Review Rewards Example App (Twilio Go SDK)

An example application made by the Developer Experience - Developer Interfaces team to showcase the usage of the Twilio Go SDK, Programmable Messaging, and Programmable Voice.

Made for the purpose of providing an example application to train individuals on how Golang and the Twilio Go SDK may be used to build a web application.

Prerequisites

Before installing and running this application, please ensure that you complete the following prerequisites:

Have a MacOS and Linux environment
Install Go
Install a Code Editor
- We recommend Visual Studio Code with the Go Extension installed
Obtain a Twilio account and phone number with Messaging and Voice enabled
Save your Twilio account SID and Auth Token in the following environment variables:
- TWILIO_ACCOUNT_SID
- TWILIO_AUTH_TOKEN
Have twilio-cli installed and logged into your account to easily update your twilio phone number configuration with a single CLI command
Obtain access to the Twilio Console
Install/obtain a localhost tunnel to access your localhost server on the internet. We'll use ngrok in our examples.

Build the application

To build the application, run go build -o out/bin/sample-twilio-go main.go. This compiles the "sample-twilio-go" application binary and stores it in the out/bin directory.

Run the application

To run the application, first start ngrok to forward HTTP traffic to port 8080 in a separate terminal:

ngrok http 8080

Copy the Forwarding URL from ngrok's output. The URL should look something like this:

https://1404-2601-282-1200-118-e1d0-ba12-d474-d43a.ngrok.io

Next, update your phone number's SMS webhook. You can do this using the twilio-cli command-line tool, or through the Twilio Console on your web browser. The following sections will walkthrough each method.

To update your phone number's SMS webhook using the twilio-cli, just run the following CLI command in your terminal. Substitute <phone_number> with your Twilio phone number in E.164 format, and <forwarding_url> with the forwarding URL from ngrok.

twilio phone-numbers:update <phone_number> \
--sms-url=<forwarding_url>/sms \
--sms-method=POST

Alternatively, you can configure your SMS webhook on the Twilio Console in your web browser. To do this, Open the Twilio Console Phone Numbers tab, select your active phone number to open its Configurations page.

Once in the Configure page, under the Messaging Service section, set the A MESSAGE COMES IN URL field to the following, substituting the <forwarding_url> portion for the forwarding URL copied from ngrok's output:

<forwarding_url>/sms

It should look something like this:

https://1404-2601-282-1200-118-e1d0-ba12-d474-d43a.ngrok.io/sms

Next, click the Save button below in the Console to apply your Twilio messaging webhook URL.

After configuring your SMS webhook, start the application with the following commands, replacing <phone_number> with your Twilio phone number in E.164 format and <forwarding_url> with your ngrok forwarding URL:

./out/bin/sample-twilio-go -from=<phone_number> -url=<forwarding_url>

Your command should look something like this:

./out/bin/sample-twilio-go -from=+15555555555 -url=https://1404-2601-282-1200-118-e1d0-ba12-d474-d43a.ngrok.io

Interacting with the application

To initiate the review process, send an SMS message to your Twilio phone number.

After leaving a review, you may playback your review recording in the Twilio Console Call recordings tab by clicking the play icon for each call recording.

To view the total number of completed calls made by your application (and phone number), navigate to the http://localhost:8080/call-total page.

Further Configuration

The application uses Zap for structured, leveled logging. To configure the application's log level, set the -loglevel CLI option flag when starting the app to one of the following values (i.e. -loglevel=debug)

Value	Description
debug	Debug level logs (lowest level logs)
info	Info level logs (default)
warn	Warn level logs
error	Error level logs
panic	Panic level logs
fatal	Fatal level logs (highest level logs)

Getting help

For any questions or assistance regarding this application or the Twilio Go SDK, please feel free to reach out to us at our #help-dev-interfaces Slack channel.

For Twilio Go SDK documentation, examples, and code snippets, please refer to the documentation on pkg.go.dev/github.com/twilio/twilio-go.

Appendix

Code Areas of Interest

Areas of interest in the code base that serve as examples for using the Twilio SDK and troubleshooting errors.

Initializing the Twilio SDK client. A pointer to this client instance is then saved in each application's service client field for later use (i.e. SMSService.client)

https://github.com/twilio-labs/sample-twilio-go/blob/main/main.go#L44
Sending an SMS message with the SDK

https://github.com/twilio-labs/sample-twilio-go/blob/main/pkg/sms/sms_service.go#L102
Initiating a voice call with the SDK

https://github.com/twilio-labs/sample-twilio-go/blob/main/pkg/voice/voice_service.go#L38
Generating TwiML using the SDK

https://github.com/twilio-labs/sample-twilio-go/blob/main/pkg/message/message.go#L48
Initializing the SDK Request Validator. A pointer to this request validator instance is then saved in the application controller reqValidator field for later use (i.e. ReviewController.reqValidator)

https://github.com/twilio-labs/sample-twilio-go/blob/main/main.go#L64
Using the Request Validator to validate requests are coming from Twilio

https://github.com/twilio-labs/sample-twilio-go/blob/main/pkg/controller/review_controller.go#L153
Debugging errors returned in an API response while using the SDK

https://github.com/twilio-labs/sample-twilio-go/blob/main/pkg/sms/sms_service.go#L117

# README