diff options
author | Andrew Newdigate <andrew@gitlab.com> | 2019-01-07 13:40:54 +0300 |
---|---|---|
committer | Andrew Newdigate <andrew@gitlab.com> | 2019-01-17 13:32:44 +0300 |
commit | 57a8859a11fe0c2cbd68deb83a2d2857c245fd2f (patch) | |
tree | 26728a2ac8d0dd6937de95e1de0711640de788d7 /lib | |
parent | f383c4032a6b3f2ee2c9e5aa50425fc3a04bc1b4 (diff) |
Conditionally initialize the global opentracing tracer
This change will instantiate an OpenTracing tracer and configure it
as the global tracer when the GITLAB_TRACING environment variable is
configured. GITLAB_TRACING takes a "connection string"-like value,
encapsulating the driver (eg jaeger, etc) and options for the driver.
Since each service, whether it's written in Ruby or Golang, uses the
same connection-string, it should be very easy to configure all
services in a cluster, or even a single development machine to be
setup to use tracing.
Note that this change does not include instrumentation or propagation
changes as this is a way of breaking a previous larger change into
components. The instrumentation and propagation changes will follow
in separate changes.
Diffstat (limited to 'lib')
-rw-r--r-- | lib/gitlab/tracing.rb | 17 | ||||
-rw-r--r-- | lib/gitlab/tracing/factory.rb | 61 | ||||
-rw-r--r-- | lib/gitlab/tracing/jaeger_factory.rb | 97 |
3 files changed, 175 insertions, 0 deletions
diff --git a/lib/gitlab/tracing.rb b/lib/gitlab/tracing.rb new file mode 100644 index 00000000000..3c4db42ac06 --- /dev/null +++ b/lib/gitlab/tracing.rb @@ -0,0 +1,17 @@ +# frozen_string_literal: true + +module Gitlab + module Tracing + # Only enable tracing when the `GITLAB_TRACING` env var is configured. Note that we avoid using ApplicationSettings since + # the same environment variable needs to be configured for Workhorse, Gitaly and any other components which + # emit tracing. Since other components may start before Rails, and may not have access to ApplicationSettings, + # an env var makes more sense. + def self.enabled? + connection_string.present? + end + + def self.connection_string + ENV['GITLAB_TRACING'] + end + end +end diff --git a/lib/gitlab/tracing/factory.rb b/lib/gitlab/tracing/factory.rb new file mode 100644 index 00000000000..fc714164353 --- /dev/null +++ b/lib/gitlab/tracing/factory.rb @@ -0,0 +1,61 @@ +# frozen_string_literal: true + +require "cgi" + +module Gitlab + module Tracing + class Factory + OPENTRACING_SCHEME = "opentracing" + + def self.create_tracer(service_name, connection_string) + return unless connection_string.present? + + begin + opentracing_details = parse_connection_string(connection_string) + driver_name = opentracing_details[:driver_name] + + case driver_name + when "jaeger" + JaegerFactory.create_tracer(service_name, opentracing_details[:options]) + else + raise "Unknown driver: #{driver_name}" + end + rescue => e + # Can't create the tracer? Warn and continue sans tracer + warn "Unable to instantiate tracer: #{e}" + nil + end + end + + def self.parse_connection_string(connection_string) + parsed = URI.parse(connection_string) + + unless valid_uri?(parsed) + raise "Invalid tracing connection string" + end + + { + driver_name: parsed.host, + options: parse_query(parsed.query) + } + end + private_class_method :parse_connection_string + + def self.parse_query(query) + return {} unless query + + CGI.parse(query).symbolize_keys.transform_values(&:first) + end + private_class_method :parse_query + + def self.valid_uri?(uri) + return false unless uri + + uri.scheme == OPENTRACING_SCHEME && + uri.host.to_s =~ /^[a-z0-9_]+$/ && + uri.path.empty? + end + private_class_method :valid_uri? + end + end +end diff --git a/lib/gitlab/tracing/jaeger_factory.rb b/lib/gitlab/tracing/jaeger_factory.rb new file mode 100644 index 00000000000..0726f6b67f4 --- /dev/null +++ b/lib/gitlab/tracing/jaeger_factory.rb @@ -0,0 +1,97 @@ +# frozen_string_literal: true + +require 'jaeger/client' + +module Gitlab + module Tracing + class JaegerFactory + # When the probabilistic sampler is used, by default 0.1% of requests will be traced + DEFAULT_PROBABILISTIC_RATE = 0.001 + + # The default port for the Jaeger agent UDP listener + DEFAULT_UDP_PORT = 6831 + + # Reduce this from default of 10 seconds as the Ruby jaeger + # client doesn't have overflow control, leading to very large + # messages which fail to send over UDP (max packet = 64k) + # Flush more often, with smaller packets + FLUSH_INTERVAL = 5 + + def self.create_tracer(service_name, options) + kwargs = { + service_name: service_name, + sampler: get_sampler(options[:sampler], options[:sampler_param]), + reporter: get_reporter(service_name, options[:http_endpoint], options[:udp_endpoint]) + } + + extra_params = options.except(:sampler, :sampler_param, :http_endpoint, :udp_endpoint, :strict_parsing, :debug) # rubocop: disable CodeReuse/ActiveRecord + if extra_params.present? + message = "jaeger tracer: invalid option: #{extra_params.keys.join(", ")}" + + if options[:strict_parsing] + raise message + else + warn message + end + end + + Jaeger::Client.build(kwargs) + end + + def self.get_sampler(sampler_type, sampler_param) + case sampler_type + when "probabilistic" + sampler_rate = sampler_param ? sampler_param.to_f : DEFAULT_PROBABILISTIC_RATE + Jaeger::Samplers::Probabilistic.new(rate: sampler_rate) + when "const" + const_value = sampler_param == "1" + Jaeger::Samplers::Const.new(const_value) + else + nil + end + end + private_class_method :get_sampler + + def self.get_reporter(service_name, http_endpoint, udp_endpoint) + encoder = Jaeger::Encoders::ThriftEncoder.new(service_name: service_name) + + if http_endpoint.present? + sender = get_http_sender(encoder, http_endpoint) + elsif udp_endpoint.present? + sender = get_udp_sender(encoder, udp_endpoint) + else + return nil + end + + Jaeger::Reporters::RemoteReporter.new( + sender: sender, + flush_interval: FLUSH_INTERVAL + ) + end + private_class_method :get_reporter + + def self.get_http_sender(encoder, address) + Jaeger::HttpSender.new( + url: address, + encoder: encoder, + logger: Logger.new(STDOUT) + ) + end + private_class_method :get_http_sender + + def self.get_udp_sender(encoder, address) + pair = address.split(":", 2) + host = pair[0] + port = pair[1] ? pair[1].to_i : DEFAULT_UDP_PORT + + Jaeger::UdpSender.new( + host: host, + port: port, + encoder: encoder, + logger: Logger.new(STDOUT) + ) + end + private_class_method :get_udp_sender + end + end +end |