Privacy-friendly feedback API

Why

We want to collect feedback from Users in a more privacy-friendly way, without collecting additional data or denying to do for 3rd parties.

What

Simple HTTPS API backend service, which will get data in JSON format and send it to an internal email (v1) to read.

Primary Use cases

1. Allow users of the Winden.app to leave extensive feedback
2. Allow users of the Winden.app to rate and leave small feedback after each successful transfer by the sender or receiver

Usage

This section describe how to directly compile and run the application assuming the Go programming language compiler is installed.

Alternatively the use of Docker Composer is described in the next section.

Build

The application can be build as follows:

go build

Run

The application directly compiled with Go can be started as follows:

./feedback-api \
-from "no-reply@example.com" \
-to foo@barbaz.com \
-smtp-server smtp.abc.xyz \
-smtp-port 465 \
-http-port 8001

As a result, an HTTP server should be listenning on localhost:8001 (CTRL+C to stop).

Configure

There are a few environment variables avaialble to configure the application:

• SMTP_HELO: To announce a valid client hostname when the SMTP client contacts the server.
• SMTP_USERNAME and SMTP_PASSWORD: To authenticate the SMTP client if the server supports it.
• SMTP_USE_TLS: Set to false to disable TLS, which can be useful if you want to use a dummy SMTP server for local development.
• SMTP_USE_INSECURE_TLS: Set to true to allow insecure TLS, which can be useful if you want to test with a self-sign certificate server in development env.

Example:

SMTP_HELO="gw.example.com" \
SMTP_USERNAME="foo@foobar.in" \
SMTP_PASSWORD="barbazquux" \
SMTP_USE_INSECURE_TLS=true \
./feedback-api \
-from "no-reply@example.com" \
-to foo@barbaz.com \
-smtp-server localhost

IMPORTANT: If you are using bash, before typing in the command above, type a SPC character, so that the above command carrying the username and password won't get into the bash history.

Test

Once the application in running, a POST request can be sent:

 curl \
--request POST \
--header "Content-Type: application/json" \
--data '{"feedback":{"title": "Full Feedback Form","rate": {"type" : "numbers","value" : 10},"questions":[{"question":"q1","answer":"a1"},{"question":"q2","answer":"a2"}]}}' \
http://localhost:8001/v1/feedback

REM: The JSON content needs to match the defined template!

Docker

To facilitate integration and testing, Docker Composer support is provided in this repo.

This also include a dummy SMTP server for testing purpose.

Requirements

• Docker (20.10.5+)
• Docker Composer (1.25.0+)

Configuration

This method relies exclusively on environment variables which means both the application parameters and the above described variables need to be defined in a local .env file (ignored by Git):

SMTP_FROM=no-reply@example.com
SMTP_TO=foo@barbaz.com
SMTP_SERVER=smtp.abc.xyz
SMTP_PORT=465
HTTP_PORT=8001

SMTP_HELO=http-server1.local
SMTP_USERNAME=foo@foobar.in
SMTP_PASSWORD=barbazquux
SMTP_USE_TLS=true
SMTP_USE_INSECURE_TLS=true

Usage

It is recommended to explicitly build the images at least once, then subsequently in case of changes on Docker config and/or images:

docker-compose [--compatibility] build

The following command should start the required services:

docker-compose [--compatibility] up

REM: Use the --compatibility switch (if supported) whenever resources need to be limitted (CPU and MEM).

From this point, the service(s) (http and smtp) should be running and ready to be tested (see curl command above).

Advanced Usage

If needed, Docker compose can also be used to start a single service.

For instance, here is how to run a standalone HTTP server w/o the SMTP service:

docker-compose [--compatibility] run \
--no-deps \
--rm \
--publish 8001:8001 \
-e SMTP_SERVER=smtp.example.com \
-e SMTP_PORT=465 \
-e SMTP_USE_TLS=true \
http-server1

Technical aspect

• Use JSON format RFC 8259