@google-cloud/logging-winston/build/src/default-metadata.js

"use strict";
// Copyright 2019 Google LLC
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//      http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
Object.defineProperty(exports, "__esModule", { value: true });
exports.getDefaultMetadataForTracing = void 0;
const common_1 = require("./common");
/**
 * 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.
 *
 * See https://github.com/googleapis/nodejs-logging-winston/issues/287 for
 * more information.
 */
function getDefaultMetadataForTracing() {
    const agent = global._google_trace_agent;
    // Enable log-trace correlation if the Trace Agent API is compatible.
    const enableThunkAgent = !!(agent &&
        agent.getCurrentContextId &&
        agent.getWriterProjectId);
    const defaultMeta = {};
    // Make defaultMeta.timestamp return the current timestamp any time it's
    // accessed.
    Object.defineProperty(defaultMeta, 'timestamp', {
        enumerable: true,
        get: () => new Date(),
    });
    if (enableThunkAgent) {
        // Make defaultMeta[LOGGING_TRACE_KEY] return the current trace ID any time
        // it's accessed.
        const loggingTraceKey = common_1.LOGGING_TRACE_KEY;
        Object.defineProperty(defaultMeta, loggingTraceKey, {
            enumerable: true,
            get: () => {
                const traceId = agent.getCurrentContextId();
                if (!traceId) {
                    return null;
                }
                const traceProjectId = agent.getWriterProjectId();
                if (!traceProjectId) {
                    return null;
                }
                return `projects/${traceProjectId}/traces/${traceId}`;
            },
        });
    }
    return defaultMeta;
}
exports.getDefaultMetadataForTracing = getDefaultMetadataForTracing;
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