SimpleLambdaLogger

This is a prerelease version of SimpleLambdaLogger.

SimpleLambdaLogger is a scope-based and buffered logging library for AWS Lambda C# functions that output a single JSON log message to the CloudWatch console after every lambda invocation. Logging frequency is configurable, it can write once after every certain number of invocations. It is very easy to use and set up. It can be used even without configuration.

Getting started

First, add NuGet library into your project:

dotnet add package SimpleLambdaLogger --version 1.0.0-preview002

or

Install-Package SimpleLambdaLogger -Version 1.0.0-preview002

• This is the simplest way to use SimpleLambdaLogger without any configuration. The scope has it's own log level and overrides the default log level which is Information. The output contains duration field which shows execution time of each scope in miliseconds. contextId field can be used to track each scope by using AwsRequestId or any other correlation id value.

using SimpleLambdaLogger;

public class Function
{
    // input: "Hello World"
    public string FunctionHandler(string input, ILambdaContext context)
    {
        using (var scope = Scope.Begin<Function>(context.AwsRequestId, LogEventLevel.Trace))
        {
            scope.LogTrace(input);
            var result = input?.ToLower();
            scope.LogTrace(result);

            return result;
        }
    }
}

{
    "scope": "Function",
    "duration": 2,
    "contextId": "5a02102e-d4b1-4934-b8e6-59ce91e0e8dc",
    "success": true,
    "logs": [
        {
            "level": "Trace",
            "message": "Hello World",
            "timestamp": "2022-01-17T20:15:19.1193613+00:00"
        },
        {
            "level": "Trace",
            "message": "hello world",
            "timestamp": "2022-01-17T20:15:19.8179792+00:00"
        }
    ],
    "scopes": []
}

• success field depends on the min failure log level. By default, it is Error

using SimpleLambdaLogger;

public class Function
{
    // for the input: "Hello World"
    public async Task<string> FunctionHandler(string input, ILambdaContext context)
    {
        using (var scope = Scope.Begin<Function>(context.AwsRequestId, LogEventLevel.Trace))
        {
            scope.LogTrace(input);
            var result = input?.ToLower();
            scope.LogError(result);

            return result;
        }
    }
}

{
    "scope": "Function",
    "duration": 640,
    "contextId": "053a4e58-c8ea-4dbb-af93-1a81c0f65dac",
    "success": false,
    "logs": [
        {
            "level": "Trace",
            "message": "Hello World",
            "timestamp": "2022-01-17T21:49:13.7835968+00:00"
        },
        {
            "level": "Error",
            "message": "hello world",
            "timestamp": "2022-01-17T21:49:14.4236724+00:00"
        }
    ],
    "scopes": []
}

• Nested scopes

using SimpleLambdaLogger;

public class Function
{    
    // input: "Hello World"
    public string FunctionHandler(string input, ILambdaContext context)
    {
        using (var scope = Scope.Begin<Function>(context.AwsRequestId, LogEventLevel.Trace))
        {
            scope.LogTrace(input);
            var result = ToLowerCase(input);
            scope.LogTrace(result);

            return result;
        }
    }

    public string ToLowerCase(string input)
    {
        using (var scope = Scope.Begin("ToLowerCase", LogEventLevel.Trace))
        {
            scope.LogTrace(input);
            var result = input?.ToLower();
            scope.LogTrace(result);

            return result;
        }
    }
}

{
    "scope": "Function",
    "duration": 639,
    "contextId": "82cca306-15c6-450d-9059-65d64b1c134d",
    "success": true,
    "logs": [
        {
            "level": "Trace",
            "message": "Hello World",
            "timestamp": "2022-01-17T22:37:22.9324228+00:00"
        },
        {
            "level": "Trace",
            "message": "hello world",
            "timestamp": "2022-01-17T22:37:23.5714309+00:00"
        }
    ],
    "scopes": [
        {
            "scope": "Function.ToLowerCase",
            "duration": 479,
            "contextId": "82cca306-15c6-450d-9059-65d64b1c134d",
            "success": true,
            "logs": [
                {
                    "level": "Trace",
                    "message": "Hello World",
                    "timestamp": "2022-01-17T22:37:23.0919952+00:00"
                },
                {
                    "level": "Trace",
                    "message": "hello world",
                    "timestamp": "2022-01-17T22:37:23.5710483+00:00"
                }
            ],
            "scopes": []
        }
    ]
}

• Nested scopes with different log levels:

using SimpleLambdaLogger;

public class Function
{
    // input: "Hello World"
    public string FunctionHandler(string input, ILambdaContext context)
    {
        using (var scope = Scope.Begin<Function>(context.AwsRequestId, LogEventLevel.Critical))
        {
            scope.LogTrace(input);
            var result = ToLowerCase(input);
            scope.LogTrace(result);

            return result;
        }
    }

    public string ToLowerCase(string input)
    {
        using (var scope = Scope.Begin("ToLowerCase", LogEventLevel.Information))
        {
            scope.LogInformation(input);
            var result = input?.ToLower();
            scope.LogInformation(result);

            return result;
        }
    }
}

The inner scope satisfies with the minimum log level:

{
    "scope": "Function",
    "duration": 0,
    "contextId": "94ae51c0-a41d-4010-b6a4-576cb05cafaf",
    "success": true,
    "logs": [
        {
            "level": "Trace",
            "message": "Hello World",
            "timestamp": "2022-01-17T22:53:59.4181365+00:00"
        },
        {
            "level": "Trace",
            "message": "hello world",
            "timestamp": "2022-01-17T22:53:59.4182013+00:00"
        }
    ],
    "scopes": [
        {
            "scope": "Function.ToLowerCase",
            "duration": 0,
            "contextId": "94ae51c0-a41d-4010-b6a4-576cb05cafaf",
            "success": true,
            "logs": [
                {
                    "level": "Information",
                    "message": "Hello World",
                    "timestamp": "2022-01-17T22:53:59.4181869+00:00"
                },
                {
                    "level": "Information",
                    "message": "hello world",
                    "timestamp": "2022-01-17T22:53:59.4181972+00:00"
                }
            ],
            "scopes": []
        }
    ]
}

• Logging rate with initial configuration:

public class Function
{
    public Function()
    {
        Scope.Configure(logLevel: LogEventLevel.Trace, loggingRate: 10);
    }
    
    // input: "Hello World"
    public string FunctionHandler(string input, ILambdaContext context)
    {
        using (var scope = Scope.Begin<Function>(context.AwsRequestId))
        {
            scope.LogInformation(input);
            var result = input.ToLower();
            scope.LogInformation(result);
            return result;
        }
    }
}

It outputs once for every 10 invocations:

{
    "scope": "Function",
    "duration": 0,
    "contextId": "b1557c4d-42d7-41e3-afaa-471870f6971a",
    "success": true,
    "logs": [
        {
            "level": "Information",
            "message": "Hello World",
            "timestamp": "2022-01-17T22:57:29.6560841+00:00"
        },
        {
            "level": "Information",
            "message": "hello world",
            "timestamp": "2022-01-17T22:57:29.656128+00:00"
        }
    ],
    "scopes": []
}

• Multiple asyc scopes:

public class Function
{
    // input: "Hello World"
    public async Task<string> FunctionHandler(string input, ILambdaContext context)
    {
        using (var scope = Scope.Begin<Function>(context.AwsRequestId, LogEventLevel.Trace))
        {
            scope.LogTrace(input);
            await Task.WhenAll(ToLower(input), ToUpper(input));
            return input;
        }
    }

    public async Task ToLower(string input)
    {
        using (var scope = Scope.Begin("ToLower"))
        {
            scope.LogTrace(input.ToLower());
        }
    }
    
    public async Task ToUpper(string input)
    {
        using (var scope = Scope.Begin("ToUpper"))
        {
            scope.LogTrace(input.ToUpper());
        }
    }
}

{
    "scope": "Function",
    "duration": 680,
    "contextId": "c2b457a8-7e69-45bc-b585-f4a52c95e261",
    "success": true,
    "logs": [
        {
            "level": "Trace",
            "message": "Hello World",
            "timestamp": "2022-01-17T23:26:24.4333478+00:00"
        }
    ],
    "scopes": [
        {
            "scope": "Function.ToLower",
            "duration": 498,
            "contextId": "c2b457a8-7e69-45bc-b585-f4a52c95e261",
            "success": true,
            "logs": [
                {
                    "level": "Trace",
                    "message": "hello world",
                    "timestamp": "2022-01-17T23:26:25.1119557+00:00"
                }
            ],
            "scopes": []
        },
        {
            "scope": "Function.ToUpper",
            "duration": 0,
            "contextId": "c2b457a8-7e69-45bc-b585-f4a52c95e261",
            "success": true,
            "logs": [
                {
                    "level": "Trace",
                    "message": "HELLO WORLD",
                    "timestamp": "2022-01-17T23:26:25.1130251+00:00"
                }
            ],
            "scopes": []
        }
    ]
}

Credits