(path, args)
rescue JSON::ParserError
raise PrometheusClient::Error, 'Parsing response failed'
rescue Errno::ECONNREFUSED
raise PrometheusClient::Error, 'Connection refused'
end
def get(path, args)
response = rest_client[path].get(params: args)
handle_response(response)
rescue SocketError
raise PrometheusClient::Error, "Can't connect to #{rest_client.url}"
rescue OpenSSL::SSL::SSLError
raise PrometheusClient::Error, "#{rest_client.url} contains invalid SSL data"
rescue RestClient::ExceptionWithResponse => ex
if ex.response
handle_exception_response(ex.response)
else
raise PrometheusClient::Error, "Network connection error"
end
rescue RestClient::Exception
raise PrometheusClient::Error, "Network connection error"
end
def handle_response(response)
json_data = JSON.parse(response.body)
if response.code == 200 && json_data['status'] == 'success'
json_data['data'] || {}
else
raise PrometheusClient::Error, "#{response.code} - #{response.body}"
end
end
def handle_exception_response(response)
if response.code == 200 && response['status'] == 'success'
response['data'] || {}
elsif response.code == 400
json_data = JSON.parse(response.body)
raise PrometheusClient::QueryError, json_data['error'] || 'Bad data received'
else
raise PrometheusClient::Error, "#{response.code} - #{response.body}"
end
end
def get_result(expected_type)
data = yield
data['result'] if data['resultType'] == expected_type
end
end
end
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