docker/syslog: fluend plugins

Author: hanazuki

fluentd/Dockerfile

@@ -1,8 +1,6 @@
 FROM fluent/fluentd:v1.15-debian-1
 
 USER root
-RUN fluent-gem install fluent-plugin-prometheus -v 2.0.3
-
-USER fluent
-
-EXPOSE 24231
+RUN fluent-gem install fluent-plugin-prometheus -v 2.0.3 && \
+    fluent-gem install fluent-plugin-s3 -v 1.7.1
+COPY ./plugins/ /fluentd/plugins/

fluentd/plugins/in_http_healthcheck.rb

@@ -0,0 +1,41 @@
+module Fluent::Plugin
+  class HttpHealthCheckInput < Input
+    Fluent::Plugin.register_input('http_healthcheck', self)
+    helpers :http_server
+
+    desc 'The address to bind to.'
+    config_param :bind, :string, default: '0.0.0.0'
+    desc 'The port to listen to.'
+    config_param :port, :integer, default: 8080
+
+    CONTENT_TYPE_TEXT_PLAIN = { 'Content-Type' => 'text/plain' }.freeze
+
+    def start
+      super
+
+      log.info "healthcheck endpoint at http://#{@bind}:#{@port}/healthz"
+
+      http_server_create_http_server(
+        :in_http_healthcheck_helper,
+        addr: @bind,
+        port: @port,
+        logger: log,
+      ) do |serv|
+        serv.get('/healthz') do
+          if healthy?
+            [200, CONTENT_TYPE_TEXT_PLAIN, ['ok']]
+          else
+            [500, CONTENT_TYPE_TEXT_PLAIN, ['not ok']]
+          end
+        end
+      end
+    end
+
+    private
+
+    def healthy?
+      # TODO: check workers in multi-worker mode
+      true
+    end
+  end
+end