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# frozen_string_literal: true
module Prometheus
class ProxyVariableSubstitutionService < BaseService
include Stepable
steps :validate_variables,
:add_params_to_result,
:substitute_params,
:substitute_ruby_variables,
:substitute_liquid_variables
def initialize(environment, params = {})
@environment, @params = environment, params.deep_dup
end
def execute
execute_steps
end
private
def validate_variables(_result)
return success unless variables
unless variables.is_a?(Array) && variables.size.even?
return error(_('Optional parameter "variables" must be an array of keys and values. Ex: [key1, value1, key2, value2]'))
end
success
end
def add_params_to_result(result)
result[:params] = params
success(result)
end
def substitute_params(result)
start_time = result[:params][:start_time]
end_time = result[:params][:end_time]
result[:params][:start] = start_time if start_time
result[:params][:end] = end_time if end_time
success(result)
end
def substitute_liquid_variables(result)
return success(result) unless query(result)
result[:params][:query] =
TemplateEngines::LiquidService.new(query(result)).render(full_context)
success(result)
rescue TemplateEngines::LiquidService::RenderError => e
error(e.message)
end
def substitute_ruby_variables(result)
return success(result) unless query(result)
# The % operator doesn't replace variables if the hash contains string
# keys.
result[:params][:query] = query(result) % predefined_context.symbolize_keys
success(result)
rescue TypeError, ArgumentError => exception
log_error(exception.message)
Gitlab::ErrorTracking.track_exception(exception, {
template_string: query(result),
variables: predefined_context
})
error(_('Malformed string'))
end
def predefined_context
@predefined_context ||= Gitlab::Prometheus::QueryVariables.call(@environment)
end
def full_context
@full_context ||= predefined_context.reverse_merge(variables_hash)
end
def variables
params[:variables]
end
def variables_hash
# .each_slice(2) converts ['key1', 'value1', 'key2', 'value2'] into
# [['key1', 'value1'], ['key2', 'value2']] which is then converted into
# a hash by to_h: {'key1' => 'value1', 'key2' => 'value2'}
# to_h will raise an ArgumentError if the number of elements in the original
# array is not even.
variables&.each_slice(2).to_h
end
def query(result)
result[:params][:query]
end
end
end
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