Does otlp exporter demo work with collector docker example?

[rerorero]

Sorry for asking a noob question but I'm struggling with making this demo work with the otel collector.

mkdir tmp
cd tmp

git clone [email protected]:open-telemetry/opentelemetry-ruby.git; \ \
    cd opentelemetry-ruby/examples/otel-collector; \
       docker-compose up -d

export OTEL_EXPORTER_OTLP_ENDPOINT=http://0.0.0.0:4318

gem install opentelemetry-sdk
gem install opentelemetry-exporter-otlp

vi main.rb # copy the code from https://github.com/open-telemetry/opentelemetry-ruby/tree/main/exporter/otlp

ruby main.rb

main.rb successfully completed. Then open the zipkin UI with browser: http://localhost:9411/zipkin but I don't see any traces. Am I missing something?

Here is the output of main.rb

ruby main.rb
#<OpenTelemetry::SDK::Trace::Span:0x000000010421c668
 @attributes={},
 @context=
  #<OpenTelemetry::Trace::SpanContext:0x000000010421c690
   @remote=false,
   @span_id="\xBE\xD4\xAF\x1E\xD6\xA4\xE9>",
   @trace_flags=#<OpenTelemetry::Trace::TraceFlags:0x00000001005fcfc0 @flags=1>,
   @trace_id="E<\xEC\x8B\x87@\x9D\xFBw\xCE_?*\xF9\x0F\x93",
   @tracestate=#<OpenTelemetry::Trace::Tracestate:0x00000001005f5068 @hash={}>>,
 @end_timestamp=nil,
 @ended=false,
 @events=nil,
 @instrumentation_library=#<struct OpenTelemetry::SDK::InstrumentationLibrary name="my_app_or_gem", version="0.1.0">,
 @kind=:internal,
 @links=nil,
 @monotonic_start_timestamp=129174327642000,
 @mutex=#<Thread::Mutex:0x000000010421c618>,
 @name="bar",
 @parent_span_id="a\x0E&\xE3\xA4{b|",
 @realtime_start_timestamp=1662651005114950000,
 @resource=
  #<OpenTelemetry::SDK::Resources::Resource:0x00000001006593b0
   @attributes=
    {"service.name"=>"unknown_service",
     "process.pid"=>46894,
     "process.command"=>"main.rb",
     "process.runtime.name"=>"ruby",
     "process.runtime.version"=>"3.1.2",
     "process.runtime.description"=>"ruby 3.1.2p20 (2022-04-12 revision 4491bb740a) [arm64-darwin21]",
     "telemetry.sdk.name"=>"opentelemetry",
     "telemetry.sdk.language"=>"ruby",
     "telemetry.sdk.version"=>"1.1.0"}>,
 @span_limits=
  #<OpenTelemetry::SDK::Trace::SpanLimits:0x00000001005f6968
   @attribute_count_limit=128,
   @attribute_length_limit=nil,
   @event_attribute_count_limit=128,
   @event_count_limit=128,
   @link_attribute_count_limit=128,
   @link_count_limit=128>,
 @span_processors=
  [#<OpenTelemetry::SDK::Trace::Export::BatchSpanProcessor:0x000000010421eff8
    @batch_size=512,
    @condition=#<Thread::ConditionVariable:0x000000010421ebc0>,
    @delay_seconds=5.0,
    @export_mutex=#<Thread::Mutex:0x000000010421ec10>,
    @exporter=
     #<OpenTelemetry::Exporter::OTLP::Exporter:0x0000000100653528
      @compression="gzip",
      @headers={},
      @http=#<Net::HTTP 0.0.0.0:4318 open=false>,
      @metrics_reporter=OpenTelemetry::SDK::Trace::Export::MetricsReporter,
      @path="/v1/traces",
      @shutdown=false,
      @timeout=10.0,
      @uri=#<URI::HTTP http://0.0.0.0:4318/v1/traces>>,
    @exporter_timeout_seconds=30.0,
    @keep_running=true,
    @max_queue_size=2048,
    @metrics_reporter=OpenTelemetry::SDK::Trace::Export::MetricsReporter,
    @mutex=#<Thread::Mutex:0x000000010421ec60>,
    @pid=46894,
    @spans=[],
    @thread=#<Thread:0x000000010421ea30 /Users/rerorero/.rbenv/versions/3.1.2/lib/ruby/gems/3.1.0/gems/opentelemetry-sdk-1.1.0/lib/opentelemetry/sdk/trace/export/batch_span_processor.rb:180 sleep>>],
 @start_timestamp=1662651005114950000,
 @status=#<OpenTelemetry::Trace::Status:0x00000001005c63a8 @code=1, @description="">,
 @total_recorded_attributes=0,
 @total_recorded_events=0,
 @total_recorded_links=0>

[rerorero]

I realized the default span processor exits before the first processing.

opentelemetry-ruby/sdk/lib/opentelemetry/sdk/trace/export/batch_span_processor.rb

Line 49 in b11d8fb

schedule_delay: Float(ENV.fetch('OTEL_BSP_SCHEDULE_DELAY', 5_000)),

I solved this by adding tracer_provider.force_flush to the last line

[arielvalentin]

Nice! I saw that you opened a PR. Thank you very much for your contribution and taking the time out to look into why the demo was not working as expected.