Logging Package

The Logging package is a Go library that provides a simple and flexible logging system built on top of the Zerolog library. It allows you to log messages with different severity levels, add custom key-value pairs to log messages, and integrate with OpenTelemetry tracing to include trace and span information in log messages.

Features

Six log levels: debug, info, warn, error, fatal, and panic
Structured logging with custom key-value pairs
Integration with OpenTelemetry tracing to include trace and span information
Customizable output writer
Initialization with common attribs for consistent logging across the application

Installation

To install the Logging package, use the following command:

go get github.com/twistingmercury/telemetry

Usage

Initialization

Before using the Logging package, you need to initialize it with the desired log level, common attribs, and output writer:

import "github.com/twistingmercury/telemetry/logging"

err := logging.InitializeWithPort(zerolog.DebugLevel, attribs, os.Stdout)
if err != nil {
    // Handle initialization error
}

zerolog.DebugLevel specifies the minimum log level to be logged. You can use zerolog.InfoLevel, zerolog.WarnLevel, zerolog.ErrorLevel, zerolog.FatalLevel, or zerolog.PanicLevel based on your needs.
attribs is an instance of common.Attributes that contains common attribs to be included in every log message.
os.Stdout is the output writer where the log messages will be written. You can use any io.Writer implementation, such as a file or a network connection.

Logging Messages

The Logging package provides functions to log messages with different severity levels:

logging.Debug("Debug message", logging.KeyValue{Key: "key", Value: "value"})
logging.Info("Info message", logging.KeyValue{Key: "key", Value: 123})
logging.Warn("Warn message")
logging.Error(err, "Error message")
logging.Fatal(err, "Fatal message")
logging.Panic(err, "Panic message")

Each function takes a message string and optional logging.KeyValue pairs to add custom key-value pairs to the log message.

Logging with Context

If you have a span context from OpenTelemetry tracing, you can include it in the log messages using the WithContext variants of the logging functions:

// _, span := tracing.StartSpan(...)
// spanCtx := span.SpanContext()

logging.DebugWithContext(&spanCtx, "debug message")
logging.InfoWithContext(&spanCtx, "info message")
logging.WarnWithContext(&spanCtx, "warn message")
logging.ErrorWithContext(&spanCtx, err, "error message")
logging.FatalWithContext(&spanCtx, err, "fatal message")
logging.PanicWithContext(&spanCtx, err, "panic message")

The spanCtx parameter is a pointer to trace.SpanContext that contains the trace and span information to be included in the log message.

Custom Key-Value Pairs

You can add custom key-value pairs to log messages using the logging.KeyValue struct:

logging.Info(
    "Info message", 
    logging.KeyValue{Key: "key1", Value: "value1"}, 
    logging.KeyValue{Key: "key2", Value: 123},
)

logging.InfoWithContext(
    &spanCtx, 
    "Info message", 
    logging.KeyValue{Key: "key1", Value: "value1"}, 
    logging.KeyValue{Key: "key2", Value: 123},
)

The Key field is a string representing the key, and the Value field can be of any type that Zerolog supports.

Contributing

Contributions to the Logging package are welcome! If you find any issues or have suggestions for improvements, please open an issue or submit a pull request on the GitHub repository.

License

The Logging package is open-source and released under the MIT License.

# README