apm.ts

import { IncomingMessage, ServerResponse } from 'http'
import tracer, { Span } from 'dd-trace'
import * as url from 'url'

const HTTP_IP = 'http.ip'
const HTTP_METHOD = 'http.method'
const HTTP_PATH = 'http.uri.path'
const HTTP_QUERY = 'http.uri.query'
const HTTP_RESPONSE_STATUS = 'http.response.status'
const USER_AGENT = 'http.useragent'

const requestHook = (
    span: Span | undefined,
    req: IncomingMessage | undefined,
    res: ServerResponse | undefined,
): void => {
    if (span && req) {
        if (req.url) {
            const parsed = url.parse(req.url.toString(), true)
            span.setTag(HTTP_PATH, parsed.path)
            span.setTag(HTTP_QUERY, parsed.query)
        }
        span.setTag(HTTP_IP, req.connection.remoteAddress)
        span.setTag(USER_AGENT, req.headers['user-agent'])
        span.setTag(HTTP_METHOD, req.method)
    }

    if (span && res) {
        span.setTag(HTTP_RESPONSE_STATUS, res.statusCode)
    }
}

tracer.use('express', {
    hooks: { request: requestHook },
})

export { requestHook }
export default tracer