#Launching a Testnet

#Step 1: Start Docker Testnet Database

You already generated docker files during the development environment setup (if not please run the following commands as specified here).

1cd core/docker/development/testnet #testnet docker folder
2docker-compose up -d postgres #start postgres testnet container

#Step 2: Testnet Network Boot

Let’s jump to the core/packages/core and start our first testnet with the commands below:

1cd core/packages/core
2yarn full:testnet #run the testnet blockchain on your local computer

After executing the yarn full:testnet command you should see something like this in your command prompt:

 1yarn run v1.22.10
 2$ cross-env CORE_PATH_CONFIG=./bin/config/testnet yarn ark core:run --networkStart --env=test
 3$ node ./bin/run core:run --networkStart --env=test
 4The jemalloc library was not found on your system. It is recommended to install it for better memory management. Falling back to the system default...
 5[2021-07-07 13:42:17.512] INFO : Connecting to database: ark_testnet
 6[2021-07-07 13:42:18.109] INFO : P2P Server started at http://127.0.0.1:4000
 7[2021-07-07 13:42:18.110] INFO : Starting Blockchain Manager
 8[2021-07-07 13:42:18.115] INFO : Verifying database integrity
 9[2021-07-07 13:42:18.149] INFO : Verified database integrity
10[2021-07-07 13:42:18.159] INFO : Last block in database: 892
11[2021-07-07 13:42:18.160] INFO : State Generation - Step 1 of 26: Block Rewards
12[2021-07-07 13:42:18.169] INFO : State Generation - Step 2 of 26: Fees & Nonces
13...

This means that you core node is now running and simulating a blockchain on your local computer.

#Step 3: Your First API Call

With our testnet up and running, the first thing we need to do is connect to it. All interactions between ARK Nodes and the outside world happen through the Public API, which is a REST API facilitating different actions on the blockchain.

It is possible to interact with a node directly through HTTP without using any programming language at all. By default, the Public API for testnet opens a connection on your local machine at http://0.0.0.0:4003/api. We can check out newly forged blocks in our browser with a running testnet. You should see a response showing you all the (empty) blocks your testnet forgers have recently created.

Let’s try to retrieve the latest block and supply by calling the GET api/blockchain endpoint with curl. Run the following request from console via curl command or via browser.

Request:

1curl http://127.0.0.1:4003/api/blockchain

We should get the following response:

1{
2    "data": {
3        "block": {
4            "height": 145,
5            "id": "17498538834395765847"
6        },
7        "supply": "12500000000000000"
8    }
9}

Your core server is now running and responding to your requests. Look at the Public REST API and play with some requests so you get a better feel for how things run. Try some of the following endpoints:

1. Retrieve Node Configuration
2. Retrieve The Cryptography Configuration
3. List All Transactions
4. Explore more endpoints