Skip to content


Subversion checkout URL

You can clone with
Download ZIP
log4net appender to MongoDB database.
C# PowerShell Shell
Branch: master

MongoDB appender for log4net

The title says it all. Check Log4Net site or MongoDB site if you need more info.

This is the official .NET implementation for the log4mongo project

To get started, check out @sammleach blog post: .NET Logging with log4mongo-net


Get it on NuGet, or download sources and run build.cmd to build

Appender configuration sample

<appender name="MongoDBAppender" type="Log4Mongo.MongoDBAppender, Log4Mongo">
    MongoDB database connection in the format:
    See for connectionstring options 
    If no database specified, default to "log4net"
    <connectionString value="mongodb://localhost" />
    Name of connectionString defined in web/app.config connectionStrings group, the format is the same as connectionString value.
    Optional, If not provided will use connectionString value
    <connectionStringName value="mongo-log4net" />
    Name of the collection in database
    Optional, Defaults to "logs"
    <collectionName value="logs" />

        <name value="timestamp" />
        <layout type="log4net.Layout.RawTimeStampLayout" />
        <name value="level" />
        <layout type="log4net.Layout.PatternLayout" value="%level" />
        <name value="thread" />
        <layout type="log4net.Layout.PatternLayout" value="%thread" />
        <name value="logger" />
        <layout type="log4net.Layout.PatternLayout" value="%logger" />
        <name value="message" />
        <layout type="log4net.Layout.PatternLayout" value="%message" />
        <name value="mycustomproperty" />
        <layout type="log4net.Layout.RawPropertyLayout">
            <key value="mycustomproperty" />

Note about Default Write Concern Change in driver 1.7+

10gen changed the default value for WriteConcern. This change is implemented in MongoDB C# driver starting from 1.7 and is effective only when used with the new MongoDB.Driver.MongoClient class.

For logging concern, the old default is usually better so for now Log4Mongo will keep creating database connection in the old way (by using MongoDB.Driver.MongoServer.Create). At some point (maybe with a major release) we will switch and start using MongoDB.Driver.MongoClient class, so it's best if you explicitly specify WriteConcern related options in the connection string, as described here: Write Concern Options




Thanks to JetBrains for providing us licenses for it's excellent tool ReSharper


Something went wrong with that request. Please try again.