Log value of FUNCTIONS_EXTENSION_VERSION on host start. Fixes #1835

Author: alrod

src/WebJobs.Script/EnvironmentSettingNames.cs

@@ -23,5 +23,6 @@ public static class EnvironmentSettingNames
         public const string AzureWebJobsSecretStorageType = "AzureWebJobsSecretStorageType";
         public const string AppInsightsInstrumentationKey = "APPINSIGHTS_INSTRUMENTATIONKEY";
         public const string ProxySiteExtensionEnabledKey = "ROUTING_EXTENSION_VERSION";
+        public const string FunctionsExtensionVersion = "FUNCTIONS_EXTENSION_VERSION";
     }
 }

src/WebJobs.Script/Host/ScriptHostManager.cs

@@ -143,8 +143,9 @@ public bool CanInvoke()
 
                     OnHostCreated();
 
-                    string message = string.Format("Starting Host (HostId={0}, Version={1}, ProcessId={2}, Debug={3}, Attempt={4})",
-                        newInstance.ScriptConfig.HostConfig.HostId, ScriptHost.Version, Process.GetCurrentProcess().Id, newInstance.InDebugMode.ToString(), consecutiveErrorCount);
+                    string message = string.Format("Starting Host (HostId={0}, Version={1}, ProcessId={2}, Debug={3}, Attempt={4}, FunctionsExtensionVersion={5})",
+                        newInstance.ScriptConfig.HostConfig.HostId, ScriptHost.Version, Process.GetCurrentProcess().Id, newInstance.InDebugMode.ToString(), consecutiveErrorCount,
+                        _settingsManager.GetSetting(EnvironmentSettingNames.FunctionsExtensionVersion));
                     _traceWriter?.Info(message);
                     _logger?.LogInformation(message);
 

test/WebJobs.Script.Tests.Integration/Host/WebScriptHostManagerTests.cs

@@ -319,7 +319,7 @@ public Fixture()
                     "Info Host lock lease acquired by instance ID '(.+)'",
                     "Info Function 'Excluded' is marked as excluded",
                     @"Info Generating ([0-9]+) job function\(s\)",
-                    @"Info Starting Host \(HostId=function-tests-node, Version=(.+), ProcessId=[0-9]+, Debug=False, Attempt=0\)",
+                    @"Info Starting Host \(HostId=function-tests-node, Version=(.+), ProcessId=[0-9]+, Debug=False, Attempt=0, FunctionsExtensionVersion=\)",
                     "Info WebJobs.Indexing Found the following functions:",
                     "Info The next 5 occurrences of the schedule will be:",
                     "Info WebJobs.Host Job host started",