retrospect-server-agent

Retrospect Server Agent is a node.js package for auto instrumenting a Node application and for providing custom baggage from the frontend events to the backend traces.

Follow the installation and setup for each service in your application.

Installation

This is a Node.js module available through the npm registry. Installation is done using the npm install command:

$ npm install retrospect-server-agent

Configuring Backend Tracing

1. Import this package into the main file that handles your service startup with the following:

    const customBaggage = require("retrospect-server-agent");

   
   

2. Load this package as middleware:

   app.use(customBaggage);

   • Important Note: You may load this middleware after loading app.use(cors()) but it must be loaded before your application routes.

   • Example:

     const cors = require("cors");
     const express = require("express");
     const app = express();
     
     const customBaggage = require("retrospect-server-agent");
     
     app.use(cors());
     
     app.use(customBaggage);
     
     const port = 3000;
     
     app.get("/", function (req, res, next) {
       //
     });
     
     //....

     
     

3. Edit the config.json file inside retrospect-server-agent package folder in node_modules.

   Configuration Options

   • serviceName: adds the name of your service that this package is tracing.

   • dbOptions: configuration settings for auto instrumenting available databases.

     • mongodb: set to true if your service uses mongodb which will enable instrumentation on mongodb queries. Otherwise set it to false.

     • redis: set to true if your service uses redis which will enable instrumentation on redis queries. Otherwise set it to false.

   • endpoint: configures the backend tracing data to be sent to a backend which is provided by Retrospect.

     • This api collects and transforms traces before storing them in Cassandra (also provided by Retrospect through a docker compose file). By default this api is listening on port 80.
     
     

   Configuration Steps

   • Edit the serviceName property to contain the name of your service.

   • For each property in the dbOptions object, change the value to true if your service queries the listed database.

   • Edit the endpoint property to contain the location of the Retrospect api.

     
     

   Example of config.js using a domain as an endpoint

   {
     "serviceName": "payment-service",
     "dbOptions": {
       "mongodb": true,
       "redis": false
     },
     "endpoint": "http://myapi.com"
   }

   
   

   Example of config.js using an endpoint in docker locally

   {
     "serviceName": "payment-service",
     "dbOptions": {
       "mongodb": true,
       "redis": false
     },
     "endpoint": "http://localhost"
   }

   
   

4. Update the start script in your service package.json file by appending the name of your service startup file.

      "start": "node -r retrospect-server-agent/tracing.js nameOfYourStartupFile.js"

   
   

5. Start your application by calling the start script.