Returns an object that can be passed to Winston.createLogger as defaultMeta to allow log-trace correlation with Winston 3. Log-trace correlation with Winston 3 is broken because the trace ID to be correlated with a log isn't evaluated when the log function is called, but rather when the log is written, which happens at some future point where the trace ID may no longer be accurate. To circumvent this, we take advantage of the fact that defaultMeta is copied when a log function is called, and use a dynamic property getter to evaluate the trace ID upon that copy.
We apply the same principle for timestamps, which is not strictly necessary for tracing but allows for more accurate timestamps in general.
If there are other default metadata fields with which the return value of this function must be merged, this object MUST be the base object. In other words, do not use the return value of this function as the non-first argument to Object.assign, or it will not work.
[[["Easy to understand","easyToUnderstand","thumb-up"],["Solved my problem","solvedMyProblem","thumb-up"],["Other","otherUp","thumb-up"]],[["Hard to understand","hardToUnderstand","thumb-down"],["Incorrect information or sample code","incorrectInformationOrSampleCode","thumb-down"],["Missing the information/samples I need","missingTheInformationSamplesINeed","thumb-down"],["Other","otherDown","thumb-down"]],["Last updated 2025-09-04 UTC."],[],[],null,["# Package @google-cloud/logging-winston (6.0.0)\n\nVersion latestkeyboard_arrow_down\n\n- [6.0.0 (latest)](/nodejs/docs/reference/logging-winston/latest/overview)\n- [5.2.2](/nodejs/docs/reference/logging-winston/5.2.2/overview)\n- [5.1.8](/nodejs/docs/reference/logging-winston/5.1.8/overview)\n- [4.2.2](/nodejs/docs/reference/logging-winston/4.2.2/overview)\n- [4.1.3](/nodejs/docs/reference/logging-winston/4.1.3/overview)\n- [4.0.5](/nodejs/docs/reference/logging-winston/4.0.5/overview) \n\nClasses\n-------\n\n### [LoggingWinston](/nodejs/docs/reference/logging-winston/latest/logging-winston/loggingwinston)\n\nThis module provides support for streaming your winston logs to \\[Cloud Logging\\](\u003chttps://cloud.google.com/logging\u003e).\n\nInterfaces\n----------\n\n### [Options](/nodejs/docs/reference/logging-winston/latest/logging-winston/options)\n\nVariables\n---------\n\n### express.REQUEST_LOG_SUFFIX\n\n REQUEST_LOG_SUFFIX = \"_reqlog\"\n\n### LOGGING_SAMPLED_KEY\n\n LOGGING_SAMPLED_KEY = \"logging.googleapis.com/trace_sampled\"\n\n### LOGGING_SPAN_KEY\n\n LOGGING_SPAN_KEY = \"logging.googleapis.com/spanId\"\n\n### LOGGING_TRACE_KEY\n\n LOGGING_TRACE_KEY = \"logging.googleapis.com/trace\"\n\nFunctions\n---------\n\n### express.makeMiddleware(logger, transport)\n\n export declare function makeMiddleware(logger: winston.Logger, transport: LoggingWinston): Promise\n\n### express.makeMiddleware(logger, options)\n\n export declare function makeMiddleware(logger: winston.Logger, options?: Options): Promise\n\n### getCurrentTraceFromAgent()\n\n export declare function getCurrentTraceFromAgent(): string | null;\n\n### getDefaultMetadataForTracing()\n\n export declare function getDefaultMetadataForTracing(): {};\n\nReturns an object that can be passed to Winston.createLogger as defaultMeta to allow log-trace correlation with Winston 3. Log-trace correlation with Winston 3 is broken because the trace ID to be correlated with a log isn't evaluated when the log function is called, but rather when the log is written, which happens at some future point where the trace ID may no longer be accurate. To circumvent this, we take advantage of the fact that defaultMeta is copied when a log function is called, and use a dynamic property getter to evaluate the trace ID upon that copy.\n\nWe apply the same principle for timestamps, which is not strictly necessary for tracing but allows for more accurate timestamps in general.\n\nIf there are other default metadata fields with which the return value of this function must be merged, this object MUST be the base object. In other words, do not use the return value of this function as the non-first argument to Object.assign, or it will not work.\n\nSee \u003chttps://github.com/googleapis/nodejs-logging-winston/issues/287\u003e for more information."]]
