otel-json-logger

JSON diagnose logger for OpenTelemetry

Installation

npm install --save @dreamit/otel-json-logger

TypeScript declarations are provided within the project.

Compatibility

otel-json-logger is compatible with @opentelemetry/api version ^1.6.0.

Features

• Provides JSON Logger for OpenTelemetry DiagLogger interface
• Stringifies/inspects messages with objects and arrays as well as log arguments to avoid breaking logging tools
• Creates ISODate timestamp for log entry

Usage

Create a JsonDiagLogger object by providing a fitting loggerName and serviceName. The logger can be used standalone to log JSON to console as well as a global DiagLogger.

import { JsonDiagLogger } from '@dreamit/otel-json-logger'
import { diag, DiagLogLevel } from "@opentelemetry/api";

// Standalone
const logger = new JsonDiagLogger({
    loggerName: 'test-logger', // The loggerName printed in field "logger"
    serviceName: 'test-service', // The serviceName printed in field "serviceName"
    minLogLevel: LogLevel.info, // Optional: The minimum log level to use. Default: Does not check for min LogLevel.
    logFirstIncomingRequest: true, // Optional: The first incoming request will be logged. Other messages on debug level will be ignored. Default: false. Note: If you use diag.setLogger ensure that at least "LogLevel.debug" is set, otherwise the message will be ignored.
    logLevelForServiceRequestErrorMessages: LogLevel.info, // Optional: The log level to use for error message "Service request". These contain request information that might not be logged on error level.
    logLevelForTimeoutErrorMessages: LogLevel.info, // Optional: The log level to use for Timeout related messages. These might be of short nature and be downgraded or ignored.
    logLevelForVerbose: LogLevel.off // Optional: Set LogLevel for verbose entries or ignore them
    truncateLimit: 200 // Optional:  The length of the message before the message gets truncated. Default: undefined/0 (off).
    truncatedText: '_TRC_' // Optional: The text to display if a message is truncated.
})
logger.debug('test', 1, {name: 'myname'})

// Add as global DiagLogger
diag.setLogger(logger, DiagLogLevel.ERROR)

JsonDiagLogger functions

General functions

• createLogEntry: Creates and returns a log entry of type LogEntry with the provided information.
• logMessage: Central function being called by all DiagLogger interface functions. Calls createLogEntry, stringifies the result and calls console.log().
• formatMessage: Formats the message. If the message contains an object or array wrap it in JSON.stringify to avoid these being interpreted as JSON objects.
• setOptions: Sets the LoggerOptions to be used for logging. Can be called after constructor call to set new/other options.
• containsTimeout: Check if the message contains a Timeout information like "4 DEADLINE_EXCEEDED" or "14 UNAVAILABLE"
• isIncomingRequestLogMessage: Checks if the arguments are part of an incomingRequest message, i.e. the first argument contains the text 'incomingRequest'
• isEqualOrHigherMinLogLevel: Checks if the log level is equal or higher than the minimum log level

DiagLogger interface functions

• debug: Logs a debug message
• error: Logs an error message
• info: Logs an info message
• verbose: Logs a warn message
• warn: Logs a verbose message

LogLevel enum values

• DEBUG
• ERROR
• INFO
• OFF : Do not log these entries!
• VERBOSE
• WARN

Contact

If you have questions or issues please visit our Issue page and open a new issue if there are no fitting issues for your topic yet.

License

otel-json-logger is under MIT-License.