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# frozen_string_literal: true
#
# Author:: Tim Smith (<tsmith@chef.io>)
# Copyright:: Copyright (c) Chef Software Inc.
# License:: Apache License, Version 2.0
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
require "net/http" unless defined?(Net::HTTP)
module Ohai
module Mixin
#
# This code parses the Azure Instance Metadata API to provide details
# of the running instance.
#
# The code probes the instance metadata endpoint for
# available versions, determines the most advanced version known to
# work and executes the metadata retrieval using that version.
#
# If no compatible version is found, an empty hash is returned.
#
module AzureMetadata
AZURE_METADATA_ADDR ||= "169.254.169.254"
# it's important that the newer versions are at the end of this array so we can skip sorting it
AZURE_SUPPORTED_VERSIONS ||= %w{ 2018-10-01 2019-02-01 2019-03-11 2019-04-30 2019-06-01
2019-06-04 2019-08-01 2019-08-15 2019-11-01 2020-06-01
2020-07-15 2020-09-01 2020-10-01 2020-12-01 2021-01-01
2021-02-01 2021-03-01 2021-05-01 2021-10-01 }.freeze
def best_api_version
@api_version ||= begin
logger.trace("Mixin AzureMetadata: Fetching http://#{AZURE_METADATA_ADDR}/metadata/instance to determine the latest supported metadata release")
response = http_get("/metadata/instance")
if response.code == "404"
logger.trace("Mixin AzureMetadata: Received HTTP 404 from metadata server while determining API version, assuming #{AZURE_SUPPORTED_VERSIONS.last}")
return AZURE_SUPPORTED_VERSIONS.last
elsif response.code != "400" # 400 is actually what we want
raise "Mixin AzureMetadata: Unable to determine Azure metadata version (returned #{response.code} response)"
end
# azure returns a list of the 3 latest versions it supports
versions = parse_json(response.body).fetch("newest-versions", [])
versions.sort!
until versions.empty? || AZURE_SUPPORTED_VERSIONS.include?(versions.last)
pv = versions.pop
logger.trace("Mixin AzureMetadata: Azure metadata version #{pv} is not present in the versions provided by the Azure Instance Metadata service")
end
if versions.empty?
logger.debug "Mixin AzureMetadata: The short list of supported versions provided by Azure Instance Metadata service doesn't match any known versions to Ohai. Using the latest supported release known to Ohai instead: #{AZURE_SUPPORTED_VERSIONS.last}"
return AZURE_SUPPORTED_VERSIONS.last
end
logger.trace("Mixin AzureMetadata: Latest supported Azure metadata version: #{versions.last}")
versions.last
end
end
# fetch the meta content with a timeout and the required header and a read timeout of 6s
#
# @param [String] the relative uri to fetch from the Azure Metadata Service URL
#
# @return [Net::HTTP]
def http_get(uri)
conn = Net::HTTP.start(AZURE_METADATA_ADDR)
conn.read_timeout = 6
conn.get(uri, { "Metadata" => "true" })
end
# parse JSON data from a String to a Hash
#
# @param [String] response_body json as string to parse
#
# @return [Hash]
def parse_json(response_body)
data = String(response_body)
parser = FFI_Yajl::Parser.new
parser.parse(data)
rescue FFI_Yajl::ParseError
logger.warn("Mixin AzureMetadata: Metadata response is NOT valid JSON")
nil
end
def fetch_metadata(api_version = nil)
metadata_url = "/metadata/instance?api-version=#{best_api_version}"
logger.trace("Mixin AzureMetadata: Fetching metadata from host #{AZURE_METADATA_ADDR} at #{metadata_url}")
response = http_get(metadata_url)
if response.code == "200"
parse_json(response.body)
else
logger.warn("Mixin AzureMetadata: Received response code #{response.code} requesting metadata")
nil
end
end
end
end
end
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