103 lines
2.8 KiB
Ruby
103 lines
2.8 KiB
Ruby
# frozen_string_literal: true
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module Prometheus
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class ProxyVariableSubstitutionService < BaseService
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include Stepable
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VARIABLE_INTERPOLATION_REGEX = /
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{{ # Variable needs to be wrapped in these chars.
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\s* # Allow whitespace before and after the variable name.
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(?<variable> # Named capture.
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\w+ # Match one or more word characters.
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)
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\s*
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}}
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/x.freeze
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steps :validate_variables,
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:add_params_to_result,
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:substitute_params,
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:substitute_variables
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def initialize(environment, params = {})
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@environment, @params = environment, params.deep_dup
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end
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def execute
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execute_steps
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end
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private
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def validate_variables(_result)
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return success unless variables
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unless variables.is_a?(Array) && variables.size.even?
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return error(_('Optional parameter "variables" must be an array of keys and values. Ex: [key1, value1, key2, value2]'))
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end
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success
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end
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def add_params_to_result(result)
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result[:params] = params
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success(result)
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end
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def substitute_params(result)
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start_time = result[:params][:start_time]
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end_time = result[:params][:end_time]
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result[:params][:start] = start_time if start_time
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result[:params][:end] = end_time if end_time
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success(result)
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end
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def substitute_variables(result)
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return success(result) unless query(result)
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result[:params][:query] = gsub(query(result), full_context)
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success(result)
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end
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def gsub(string, context)
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# Search for variables of the form `{{variable}}` in the string and replace
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# them with their value.
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string.gsub(VARIABLE_INTERPOLATION_REGEX) do |match|
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# Replace with the value of the variable, or if there is no such variable,
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# replace the invalid variable with itself. So,
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# `up{instance="{{invalid_variable}}"}` will remain
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# `up{instance="{{invalid_variable}}"}` after substitution.
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context.fetch($~[:variable], match)
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end
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end
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def predefined_context
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Gitlab::Prometheus::QueryVariables.call(@environment).stringify_keys
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end
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def full_context
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@full_context ||= predefined_context.reverse_merge(variables_hash)
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end
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def variables
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params[:variables]
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end
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def variables_hash
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# .each_slice(2) converts ['key1', 'value1', 'key2', 'value2'] into
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# [['key1', 'value1'], ['key2', 'value2']] which is then converted into
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# a hash by to_h: {'key1' => 'value1', 'key2' => 'value2'}
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# to_h will raise an ArgumentError if the number of elements in the original
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# array is not even.
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variables&.each_slice(2).to_h
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end
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def query(result)
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result[:params][:query]
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end
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end
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end
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