triage-client-go

Thin Go client for subscribing to the Triage service for Kafka.

How it works

The triage-client-go library interacts with a Triage deployment by running a gRPC server that listens for a incoming messages (gRPC method calls). Users pass a message handler function to the library, which acts as middleware. Each message received is passed to the message handler, and triage-client-go uses the return of the message handler to determine the response sent back to Triage.

How to get it

To get the latest version, use go 1.19* and fetch using the go get command. For example:

go get github.com/team-triage/triage-client-go

How to use it

This client provides 3 utility functions used for interacting with Triage.

OnMessage

The OnMessage(messageHandler func(string) int) function accepts a messageHandler function. This function should accept a string (the value of the Kafka message) and return either integers 1 or -1 , representing the successful or unsuccessful processing of a message.

The function passed to OnMessage acts as middleware - when the gRPC server receives a message from Triage, it will call the messageHandler passed to it to determine the response sent back to Triage.

A 1 sends a positive acknowledgment to Triage, letting it know that it is safe to commit this message's offset back to Kafka.

A -1 sends a negative acknowledgment to Triage. Triage will store this message in a DynamoDB table for later processing, before committing it's offset back to Kafka.

Listen

The Listen(grpcPort string) function starts a gRPC server on the specified port. This port should be the same that is sent to Triage by RequestConnection. This should be called before RequestConnection (see below).

RequestConnection

The RequestConnection(triageNetworkAddress string, grpcPort string, authToken string) function makes an initial request to Triage, informing it that the consumer application is ready to begin accepting connections. It accepts 3 arguments:

• triageNetworkAddress: The network address provided during Triage deployment. This is typically an AWS internet-facing application load balancer address.
• grpcPort: The port used by the consumer application to listen for incoming messages.
• authToken: The authentication key provided during Triage deployment.

Example Consumer Application

package main

import (
  client "github.com/team-triage/triage-client-go"
  "sync"
)

var wg sync.WaitGroup

func main() {
  grpcPort := "9000"
  triageNetworkAddress := "Triag-Triage-123456.us-west-1.elb.amazonaws.com"
  authKey := "ABADAUTHKEY"

  client.OnMessage(dummyMessageHandler)
  
  wg.Add(1)
  client.Listen(grpcPort)
  
  res := client.RequestConnection(triageNetworkAddress, grpcPort, authKey)
  
  if res.StatusCode == http.StatusOK {
		fmt.Printf("Status Code: %v \n ready to receive messages!\n", res.StatusCode)
	} else {
		fmt.Printf("Status Code: %v\n There was a problem connecting to Triage :(\n", res.StatusCode)
	}
  
  wg.Wait()
}

func dummyMessageHandler(msg string) int {
  if len(msg) > 4 {
    return 1
  }
  return -1
}