kobp/lib/esm/src/utils/tracer.js

Koa Boilerplate with MikroORM

import { randomBytes } from 'crypto';
/**
 * Tracer Usage
 *
 * Extends this class. And initialize this with beforeFork middlewares
 *
 * Example:
 * ```ts
 *
 * class CustomTracer extends Tracer {
 *    ** my own functions **
 * }
 *
 * makeServer(
 *    ...,
 *    {
 *        middlewareBeforeFork: (app) => {
 *            app.use((ctx, next) => {
 *                ctx.tracer = new CustomTracer(ctx)
 *                await next()
 *            })
 *        },
 *        middlewareAfterFork: (app) => {
 *          app.use(Tracer.attach('tracer'))
 *        }
 *    }
 * )
 * ```
 */
export class Tracer {
    /**
     *
     * will be called automatically when the context is created
     */
    constructor(ctx) {
        const config = Tracer._config;
        const fromHeader = ctx.request.headers[config.requestTraceHeaderKey];
        const sanitized = (typeof fromHeader === 'string' ? fromHeader : (fromHeader && fromHeader.length > 0 && fromHeader[0] || ''));
        this.traceId = config.traceIdMaker(sanitized);
        this.context = ctx;
        this.context.traceId = this.traceId;
    }
    /**
     * Update tracer's configuration. You should call this only once.
     *
     * @param config
     */
    static config(config) {
        this._config = {
            ...this._config,
            ...config
        };
    }
}
/**
 * Access this parameter to customize the Tracer behavior
 */
Tracer._config = {
    requestTraceHeaderKey: 'x-trace-id',
    traceIdMaker: (currentKey) => {
        // Stack key when current ray run through multiple services.
        if (!currentKey) {
            return `${new Date().getTime().toString(32)}.${randomBytes(4).toString('hex').substring(0, 4)}`;
        }
        return `${currentKey}>${randomBytes(4).toString('hex').substring(0, 4)}`;
    }
};
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