logging to ILogger on config error

Author: brettsam

src/WebJobs.Script/Host/ScriptHost.cs

@@ -334,17 +334,27 @@ protected virtual void Initialize()
                     // If there's a parsing error, set up the logger and write out the previous messages so that they're
                     // discoverable in Application Insights. There's no filter, but that's okay since we cannot parse host.json to
                     // determine how to build the filtler.
-                    ConfigureLoggerFactory(ScriptConfig, FunctionTraceWriterFactory, _settingsManager, () => FileLoggingEnabled);
+                    ConfigureDefaultLoggerFactory();
                     ILogger startupErrorLogger = hostConfig.LoggerFactory.CreateLogger(LogCategories.Startup);
                     startupErrorLogger.LogInformation(readingFileMessage);
                     startupErrorLogger.LogInformation(readFileMessage);
 
                     throw new FormatException(string.Format("Unable to parse {0} file.", ScriptConstants.HostMetadataFileName), ex);
                 }
 
-                ApplyConfiguration(hostConfigObject, ScriptConfig);
+                try
+                {
+                    ApplyConfiguration(hostConfigObject, ScriptConfig);
+                }
+                catch (Exception)
+                {
+                    // If we have an error applying the configuration (for example, a value is invalid),
+                    // make sure we have a default LoggerFactory so that the error log can be written.
+                    ConfigureDefaultLoggerFactory();
+                    throw;
+                }
 
-                ConfigureLoggerFactory(ScriptConfig, FunctionTraceWriterFactory, _settingsManager, () => FileLoggingEnabled);
+                ConfigureDefaultLoggerFactory();
 
                 // Use the startupLogger in this class as it is concerned with startup. The public Logger is used
                 // for all other logging after startup.
@@ -544,6 +554,11 @@ private void LoadExtension(IExtensionConfigProvider instance, string locationHin
             config.AddExtension(instance);
         }
 
+        private void ConfigureDefaultLoggerFactory()
+        {
+            ConfigureLoggerFactory(ScriptConfig, FunctionTraceWriterFactory, _settingsManager, () => FileLoggingEnabled);
+        }
+
         internal static void ConfigureLoggerFactory(ScriptHostConfiguration scriptConfig, IFunctionTraceWriterFactory traceWriteFactory,
             ScriptSettingsManager settingsManager, Func<bool> isFileLoggingEnabled)
         {

test/WebJobs.Script.Tests.Integration/TestScripts/OutOfRange/host.json

@@ -0,0 +1,7 @@
+{    
+    "logger": {
+        "aggregator": {            
+            "flushTimeout": "00:30:00"
+        }
+    }
+}

test/WebJobs.Script.Tests.Integration/WebJobs.Script.Tests.Integration.csproj

@@ -973,6 +973,9 @@
     <None Include="TestScripts\Node\WebHookTrigger\function.json">
       <CopyToOutputDirectory>Always</CopyToOutputDirectory>
     </None>
+    <None Include="TestScripts\OutOfRange\host.json">
+      <CopyToOutputDirectory>Always</CopyToOutputDirectory>
+    </None>
     <None Include="TestScripts\Php\BlobTriggerToBlob\function.json">
       <CopyToOutputDirectory>Always</CopyToOutputDirectory>
     </None>

test/WebJobs.Script.Tests/ScriptHostTests.cs

@@ -382,6 +382,42 @@ public void Create_InvalidHostJson_ThrowsInformativeException()
             Assert.Equal("Invalid property identifier character: ~. Path '', line 2, position 4.", ex.InnerException.Message);
         }
 
+        [Fact]
+        public void Create_HostJsonValueError_LogsError()
+        {
+            // Try to load valid host.json file that has an out-of-range value.
+            // Ensure that it's logged to TraceWriter and ILogger
+
+            var traceWriter = new TestTraceWriter(TraceLevel.Verbose);
+            string rootPath = Path.Combine(Environment.CurrentDirectory, @"TestScripts\OutOfRange");
+
+            ScriptHostConfiguration scriptConfig = new ScriptHostConfiguration()
+            {
+                RootScriptPath = rootPath,
+                TraceWriter = traceWriter
+            };
+
+            TestLoggerProvider provider = new TestLoggerProvider();
+            scriptConfig.HostConfig.AddService<ILoggerFactoryBuilder>(new TestLoggerFactoryBuilder(provider));
+
+            var environment = new Mock<IScriptHostEnvironment>();
+            var eventManager = new Mock<IScriptEventManager>();
+
+            var ex = Assert.Throws<ArgumentOutOfRangeException>(() =>
+            {
+                ScriptHost.Create(environment.Object, eventManager.Object, scriptConfig, _settingsManager);
+            });
+
+            string msg = "ScriptHost initialization failed";
+            var trace = traceWriter.Traces.Single(t => t.Level == TraceLevel.Error);
+            Assert.Equal(msg, trace.Message);
+            Assert.Same(ex, trace.Exception);
+
+            var loggerMessage = provider.CreatedLoggers.Single().LogMessages.Single();
+            Assert.Equal(msg, loggerMessage.FormattedMessage);
+            Assert.Same(ex, loggerMessage.Exception);
+        }
+
         [Theory]
         [InlineData("host")]
         [InlineData("-function")]
@@ -1476,5 +1512,20 @@ public void Dispose()
             {
             }
         }
+
+        private class TestLoggerFactoryBuilder : ILoggerFactoryBuilder
+        {
+            private TestLoggerProvider _provider;
+
+            public TestLoggerFactoryBuilder(TestLoggerProvider provider)
+            {
+                _provider = provider;
+            }
+
+            public void AddLoggerProviders(ILoggerFactory factory, ScriptHostConfiguration scriptConfig, ScriptSettingsManager settingsManager)
+            {
+                factory.AddProvider(_provider);
+            }
+        }
     }
 }