This module simulates a Transaction Server for registering, updating, notifying slack, and listing transactions using GenServer

It will start as soon as our vhs app started

At the moment of developing this project, I used the following versions of Elixir and Erlang.

iex> mix hex.info

Hex:    0.21.2
Elixir: 1.12.2
OTP:    24.0.4

Built with: Elixir 1.11.4 and OTP 21.3

• POST /blocknative/confirm to watch transaction hash

   // Request body params to be sent
   { 
      "hash": "0x51d49ccc52e0d00941f86a1bd67e020162a6e1041b4e904ecdae03ebf0f1a907"
   }

• POST /blocknative/webhook webhook url to receive transaction updates

• POST /blocknative/transactions/pending to list the all pending transactions

  // response
  {
    "data": [
        {
            "hash": "0x51d49ccc52e0d00941f86a1bd67e020162a6e1041b4e904ecdae03ebf0f1a907",
            "status": "pending"
        }
    ],
    "status": "ok"
  }

Add .env file with following environment variables

BLOCKNATIVE_API_KEY="<key>"
SLACK_WEBHOOK_KEY=""

After that just build and run using the following commands

docker build -t vhs .
docker run -t vhs

By default visit 172.17.0.2:4000/blocknative/transactions/pending

mix deps.get
mix release vhs

I added the releases path to ./releases

So, we are provided with following commands.

Release created at releases!

    # To start your system
    releases/bin/vhs start

Once the release is running:

    # To connect to it remotely
    releases/bin/vhs remote

    # To stop it gracefully (you may also send SIGINT/SIGTERM)
    releases/bin/vhs stop

To list all commands:

    releases/bin/vhs

visit localhost:4000/blocknative/transactions/pending

Running Interactively

The ngrok will allow local webserver running to internet. So, we can use our local webserver url as webhook url at blocknative.

run the following command

ngrok http 4000

You will see the following output.

Session Status                online
Version                       2.3.40
Region                        United States (us)
Web Interface                 http://127.0.0.1:4040
Forwarding                    http://14fc-136-185-52-176.ngrok.io -> http://localhost:4000
Forwarding                    https://14fc-136-185-52-176.ngrok.io -> http://localhost:4000
Connections                   ttl     opn     rt1     rt5     p50     p90

The urls may look different as ngrok assigns random hexadecimal names to the HTTP tunnels it opens.
Here the url is http://14fc-136-185-52-176.ngrok.io which will act our webhook base.

Make sure you add http://14fc-136-185-52-176.ngrok.io/blocknative/webhook as webhook url for blocknative.

• API Integration (Blocknative) Implementation
• Transaction Server callbacks for updating the transaction status.
• Using docker to releases with Elixir.

• Learned how to use localhost web server as webhook using ngrok
• Docker setup for Elixir projects with releases

I felt it is a well framed to test core concepts of Elixir as project made me to code in all the core concepts of Elixir like GenServers, Enumaration, collections, webhooks.

I really enjoyed coding webhooks, playing with docker, and notifying over slack.

Thank You :)

Best Regards, Ankanna