A regtest demo

Our software is experimental and it is reckless to run it with real bitcoin.

Bitcoin Core provides a few other networks that can be used to test new functionality. In this scenario we are going to use regtest.

Setting up a regtest environment

Ensure you have installed all optional dependencies described in compile from source. Go to root of the repository and source the ark_demo.sh file.

source ark_demo.sh

This creates a good environment to play with bark and aspd. We start with setting up a regtest bitcoin-node. If you already have a node running you can use that one. You just have to ensure that txindex is enabled.

For the purpose of this tutorial it is easier to spin up a new regtest node. The ark_demo.sh script has created a handy alias bd

bd --daemon

You can always use type -a bd to see what the alias does. In this case it will tell you that bd is an alias for bitcoind -regtest -datadir=/ark/test/bitcoindatadir -server -txdindex -fallbackfee=0.0002.

You can use the bitcoin-cli which is aliased to bcli to interact with the node.

bcli getnetworkinfo

Testing bitcoin without coins isn't fun. We add a wallet to Bitcoin Core and send some funds to it. We mine some blocks and reap the rewards.

It is good to verify

bcli createwallet "default"
bcli -generate 106
bcli getbalance

Then we create and configure an ark-server using the aspd-command. Our ark-server will run on regtest and use the bitcoin-node we've started a few lines before.

aspd create \
    --network regtest \
    --datadir ./test/arkdatadir \
    --bitcoind-url $BITCOIND_URL \
    --bitcoind-cookie $BITCOIND_COOKIE

The server can be started using

aspd start --datadir ./test/arkdatadir

The server will start working immediately but requires some funds. We can get the address and some funds to it. You can get the address using the following rpc command.

aspd rpc get-address

We can now send 100 BTC to the asp

bcli sendtoaddress <asp-addr> 100

and check if the aspd received the money

aspd rpc balance

Next, you can start some clients. To create a client, use the following command:

bark --datadir ./test/bark1 create \
    --regtest \
    --asp http://localhost:3535 \
    --bitcoind $BITCOIND_URL \
    --bitcoind-cookie $BITCOIND_COOKIE

bark --datadir ./test/bark2 create \
    --regtest \
    --asp http://localhost:3535 \
    --bitcoind $BITCOIND_URL \
    --bitcoind-cookie $BITCOIND_COOKIE

Note that clients can receive off-chain Ark transactions without having any on-chain balance, but a little bit of on-chain money is needed to perform unilateral exits.

You can fund the wallet using

BARK1_ADDR=$(bark --datadir ./test/bark1 onchain address)
bcli sendtoaddress $BARK1_ADDR 5

To use the onchain wallets, there are a few commands available:

BARK2_ADDR=$(bark --datadir ./test/bark2 onchain address)
bark --datadir ./test/bark1 onchain send $BARK2_ADDR "0.1 btc"
bark --datadir ./test/bark2 onchain balance

Once we have money, we can onboard into the Ark, afterwards the balance will also show an off-chain element.

bark --datadir ./test/bark1 onboard "1 btc"
bark --datadir ./test/bark1 balance

Remember that all txs will just be in the mempool if you don't generate blocks once a while...

bcli -generate 1

Then, let's send some money off-chain:

## Should be empty..
BARK2_PK=$(bark --datadir ./test/bark2 vtxo-pubkey)
# For now every client has just a single pubkey.
echo "${BARK2_PK}"
bark --datadir ./test/bark1 send-round ${BARK2_PK} "0.1 btc"
bark --datadir ./test/bark2 balance

You will notice that there is a slight delay when sending, this is because the client needs to wait for the start of the next round.

However, you can also pay out-of-round. These payments work instantly.

## Should be empty..
BARK2_PK2=$(bark --datadir ./test/bark2 vtxo-pubkey)
# For now every client has just a single pubkey.
echo "${BARK2_PK2}"
bark --datadir ./test/bark1 send ${BARK2_PK2} "0.1 btc"
bark --datadir ./test/bark2 balance