Allow configuration from contents of Serilog section

src/Serilog.Settings.Configuration/ConfigurationLoggerConfigurationExtensions.cs

@@ -228,20 +228,20 @@ public static LoggerConfiguration Configuration(
     static ConfigurationReader GetConfigurationReader(IConfiguration configuration, ConfigurationReaderOptions readerOptions, DependencyContext dependencyContext)
     {
         var assemblyFinder = dependencyContext == null ? AssemblyFinder.Auto() : AssemblyFinder.ForDependencyContext(dependencyContext);
-        var section = configuration.GetSection(readerOptions.SectionName);
+        var section = string.IsNullOrWhiteSpace(readerOptions.SectionName) ? configuration : configuration.GetSection(readerOptions.SectionName);
         return new ConfigurationReader(section, assemblyFinder, readerOptions, configuration);
     }
 
     static ConfigurationReader GetConfigurationReader(IConfiguration configuration, ConfigurationReaderOptions readerOptions, ConfigurationAssemblySource source)
     {
         var assemblyFinder = AssemblyFinder.ForSource(source);
-        var section = configuration.GetSection(readerOptions.SectionName);
+        var section = string.IsNullOrWhiteSpace(readerOptions.SectionName) ? configuration : configuration.GetSection(readerOptions.SectionName);
         return new ConfigurationReader(section, assemblyFinder, readerOptions, configuration);
     }
 
     static ConfigurationReader GetConfigurationReader(IConfiguration configuration, ConfigurationReaderOptions readerOptions, IReadOnlyCollection<Assembly> assemblies)
     {
-        var section = configuration.GetSection(readerOptions.SectionName);
+        var section = string.IsNullOrWhiteSpace(readerOptions.SectionName) ? configuration : configuration.GetSection(readerOptions.SectionName);
         return new ConfigurationReader(section, assemblies, new ResolutionContext(configuration, readerOptions));
     }
 }

src/Serilog.Settings.Configuration/Settings/Configuration/ConfigurationReader.cs

@@ -17,12 +17,12 @@ class ConfigurationReader : IConfigurationReader
 {
     const string LevelSwitchNameRegex = @"^\${0,1}[A-Za-z]+[A-Za-z0-9]*$";
 
-    readonly IConfigurationSection _section;
+    readonly IConfiguration _section;
     readonly IReadOnlyCollection<Assembly> _configurationAssemblies;
     readonly ResolutionContext _resolutionContext;
     readonly IConfigurationRoot _configurationRoot;
 
-    public ConfigurationReader(IConfigurationSection configSection, AssemblyFinder assemblyFinder, ConfigurationReaderOptions readerOptions, IConfiguration configuration = null)
+    public ConfigurationReader(IConfiguration configSection, AssemblyFinder assemblyFinder, ConfigurationReaderOptions readerOptions, IConfiguration configuration = null)
     {
         _section = configSection ?? throw new ArgumentNullException(nameof(configSection));
         _configurationAssemblies = LoadConfigurationAssemblies(_section, assemblyFinder);
@@ -31,7 +31,7 @@ public ConfigurationReader(IConfigurationSection configSection, AssemblyFinder a
     }
 
     // Used internally for processing nested configuration sections -- see GetMethodCalls below.
-    internal ConfigurationReader(IConfigurationSection configSection, IReadOnlyCollection<Assembly> configurationAssemblies, ResolutionContext resolutionContext)
+    internal ConfigurationReader(IConfiguration configSection, IReadOnlyCollection<Assembly> configurationAssemblies, ResolutionContext resolutionContext)
     {
         _section = configSection ?? throw new ArgumentNullException(nameof(configSection));
         _configurationAssemblies = configurationAssemblies ?? throw new ArgumentNullException(nameof(configurationAssemblies));
@@ -298,7 +298,7 @@ void ApplyEnrichment(LoggerConfiguration loggerConfiguration)
         }
     }
 
-    internal ILookup<string, Dictionary<string, IConfigurationArgumentValue>> GetMethodCalls(IConfigurationSection directive)
+    internal ILookup<string, Dictionary<string, IConfigurationArgumentValue>> GetMethodCalls(IConfiguration directive)
     {
         var children = directive.GetChildren().ToList();
 
@@ -356,7 +356,7 @@ internal static IConfigurationArgumentValue GetArgumentValue(IConfigurationSecti
         return argumentValue;
     }
 
-    static IReadOnlyCollection<Assembly> LoadConfigurationAssemblies(IConfigurationSection section, AssemblyFinder assemblyFinder)
+    static IReadOnlyCollection<Assembly> LoadConfigurationAssemblies(IConfiguration section, AssemblyFinder assemblyFinder)
     {
         var serilogAssembly = typeof(ILogger).Assembly;
         var assemblies = new Dictionary<string, Assembly> { [serilogAssembly.FullName] = serilogAssembly };

test/Serilog.Settings.Configuration.Tests/ConfigurationSettingsTests.cs

@@ -56,6 +56,31 @@ public void PropertyEnrichmentIsApplied()
         Assert.Equal("Test", evt.Properties["App"].LiteralValue());
     }
 
+    [Theory]
+    [InlineData(null)]
+    [InlineData("")]
+    public void CanReadWithoutSerilogSection(string sectionName)
+    {
+        LogEvent evt = null;
+
+        var json = """
+            {
+                "Properties": {
+                    "App": "Test"
+                }
+            }
+            """;
+
+        var log = ConfigFromJson(json, options: new ConfigurationReaderOptions { SectionName = sectionName })
+            .WriteTo.Sink(new DelegatingSink(e => evt = e))
+            .CreateLogger();
+
+        log.Information("Has a test property");
+
+        Assert.NotNull(evt);
+        Assert.Equal("Test", evt.Properties["App"].LiteralValue());
+    }
+
     [Theory]
     [InlineData("extended syntax", """
     {