Retrospect-server-agent NPM

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

Import this package into the main file that handles your service startup with the following:
```
const customBaggage = require("retrospect-server-agent");
```

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) {
  //
});

//....

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 a 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"
}
```
Update the start script in your service package.json file by appending the following in front of your startup file.
```
  "start": "node -r retrospect-server-agent/tracing.js nameOfYourStartupFile.js"
```
Start your application by calling the start script.