Update propagators with composite

CHANGELOG.md

@@ -0,0 +1,29 @@
+# Changelog
+
+## Unreleased
+
+### API
+
+#### Context
+
+- Propagators must now be implementations of a propagator type's behaviour. At
+  this time only the `otel_propagator_text_map` behaviour exists. Callbacks for
+  inject and extract take an optional "set" and "get" function for working with
+  a carrier.
+- Configuration of propagators is now a list of atoms representing either the
+  name of a builtin propagator (at this time those are, `trace_context`, `b3` and
+  `baggage`) or the name of a module implementing the propagator's behaviour.
+  - Default configuration: `{text_map_propagators, [trace_context, baggage]}`
+- Injectors and extractors can be configured separately instead of using the
+  same list of propagators for both by configuring `text_map_injectors` and
+  `text_map_extractors`.
+  - For example you may want your service to support receiving `b3multi` headers
+    but have no need for it including `b3multi` headers when it is propagating to
+    other services:
+
+    ```
+    {text_map_injectors, [trace_context, baggage]},
+    {text_map_extractors, [b3multi, trace_context, baggage]}
+    ```
+- `b3` propagator renamed `b3multi` to properly convey it is the version of the
+  B3 spec that creates multiple headers

apps/opentelemetry/include/otel_span.hrl

@@ -33,7 +33,7 @@
           %% 64 bit int span id
           span_id                 :: opentelemetry:span_id() | undefined,
 
-          tracestate              :: opentelemetry:tracestate() | undefined,
+          tracestate = []         :: opentelemetry:tracestate(),
 
           %% 64 bit int parent span
           parent_span_id          :: opentelemetry:span_id() | undefined,

apps/opentelemetry/src/opentelemetry.app.src

@@ -10,8 +10,7 @@
    ]},
   {env, [{sampler, {parent_based, #{root => always_on}}}, % default sampler
 
-         {text_map_propagators, [fun otel_baggage:get_text_map_propagators/0,
-                                 fun otel_tracer_default:w3c_propagators/0]},
+         {text_map_propagators, [trace_context, baggage]},
 
          %% list of disabled tracers
          {deny_list, []},

apps/opentelemetry/src/opentelemetry_app.erl

@@ -53,16 +53,9 @@ stop(_State) ->
 %% internal functions
 
 setup_text_map_propagators(Opts) ->
-    Propagators = proplists:get_value(text_map_propagators, Opts, []),
-
-    {Extractors, Injectors} =
-        lists:foldl(fun(F, {ExtractorsAcc, InjectorsAcc}) ->
-                            {Extractor, Injector} = F(),
-                            {[Extractor | ExtractorsAcc], [Injector | InjectorsAcc]}
-                    end, {[], []}, Propagators),
-
-    opentelemetry:set_text_map_extractors(Extractors),
-    opentelemetry:set_text_map_injectors(Injectors).
+    List = proplists:get_value(text_map_propagators, Opts, []),
+    CompositePropagator = otel_propagator_text_map_composite:create(List),
+    opentelemetry:set_text_map_propagator(CompositePropagator).
 
 register_loaded_application_tracers(Opts) ->
     RegisterLoadedApplications = proplists:get_value(register_loaded_applications, Opts, true),

apps/opentelemetry/src/otel_configuration.erl

@@ -96,7 +96,7 @@ merge_with_environment(ConfigMappings, Opts) ->
 
 config_mappings(general_sdk) ->
     [{"OTEL_LOG_LEVEL", log_level, "info", existing_atom},
-     {"OTEL_PROPAGATORS", propagators, "tracecontext,baggage", propagators},
+     {"OTEL_PROPAGATORS", text_map_propagators, "tracecontext,baggage", propagators},
      {"OTEL_TRACES_EXPORTER", traces_exporter, "otlp", exporter},
      {"OTEL_METRICS_EXPORTER", metrics_exporter, undefined, exporter}];
 config_mappings(otel_batch_processor) ->
@@ -173,11 +173,16 @@ transform(propagators, PropagatorsString) when is_list(PropagatorsString) ->
                   end, Propagators);
 
 transform(propagator, "tracecontext") ->
-    fun otel_tracer_default:w3c_propagators/0;
-transform(propagator, "b3multi") ->
-    fun otel_tracer_default:b3_propagators/0;
+    trace_context;
 transform(propagator, "baggage") ->
-    fun otel_baggage:get_text_map_propagators/0;
+    baggage;
+transform(propagator, "b3multi") ->
+    b3multi;
+%% TODO: support b3multi and jager propagator formats
+%% transform(propagator, "b3") ->
+%%     b3;
+%% transform(propagator, "jaeger") ->
+%%     jaeger;
 transform(propagator, Propagator) ->
     ?LOG_WARNING("Ignoring uknown propagator ~ts in OS environment variable $OTEL_PROPAGATORS",
                  [Propagator]),

apps/opentelemetry/src/otel_tracer_default.erl

@@ -20,9 +20,8 @@
 -behaviour(otel_tracer).
 
 -export([start_span/4,
-         with_span/5,
-         b3_propagators/0,
-         w3c_propagators/0]).
+         with_span/5
+        ]).
 
 -include_lib("opentelemetry_api/include/opentelemetry.hrl").
 -include("otel_tracer.hrl").
@@ -59,10 +58,3 @@ with_span(Ctx, Tracer, SpanName, Opts, Fun) ->
         otel_ctx:detach(Ctx)
     end.
 
--spec b3_propagators() -> {otel_propagator:text_map_extractor(), otel_propagator:text_map_injector()}.
-b3_propagators() ->
-    otel_tracer:text_map_propagators(otel_propagator_http_b3).
-
--spec w3c_propagators() -> {otel_propagator:text_map_extractor(), otel_propagator:text_map_injector()}.
-w3c_propagators() ->
-    otel_tracer:text_map_propagators(otel_propagator_http_w3c).

apps/opentelemetry/test/opentelemetry_SUITE.erl

@@ -14,20 +14,12 @@
 -include("otel_span_ets.hrl").
 
 all() ->
-    [all_testcases(),
-     {group, w3c},
-     {group, b3}].
-
-all_testcases() ->
     [disable_auto_registration, registered_tracers, with_span, macros, child_spans,
      update_span_data, tracer_instrumentation_library, tracer_previous_ctx, stop_temporary_app,
      reset_after, attach_ctx, default_sampler, non_recording_ets_table, 
      root_span_sampling_always_on, root_span_sampling_always_off, 
-     record_but_not_sample, record_exception_works, record_exception_with_message_works].
-
-groups() ->
-    [{w3c, [], [propagation]},
-     {b3, [], [propagation]}].
+     record_but_not_sample, record_exception_works, record_exception_with_message_works,
+     propagator_configuration, propagator_configuration_with_os_env].
 
 init_per_suite(Config) ->
     application:load(opentelemetry),
@@ -37,30 +29,20 @@ end_per_suite(_Config) ->
     application:unload(opentelemetry),
     ok.
 
-init_per_group(Propagator, Config) when Propagator =:= w3c ;
-                                        Propagator =:= b3 ->
-    application:set_env(opentelemetry, processors, [{otel_batch_processor, #{scheduled_delay_ms => 1}}]),
-    {ok, _} = application:ensure_all_started(opentelemetry),
-
-    {BaggageTextMapExtractor, BaggageTextMapInjector} = otel_baggage:get_text_map_propagators(),
-    {TraceTextMapExtractor, TraceTextMapInjector} = case Propagator of
-                                                        w3c -> otel_tracer_default:w3c_propagators();
-                                                        b3 -> otel_tracer_default:b3_propagators()
-                                                    end,
-    opentelemetry:set_text_map_extractors([BaggageTextMapExtractor,
-                                           TraceTextMapExtractor]),
-    opentelemetry:set_text_map_injectors([BaggageTextMapInjector,
-                                          TraceTextMapInjector]),
-
-    [{propagator, Propagator} | Config].
-
-end_per_group(_, _Config) ->
-    _ = application:stop(opentelemetry).
-
 init_per_testcase(disable_auto_registration, Config) ->
     application:set_env(opentelemetry, register_loaded_applications, false),
     {ok, _} = application:ensure_all_started(opentelemetry),
     Config;
+init_per_testcase(propagator_configuration, Config) ->
+    os:unsetenv("OTEL_PROPAGATORS"),
+    application:set_env(opentelemetry, text_map_propagators, [b3multi, baggage]),
+    {ok, _} = application:ensure_all_started(opentelemetry),
+    Config;
+init_per_testcase(propagator_configuration_with_os_env, Config) ->
+    os:putenv("OTEL_PROPAGATORS", "tracecontext"),
+    application:set_env(opentelemetry, text_map_propagators, [b3multi, baggage]),
+    {ok, _} = application:ensure_all_started(opentelemetry),
+    Config;
 init_per_testcase(_, Config) ->
     application:set_env(opentelemetry, processors, [{otel_batch_processor, #{scheduled_delay_ms => 1}}]),
     {ok, _} = application:ensure_all_started(opentelemetry),
@@ -74,6 +56,10 @@ end_per_testcase(disable_auto_registration, _Config) ->
     _ = application:stop(opentelemetry),
     _ = application:unload(opentelemetry),
     ok;
+end_per_testcase(propagator_configuration_with_os_env, _Config) ->
+    os:unsetenv("OTEL_PROPAGATORS"),
+    _ = application:stop(opentelemetry),
+    ok;
 end_per_testcase(_, _Config) ->
     _ = application:stop(opentelemetry),
     ok.
@@ -94,6 +80,44 @@ registered_tracers(_Config) ->
     ?assertEqual(<<"fake-version">>, NewLibrary#instrumentation_library.version),
     ok.
 
+propagator_configuration(_Config) ->
+    ?assertEqual({otel_propagator_text_map_composite,
+                  [otel_propagator_b3multi, otel_propagator_baggage]}, opentelemetry:get_text_map_extractor()),
+    ?assertEqual({otel_propagator_text_map_composite,
+                  [otel_propagator_b3multi, otel_propagator_baggage]}, opentelemetry:get_text_map_injector()),
+
+    opentelemetry:set_text_map_extractor({otel_propagator_baggage, []}),
+
+    ?assertEqual({otel_propagator_baggage, []}, opentelemetry:get_text_map_extractor()),
+    ?assertEqual({otel_propagator_text_map_composite,
+                  [otel_propagator_b3multi, otel_propagator_baggage]}, opentelemetry:get_text_map_injector()),
+
+    opentelemetry:set_text_map_injector({otel_propagator_b3multi, []}),
+
+    ?assertEqual({otel_propagator_baggage, []}, opentelemetry:get_text_map_extractor()),
+    ?assertEqual({otel_propagator_b3multi, []}, opentelemetry:get_text_map_injector()),
+
+    ok.
+
+propagator_configuration_with_os_env(_Config) ->
+    ?assertEqual({otel_propagator_text_map_composite,
+                  [otel_propagator_trace_context]}, opentelemetry:get_text_map_extractor()),
+    ?assertEqual({otel_propagator_text_map_composite,
+                  [otel_propagator_trace_context]}, opentelemetry:get_text_map_injector()),
+
+    opentelemetry:set_text_map_extractor({otel_propagator_baggage, []}),
+
+    ?assertEqual({otel_propagator_baggage, []}, opentelemetry:get_text_map_extractor()),
+    ?assertEqual({otel_propagator_text_map_composite,
+                  [otel_propagator_trace_context]}, opentelemetry:get_text_map_injector()),
+
+    opentelemetry:set_text_map_injector({otel_propagator_b3multi, []}),
+
+    ?assertEqual({otel_propagator_baggage, []}, opentelemetry:get_text_map_extractor()),
+    ?assertEqual({otel_propagator_b3multi, []}, opentelemetry:get_text_map_injector()),
+
+    ok.
+
 macros(Config) ->
     Tid = ?config(tid, Config),
 
@@ -233,67 +257,6 @@ update_span_data(Config) ->
                                               events=Events,
                                               _='_'})).
 
-propagation(Config) ->
-    Propagator = ?config(propagator, Config),
-    SpanCtx=#span_ctx{trace_id=TraceId,
-                      span_id=SpanId} = ?start_span(<<"span-1">>),
-    ?set_current_span(SpanCtx),
-
-    ?assertMatch(#span_ctx{trace_flags=1}, ?current_span_ctx),
-    ?assertMatch(#span_ctx{is_recording=true}, ?current_span_ctx),
-
-
-    otel_baggage:set("key-1", <<"value=1">>, []),
-    %% TODO: should the whole baggage entry be dropped if metadata is bad?
-    %% drop bad metadata (the `1').
-    otel_baggage:set(<<"key-2">>, <<"value-2">>, [<<"metadata">>, 1, {<<"md-k-1">>, <<"md-v-1">>}]),
-    %% drop baggage with bad value
-    otel_baggage:set(<<"key-3">>, value3),
-
-    Headers = otel_propagator:text_map_inject([{<<"existing-header">>, <<"I exist">>}]),
-
-    EncodedTraceId = io_lib:format("~32.16.0b", [TraceId]),
-    EncodedSpanId = io_lib:format("~16.16.0b", [SpanId]),
-
-    ?assertListsEqual([{<<"baggage">>, <<"key-2=value-2;metadata;md-k-1=md-v-1,key-1=value%3D1">>},
-                       {<<"existing-header">>, <<"I exist">>} |
-                       trace_context(Propagator, EncodedTraceId, EncodedSpanId)], Headers),
-
-    ?end_span(SpanCtx),
-
-    ?assertEqual(#{<<"key-1">> => {<<"value=1">>, []},
-                   <<"key-2">> => {<<"value-2">>, [<<"metadata">>, {<<"md-k-1">>, <<"md-v-1">>}]}},
-                 otel_baggage:get_all()),
-
-    %% ?end_span doesn't remove the span from the context
-    ?assertEqual(SpanCtx, ?current_span_ctx),
-    ?set_current_span(undefined),
-    ?assertEqual(undefined, ?current_span_ctx),
-
-    %% clear our baggage from the context to test extraction
-    otel_baggage:clear(),
-    ?assertEqual(#{}, otel_baggage:get_all()),
-
-    %% make header keys uppercase to validate the extractor is case insensitive
-    BinaryHeaders = [{string:uppercase(Key), iolist_to_binary(Value)} || {Key, Value} <- Headers],
-    otel_propagator:text_map_extract(BinaryHeaders),
-
-    ?assertEqual(#{<<"key-1">> => {<<"value=1">>, []},
-                   <<"key-2">> => {<<"value-2">>, [<<"metadata">>, {<<"md-k-1">>, <<"md-v-1">>}]}},
-                 otel_baggage:get_all()),
-
-    %% extracted remote spans are set to the active span
-    %% but with `is_recording' false
-    ?assertMatch(#span_ctx{is_recording=false}, ?current_span_ctx),
-
-    #span_ctx{trace_id=TraceId2,
-              span_id=_SpanId2} = ?start_span(<<"span-2">>),
-
-    %% new span should be a child of the extracted span
-    ?assertEqual(TraceId, TraceId2),
-
-    ok.
-
 tracer_instrumentation_library(Config) ->
     Tid = ?config(tid, Config),
 
@@ -598,10 +561,3 @@ assert_not_exported(Tid, #span_ctx{trace_id=TraceId,
                                           span_id=SpanId,
                                           _='_'})).
 
-trace_context(w3c, EncodedTraceId, EncodedSpanId) ->
-    [{<<"traceparent">>,
-     iolist_to_binary([<<"00">>, "-", EncodedTraceId,"-", EncodedSpanId, "-", <<"01">>])}];
-trace_context(b3, EncodedTraceId, EncodedSpanId) ->
-    [{<<"X-B3-Sampled">>, <<"1">>},
-     {<<"X-B3-SpanId">>, iolist_to_binary(EncodedSpanId)},
-     {<<"X-B3-TraceId">>, iolist_to_binary(EncodedTraceId)}].

apps/opentelemetry/test/otel_configuration_SUITE.erl

@@ -114,8 +114,7 @@ end_per_testcase(_, Config) ->
 
 empty_os_environment(_Config) ->
     ?assertIsSubset([{log_level,info},
-                     {propagators,[fun otel_tracer_default:w3c_propagators/0,
-                                     fun otel_baggage:get_text_map_propagators/0]},
+                     {text_map_propagators,[trace_context, baggage]},
                      {sampler,{parent_based,#{root => always_on}}}],
                     otel_configuration:merge_with_os([])),
 
@@ -170,14 +169,14 @@ log_level(_Config) ->
 propagators(_Config) ->
     %% TODO: can make this a better error message when it fails with a custom assert macro
     ?assertIsSubset([{log_level, error},
-                     {propagators, [fun otel_baggage:get_text_map_propagators/0]}],
+                     {text_map_propagators, [baggage]}],
                     otel_configuration:merge_with_os([{log_level, error}])),
 
     ok.
 
 propagators_b3multi(_Config) ->
     ?assertIsSubset([{log_level, error},
-                     {propagators, [fun otel_tracer_default:b3_propagators/0]}],
+                     {text_map_propagators, [b3multi]}],
                     otel_configuration:merge_with_os([{log_level, error}])),
 
     ok.