A simple, compact JSON-based event format for Serilog. CompactJsonFormatter significantly reduces the byte count of small log events when compared with Serilog's default JsonFormatter, while remaining human-readable. It achieves this through shorter built-in property names, a leaner format, and by excluding redundant information.

A simple Hello, {User} event.

{"@t":"2016-06-07T03:44:57.8532799Z","@mt":"Hello, {User}","User":"nblumhardt"}

Install from NuGet:

Install-Package Serilog.Formatting.Compact

The formatter is used in conjunction with sinks that accept ITextFormatter. For example, the file sink:

Log.Logger = new LoggerConfiguration()
  .WriteTo.File(new CompactJsonFormatter(), "./logs/myapp.json")
  .CreateLogger();

To specify the formatter in XML <appSettings> provide its assembly-qualified type name:

<appSettings>
  <add key="serilog:using:File" value="Serilog.Sinks.RollingFile" />
  <add key="serilog:write-to:File.path" value="./logs/myapp.json" />
  <add key="serilog:write-to:File.formatter"
       value="Serilog.Formatting.Compact.CompactJsonFormatter, Serilog.Formatting.Compact" />

CompactJsonFormatter will preserve the message template, properties, and formatting information so that the rendered message can be created at a later point. When the JSON is intended for consumption in an environment without message template rendering, RenderedCompactJsonFormatter can be used instead.

Instead of the message template, RenderedCompactJsonFormatter writes the fully-rendered message, as well as an event id generated from the message template, into the event:

{"@t":"2016-06-07T03:44:57.8532799Z","@m":"Hello, \"nblumhardt\"","@i":"7a8b9c0d","User":"nblumhardt"}

The format written by the compact formatters is specified generically so that implementations for other logging libraries, including Microsoft.Extensions.Logging, are possible if desired.

Each event is a JSON object with event data at the top level. Any JSON property on the payload object is assumed to be a regular property of the event, apart from the reified properties below.

The format defines a handful of reified properties that have special meaning:

The @ sigil may be escaped at the start of a user property name by doubling, e.g. @@name denotes a property called @name.

When events are batched into a single payload, a newline-delimited stream of JSON documents is required. Either \n or \r\n delimiters may be used. Batches of newline-separated compact JSON events can use the (unofficial) MIME type application/vnd.serilog.clef.

Versioning would be additive only, with no version identifier; implementations should treat any unrecognised reified properties as if they are user data.

The output and benchmarks below compare the compact JSON formatter with Serilog's built-in JsonFormatter.

Event

Log.Information("Hello, {@User}, {N:x8} at {Now}",
  new
  {
    Name = "nblumhardt",
    Tags = new[] { 1, 2, 3 }
  },
  123,
  DateTime.Now);

Default JsonFormatter 292 bytes

{"Timestamp":"2016-06-07T13:44:57.8532799+10:00","Level":"Information","MessageT
emplate":"Hello, {@User}, {N:x8} at {Now}","Properties":{"User":{"Name":"nblumha
rdt","Tags":[1,2,3]},"N":123,"Now":"2016-06-07T13:44:57.8532799+10:00"},"Renderi
ngs":{"N":[{"Format":"x8","Rendering":"0000007b"}]}}

CompactJsonFormatter 187 bytes (0.64)

{"@t":"2016-06-07T03:44:57.8532799Z","@mt":"Hello, {@User}, {N:x8} at {Now}","@r
":["0000007b"],"User":{"Name":"nblumhardt","Tags":[1,2,3]},"N":123,"Now":2016-06
-07T13:44:57.8532799+10:00}

Formatting benchmark

See test/Serilog.Formatting.Compact.Tests/FormattingBenchmarks.cs.

Opening serilog-formatting-compact.sln requires VS2015 Update 3 with the .NET Core tooling to be installed.
See: https://www.microsoft.com/net/core#windows