Add tag(s) DNS lookup time out.

.gitignore

@@ -2,3 +2,4 @@
 Gemfile.lock
 .bundle
 vendor
+.idea

CHANGELOG.md

@@ -1,3 +1,7 @@
+## 3.2.0
+  - Support adding tag(s) on DNS lookup times out, defaults to `["_dnstimeout"]` [#67](https://github.com/logstash-plugins/logstash-filter-dns/pull/67)
+  - As timeouts can be received through tags now, DNS lookup timeouts are logged in debug logs only. [#67](https://github.com/logstash-plugins/logstash-filter-dns/pull/67)
+
 ## 3.1.5
   - Fixed an issue where a non-string value existing in the resolve/reverse field could cause the plugin to crash [#65](https://github.com/logstash-plugins/logstash-filter-dns/pull/65)
 

docs/index.asciidoc

@@ -58,6 +58,7 @@ This plugin supports the following configuration options plus the <<plugins-{typ
 | <<plugins-{type}s-{plugin}-nameserver>> |<<hash,hash>>|No
 | <<plugins-{type}s-{plugin}-resolve>> |<<array,array>>|No
 | <<plugins-{type}s-{plugin}-reverse>> |<<array,array>>|No
+| <<plugins-{type}s-{plugin}-tag_on_timeout>> |<<array,array>>|No
 | <<plugins-{type}s-{plugin}-timeout>> |<<number,number>>|No
 |=======================================================================
 
@@ -173,6 +174,13 @@ Reverse resolve one or more fields.
 
 `resolv` calls will be wrapped in a timeout instance
 
+[id="plugins-{type}s-{plugin}-tag_on_timeout"]
+===== `tag_on_timeout`
+
+* Value type is <<array,array>>
+* Defaults to `["_dnstimeout"]`.
+
+Add tag(s) on DNS lookup time out.
 
 
 [id="plugins-{type}s-{plugin}-common-options"]

lib/logstash/filters/dns.rb

@@ -86,6 +86,9 @@ class LogStash::Filters::DNS < LogStash::Filters::Base
   # Use custom hosts file(s). For example: `["/var/db/my_custom_hosts"]`
   config :hostsfile, :validate => :array
 
+  # Tag(s) to apply if a DNS lookup times out. Defaults to `["_dnstimeout"]`.
+  config :tag_on_timeout, :validate => :string, :list => true, :default => ["_dnstimeout"]
+
   attr_reader :hit_cache
   attr_reader :failed_cache
 
@@ -219,8 +222,9 @@ def resolve(event)
         end
       rescue Resolv::ResolvTimeout
         @failed_cache[raw] = true if @failed_cache
-        @logger.warn("DNS: timeout on resolving the hostname.",
+        @logger.debug("DNS: timeout on resolving the hostname.",
                       :field => field, :value => raw)
+        @tag_on_timeout.each { |tag| event.tag(tag) }
         return
       rescue SocketError => e
         @logger.error("DNS: Encountered SocketError.",
@@ -305,8 +309,9 @@ def reverse(event)
         end
       rescue Resolv::ResolvTimeout
         @failed_cache[raw] = true if @failed_cache
-        @logger.warn("DNS: timeout on resolving address.",
+        @logger.debug("DNS: timeout on resolving address.",
                       :field => field, :value => raw)
+        @tag_on_timeout.each { |tag| event.tag(tag) }
         return
       rescue SocketError => e
         @logger.error("DNS: Encountered SocketError.",
@@ -345,7 +350,7 @@ def retriable_request(&block)
     tries = 0
     begin
       block.call
-    rescue Resolv::ResolvTimeout,  SocketError
+    rescue Resolv::ResolvTimeout, SocketError
       if tries < @max_retries
         tries = tries + 1
         retry

logstash-filter-dns.gemspec

@@ -1,7 +1,7 @@
 Gem::Specification.new do |s|
 
   s.name            = 'logstash-filter-dns'
-  s.version         = '3.1.5'
+  s.version         = '3.2.0'
   s.licenses        = ['Apache License (2.0)']
   s.summary         = "Performs a standard or reverse DNS lookup"
   s.description     = "This gem is a Logstash plugin required to be installed on top of the Logstash core pipeline using $LS_HOME/bin/logstash-plugin install gemname. This gem is not a stand-alone program"

spec/filters/dns_spec.rb

@@ -7,6 +7,7 @@
 
 
 describe LogStash::Filters::DNS do
+
   describe "with stubbed Resolv" do
     before(:each) do
       # We use `Resolv#each_address` and `Resolv#each_name`, which have
@@ -621,4 +622,115 @@
       end
     end
   end
+
+  describe "dns forward timeout" do
+
+    let(:subject) { LogStash::Filters::DNS.new(config) }
+
+    before(:each) do
+      allow(subject).to receive(:getaddress).and_raise(Resolv::ResolvTimeout)
+      subject.register
+      subject.filter(event)
+    end
+
+    context "when using the default tag" do
+      let(:config) { { "resolve" => ["message"] } }
+      let(:event) { LogStash::Event.new("message" => "carrera.databits.net") }
+
+      it "should add the default DNS timeout tag" do
+        expect(event.get("tags")).to eq(["_dnstimeout"])
+      end
+    end
+
+    context "when using a custom tag" do
+      let(:config) { { "resolve" => ["message"], "tag_on_timeout" => ["dns_custom_timeout"] } }
+      let(:event) { LogStash::Event.new("message" => "carrera.databits.net") }
+
+      it "should add the custom DNS timeout tag" do
+        expect(event.get("tags")).to eq(["dns_custom_timeout"])
+      end
+    end
+
+    context "when using no tags" do
+      let(:config) { { "resolve" => ["message"], "tag_on_timeout" => [] } }
+      let(:event) { LogStash::Event.new("message" => "carrera.databits.net") }
+
+      it "should not add any failure tags" do
+        expect(event.get("tags")).to eq(nil)
+      end
+    end
+
+    context "when logging" do
+
+      context "with debug" do
+        let(:config) { { "resolve" => ["message"] } }
+        let(:event) { LogStash::Event.new("message" => "127.0.0.1") }
+
+        before do
+          allow(subject.logger).to receive(:debug).with(any_args)
+        end
+
+        it "logs on timeout exception" do
+          subject.filter(event)
+          expect(subject.logger).to have_received(:debug).with("DNS: timeout on resolving the hostname.", :field => "message", :value => "127.0.0.1")
+        end
+      end
+    end
+  end
+
+  describe "dns reverse timeout" do
+
+    let(:subject) { LogStash::Filters::DNS.new(config) }
+
+    before(:each) do
+      allow(subject).to receive(:getname).and_raise(Resolv::ResolvTimeout)
+      subject.register
+      subject.filter(event)
+    end
+
+    context "when using the default tag" do
+      let(:config) { { "reverse" => ["message"] } }
+      let(:event) { LogStash::Event.new("message" => "127.0.0.1") }
+
+      it "should add the default DNS timeout tag" do
+        expect(event.get("tags")).to eq(["_dnstimeout"])
+      end
+    end
+
+    context "when using a custom tag" do
+      let(:config) { { "reverse" => ["message"], "tag_on_timeout" => ["dns_custom_timeout"] } }
+      let(:event) { LogStash::Event.new("message" => "127.0.0.1") }
+
+      it "should add the custom DNS timeout tag" do
+        expect(event.get("tags")).to eq(["dns_custom_timeout"])
+      end
+    end
+
+    context "when using no tags" do
+      let(:config) { { "reverse" => ["message"], "tag_on_timeout" => [] } }
+      let(:event) { LogStash::Event.new("message" => "127.0.0.1") }
+
+      it "should not add any failure tags" do
+        expect(event.get("tags")).to eq(nil)
+      end
+    end
+
+    context "when logging" do
+
+      context "with debug" do
+        let(:config) { { "reverse" => ["message"] } }
+        let(:event) { LogStash::Event.new("message" => "127.0.0.1") }
+
+        before do
+          allow(subject.logger).to receive(:debug).with(any_args)
+        end
+
+        it "logs timeout exception" do
+          subject.filter(event)
+          expect(subject.logger).to have_received(:debug).with("DNS: timeout on resolving address.", :field => "message", :value => "127.0.0.1")
+        end
+      end
+    end
+  end
+
 end