Fix error messages from docker facts if docker not running (#325)

Author: stdietrich

lib/facter/docker.rb

@@ -21,7 +21,11 @@ def interfaces
 Facter.add(:docker_server_version) do
   setcode do
     docker_version = Facter.value(:docker_version)
-    docker_version['Server']['Version'] if docker_version
+    if docker_version && docker_version['Server'].is_a?(Hash)
+      docker_version['Server']['Version']
+    else
+      nil
+    end
   end
 end
 
@@ -45,24 +49,28 @@ def interfaces
         docker_json_str = Facter::Util::Resolution.exec(
           "#{docker_command} info --format '{{json .}}'",
         )
-        docker = JSON.parse(docker_json_str)
-        docker['network'] = {}
+        begin
+          docker = JSON.parse(docker_json_str)
+          docker['network'] = {}
 
-        docker['network']['managed_interfaces'] = {}
-        network_list = Facter::Util::Resolution.exec('docker network ls | tail -n +2')
-        docker_network_names = []
-        network_list.each_line { |line| docker_network_names.push line.split[1] }
-        docker_network_ids = []
-        network_list.each_line { |line| docker_network_ids.push line.split[0] }
-        docker_network_names.each do |network|
-          inspect = JSON.parse(Facter::Util::Resolution.exec("docker network inspect #{network}"))
-          docker['network'][network] = inspect[0]
-          network_id = docker['network'][network]['Id'][0..11]
-          interfaces.each do |iface|
-            docker['network']['managed_interfaces'][iface] = network if iface =~ %r{#{network_id}}
+          docker['network']['managed_interfaces'] = {}
+          network_list = Facter::Util::Resolution.exec('docker network ls | tail -n +2')
+          docker_network_names = []
+          network_list.each_line { |line| docker_network_names.push line.split[1] }
+          docker_network_ids = []
+          network_list.each_line { |line| docker_network_ids.push line.split[0] }
+          docker_network_names.each do |network|
+            inspect = JSON.parse(Facter::Util::Resolution.exec("docker network inspect #{network}"))
+            docker['network'][network] = inspect[0]
+            network_id = docker['network'][network]['Id'][0..11]
+            interfaces.each do |iface|
+              docker['network']['managed_interfaces'][iface] = network if iface =~ %r{#{network_id}}
+            end
           end
+          docker
+        rescue JSON::ParserError
+          nil
         end
-        docker
       end
     end
   end