Add option for Mongo span resource as JSON

Author: marcotc

Matrixfile

@@ -121,7 +121,7 @@
   },
   'mongodb' => {
     'mongo-latest' => '✅ 2.5 / ✅ 2.6 / ✅ 2.7 / ✅ 3.0 / ✅ 3.1 / ✅ 3.2 / ✅ 3.3 / ✅ 3.4 / ✅ jruby',
-    # 'mongo-min'    => '✅ 2.5 / ✅ 2.6 / ✅ 2.7 / ✅ 3.0 / ✅ 3.1 / ✅ 3.2 / ✅ 3.3 / ✅ 3.4 / ✅ jruby',
+    'mongo-min'    => '✅ 2.5 / ✅ 2.6 / ✅ 2.7 / ✅ 3.0 / ✅ 3.1 / ✅ 3.2 / ✅ 3.3 / ✅ 3.4 / ✅ jruby',
   },
   'mysql2' => {
     'relational_db' => '✅ 2.5 / ✅ 2.6 / ✅ 2.7 / ✅ 3.0 / ✅ 3.1 / ✅ 3.2 / ✅ 3.3 / ✅ 3.4 / ❌ jruby'

docs/GettingStarted.md

@@ -1144,7 +1144,7 @@ require 'mongo'
 require 'datadog'
 
 Datadog.configure do |c|
-  c.tracing.instrument :mongo, **options
+  c.tracing.instrument :mongo, json_command: true, **options
 end
 
 # Create a MongoDB client and use it as usual
@@ -1164,6 +1164,7 @@ Datadog.configure_onto(client, **options)
 | `service_name` | `DD_TRACE_MONGO_SERVICE_NAME` | `String` | Name of application running the `mongo` instrumentation. May be overridden by `global_default_service_name`. [See _Additional Configuration_ for more details](#additional-configuration)   | `mongodb`                                        |
 | `peer_service` | `DD_TRACE_MONGO_PEER_SERVICE` | `String` | Name of external service the application connects to                                                                                                                                        | `nil`                                            |
 | `quantize`     |                               | `Hash`   | Hash containing options for quantization. May include `:show` with an Array of keys to not quantize (or `:all` to skip quantization), or `:exclude` with Array of keys to exclude entirely. | `{ show: [:collection, :database, :operation] }` |
+| `json_command` | `DD_TRACE_MONGO_JSON_COMMAND` | `Bool` | (Recommended) Serialize the MongoDB command as JSON, which enables full support for introspection in the Datadog App. | `false` |
 
 **Configuring trace settings per connection**
 

lib/datadog/tracing/contrib/mongodb/configuration/settings.rb

@@ -48,6 +48,14 @@ class Settings < Contrib::Configuration::Settings
               o.type :string, nilable: true
               o.env Ext::ENV_PEER_SERVICE
             end
+
+            # Serializes the command to JSON format, which is the desired format for the agent and Datadog UI.
+            # Setting this to false is deprecated and does not have any advantages.
+            option :json_command do |o|
+              o.type :bool
+              o.env Ext::ENV_JSON_COMMAND
+              o.default false
+            end
           end
         end
       end

lib/datadog/tracing/contrib/mongodb/ext.rb

@@ -13,6 +13,7 @@ module Ext
           # @!visibility private
           ENV_ANALYTICS_ENABLED = 'DD_TRACE_MONGO_ANALYTICS_ENABLED'
           ENV_ANALYTICS_SAMPLE_RATE = 'DD_TRACE_MONGO_ANALYTICS_SAMPLE_RATE'
+          ENV_JSON_COMMAND = 'DD_TRACE_MONGO_JSON_COMMAND'
           DEFAULT_PEER_SERVICE_NAME = 'mongodb'
           SPAN_COMMAND = 'mongo.cmd'
           SPAN_TYPE_COMMAND = 'mongodb'

lib/datadog/tracing/contrib/mongodb/subscribers.rb

@@ -1,5 +1,7 @@
 # frozen_string_literal: true
 
+require 'json'
+
 require_relative '../analytics'
 require_relative 'ext'
 require_relative '../ext'
@@ -30,7 +32,7 @@ def started(event)
 
             # build a quantized Query using the Parser module
             query = MongoDB.query_builder(event.command_name, event.database_name, event.command)
-            serialized_query = query.to_s
+            serialized_query = serialize_query(query)
 
             if datadog_configuration[:peer_service]
               span.set_tag(
@@ -109,6 +111,21 @@ def succeeded(event)
 
           private
 
+          def serialize_query(query)
+            if datadog_configuration[:json_command]
+              query.to_json
+            else
+              # Incorrect Hash#to_s serialization. The Mongo command should only be encoded as JSON.
+              # This code path should be removed, and is only kept to avoid a breaking change.
+              Datadog::Core.log_deprecation(key: :mongo_json_command) do
+                'MongoDB integration: `json_command: false` causes invalid command serialization. '\
+                'Use `json_command: true` or `DD_TRACE_MONGO_JSON_COMMAND=1` instead.'
+              end
+
+              query.to_s
+            end
+          end
+
           def get_span(event)
             Thread.current[:datadog_mongo_span] \
               && Thread.current[:datadog_mongo_span][event.request_id]

sig/datadog/tracing/contrib/mongodb/ext.rbs

@@ -5,6 +5,7 @@ module Datadog
         module Ext
           ENV_ENABLED: "DD_TRACE_MONGO_ENABLED"
 
+          ENV_JSON_COMMAND: "DD_TRACE_MONGO_JSON_COMMAND"
           ENV_PEER_SERVICE: "DD_TRACE_MONGO_PEER_SERVICE"
           ENV_SERVICE_NAME: "DD_TRACE_MONGO_SERVICE_NAME"
 

sig/datadog/tracing/contrib/mongodb/parsers.rbs

@@ -8,7 +8,7 @@ module Datadog
 
         DEFAULT_OPTIONS: { exclude: untyped, show: untyped }
         PLACEHOLDER: "?"
-        def self?.query_builder: (untyped command_name, untyped database_name, untyped command) -> untyped
+        def self?.query_builder: (untyped command_name, untyped database_name, untyped command) -> Hash[untyped, untyped]
 
         def self?.quantization_options: () -> untyped
 

sig/datadog/tracing/contrib/mongodb/subscribers.rbs

@@ -13,6 +13,8 @@ module Datadog
 
           def get_span: (untyped event) -> untyped
 
+          def serialize_query: (Hash[untyped, untyped] query) -> string
+
           def set_span: (untyped event, untyped span) -> untyped
 
           def clear_span: (untyped event) -> (nil | untyped)