Do not raise when configuration is missing

README.md

@@ -60,7 +60,7 @@ log_level: 1
 Example of environment variables:
 
 ```shell
-# required
+# required (if missing adapter is no-op)
 YABEDA_DATADOG_API_KEY=<your Datadog API key>
 YABEDA_DATADOG_APP_KEY=<your Datadog App key>
 

lib/yabeda/datadog.rb

@@ -14,36 +14,40 @@ module Datadog
     SECOND = 1
     COLLECT_INTERVAL = 60 * SECOND
 
-    # Gem configuration object
-    def self.config
-      @config ||= Config.new
-    end
-
-    # Check the gem configuration has valid state
-    def self.ensure_configured
-      raise ApiKeyError unless config.api_key
-      raise AppKeyError unless config.app_key
-    end
+    class << self
+      # Gem configuration object
+      def config
+        @config ||= Config.new
+      end
 
-    # Prepare the adapter to work
-    def self.start
-      ensure_configured
+      # Check the gem configuration has valid state
+      def ensure_configured
+        raise ApiKeyError unless config.api_key
+        raise AppKeyError unless config.app_key
+      end
 
-      worker = Yabeda::Datadog::Worker.start(config)
-      adapter = Yabeda::Datadog::Adapter.new(worker: worker)
-      Yabeda.register_adapter(:datadog, adapter)
-      adapter
-    end
+      # Prepare the adapter to work
+      def start
+        ensure_configured
+        worker = Yabeda::Datadog::Worker.start(config)
+        adapter = Yabeda::Datadog::Adapter.new(worker: worker)
+        Yabeda.register_adapter(:datadog, adapter)
+        adapter
+      rescue ConfigError => e
+        Logging.instance.warn e.message
+        nil
+      end
 
-    # Start collection metrics from Yabeda collectors
-    def self.start_exporter(collect_interval: COLLECT_INTERVAL)
-      Thread.new do
-        Logging.instance.debug("initilize collectors harvest")
-        loop do
-          Logging.instance.debug("start collectors harvest")
-          Yabeda.collectors.each(&:call)
-          Logging.instance.debug("end collectors harvest")
-          sleep(collect_interval)
+      # Start collection metrics from Yabeda collectors
+      def start_exporter(collect_interval: COLLECT_INTERVAL)
+        Thread.new do
+          Logging.instance.debug("initilize collectors harvest")
+          loop do
+            Logging.instance.debug("start collectors harvest")
+            Yabeda.collectors.each(&:call)
+            Logging.instance.debug("end collectors harvest")
+            sleep(collect_interval)
+          end
         end
       end
     end

lib/yabeda/datadog/exceptions.rb

@@ -2,16 +2,17 @@
 
 module Yabeda
   module Datadog
+    class ConfigError < StandardError; end
     # = This error raised when no Datadog API key provided
-    class ApiKeyError < StandardError
-      def initialize(msg = "Datadog API key doesn't set")
+    class ApiKeyError < ConfigError
+      def initialize(msg = "Datadog API key is missing")
         super
       end
     end
 
     # = This error raised when no Datadog application key provided
-    class AppKeyError < StandardError
-      def initialize(msg = "Datadog application key doesn't set")
+    class AppKeyError < ConfigError
+      def initialize(msg = "Datadog application key is missing")
         super
       end
     end

spec/yabeda/datadog_spec.rb

@@ -9,17 +9,23 @@
     it "requires API key" do
       described_class.config.api_key = nil
       described_class.config.app_key = "qwe"
-      expect do
-        described_class.start
-      end.to raise_error(Yabeda::Datadog::ApiKeyError)
+
+      expect(Yabeda::Datadog::Logging.instance).to receive(:warn).with(/api key is missing/i)
+
+      described_class.start
+
+      expect(Yabeda.adapters[:datadog]).to be_nil
     end
 
     it "requires App key" do
       described_class.config.api_key = "qwe"
       described_class.config.app_key = nil
-      expect do
-        described_class.start
-      end.to raise_error(Yabeda::Datadog::AppKeyError)
+
+      expect(Yabeda::Datadog::Logging.instance).to receive(:warn).with(/application key is missing/i)
+
+      described_class.start
+
+      expect(Yabeda.adapters[:datadog]).to be_nil
     end
   end