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|
# encoding: UTF-8
require 'base64'
require 'thread'
require 'net/http'
require 'uri'
require 'erb'
require 'set'
require 'prometheus/client'
require 'prometheus/client/formats/text'
require 'prometheus/client/label_set_validator'
module Prometheus
# Client is a ruby implementation for a Prometheus compatible client.
module Client
# Push implements a simple way to transmit a given registry to a given
# Pushgateway.
class Push
class HttpError < StandardError; end
class HttpRedirectError < HttpError; end
class HttpClientError < HttpError; end
class HttpServerError < HttpError; end
DEFAULT_GATEWAY = 'http://localhost:9091'.freeze
PATH = '/metrics/job/%s'.freeze
SUPPORTED_SCHEMES = %w(http https).freeze
attr_reader :job, :gateway, :path
def initialize(job:, gateway: DEFAULT_GATEWAY, grouping_key: {}, **kwargs)
raise ArgumentError, "job cannot be nil" if job.nil?
raise ArgumentError, "job cannot be empty" if job.empty?
@validator = LabelSetValidator.new()
@validator.validate(grouping_key)
@mutex = Mutex.new
@job = job
@gateway = gateway || DEFAULT_GATEWAY
@grouping_key = grouping_key
@path = build_path(job, grouping_key)
@uri = parse("#{@gateway}#{@path}")
validate_no_basic_auth!(@uri)
@http = Net::HTTP.new(@uri.host, @uri.port)
@http.use_ssl = (@uri.scheme == 'https')
@http.open_timeout = kwargs[:open_timeout] if kwargs[:open_timeout]
@http.read_timeout = kwargs[:read_timeout] if kwargs[:read_timeout]
end
def basic_auth(user, password)
@user = user
@password = password
end
def add(registry)
synchronize do
request(Net::HTTP::Post, registry)
end
end
def replace(registry)
synchronize do
request(Net::HTTP::Put, registry)
end
end
def delete
synchronize do
request(Net::HTTP::Delete)
end
end
private
def parse(url)
uri = URI.parse(url)
unless SUPPORTED_SCHEMES.include?(uri.scheme)
raise ArgumentError, 'only HTTP gateway URLs are supported currently.'
end
uri
rescue URI::InvalidURIError => e
raise ArgumentError, "#{url} is not a valid URL: #{e}"
end
def build_path(job, grouping_key)
path = format(PATH, ERB::Util::url_encode(job))
grouping_key.each do |label, value|
if value.include?('/')
encoded_value = Base64.urlsafe_encode64(value)
path += "/#{label}@base64/#{encoded_value}"
# While it's valid for the urlsafe_encode64 function to return an
# empty string when the input string is empty, it doesn't work for
# our specific use case as we're putting the result into a URL path
# segment. A double slash (`//`) can be normalised away by HTTP
# libraries, proxies, and web servers.
#
# For empty strings, we use a single padding character (`=`) as the
# value.
#
# See the pushgateway docs for more details:
#
# https://github.com/prometheus/pushgateway/blob/6393a901f56d4dda62cd0f6ab1f1f07c495b6354/README.md#url
elsif value.empty?
path += "/#{label}@base64/="
else
path += "/#{label}/#{ERB::Util::url_encode(value)}"
end
end
path
end
def request(req_class, registry = nil)
validate_no_label_clashes!(registry) if registry
req = req_class.new(@uri)
req.content_type = Formats::Text::CONTENT_TYPE
req.basic_auth(@user, @password) if @user
req.body = Formats::Text.marshal(registry) if registry
response = @http.request(req)
validate_response!(response)
response
end
def synchronize
@mutex.synchronize { yield }
end
def validate_no_basic_auth!(uri)
if uri.user || uri.password
raise ArgumentError, <<~EOF
Setting Basic Auth credentials in the gateway URL is not supported, please call the `basic_auth` method.
Received username `#{uri.user}` in gateway URL. Instead of passing
Basic Auth credentials like this:
```
push = Prometheus::Client::Push.new(job: "my-job", gateway: "http://user:password@localhost:9091")
```
please pass them like this:
```
push = Prometheus::Client::Push.new(job: "my-job", gateway: "http://localhost:9091")
push.basic_auth("user", "password")
```
While URLs do support passing Basic Auth credentials using the
`http://user:password@example.com/` syntax, the username and
password in that syntax have to follow the usual rules for URL
encoding of characters per RFC 3986
(https://datatracker.ietf.org/doc/html/rfc3986#section-2.1).
Rather than place the burden of correctly performing that encoding
on users of this gem, we decided to have a separate method for
supplying Basic Auth credentials, with no requirement to URL encode
the characters in them.
EOF
end
end
def validate_no_label_clashes!(registry)
# There's nothing to check if we don't have a grouping key
return if @grouping_key.empty?
# We could be doing a lot of comparisons, so let's do them against a
# set rather than an array
grouping_key_labels = @grouping_key.keys.to_set
registry.metrics.each do |metric|
metric.values.keys.first.keys.each do |label|
if grouping_key_labels.include?(label)
raise LabelSetValidator::InvalidLabelSetError,
"label :#{label} from grouping key collides with label of the " \
"same name from metric :#{metric.name} and would overwrite it"
end
end
end
end
def validate_response!(response)
status = Integer(response.code)
if status >= 300
message = "status: #{response.code}, message: #{response.message}, body: #{response.body}"
if status <= 399
raise HttpRedirectError, message
elsif status <= 499
raise HttpClientError, message
else
raise HttpServerError, message
end
end
end
end
end
end
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