Getting started

To get started quickly, let's walk you through our standard demo setup consisting of

• a cluster of three hydra-node, directly connected to each other, each having access to one of three Hydra credentials alice, bob, or carol;
• a single cardano-node producing blocks used as a (very fast) local devnet;
• the hydra-tui example clients to interact with the individual Hydra nodes.

This tutorial will be using Docker to install and the nodes, so make sure to have it installed. If you want to explore alternative ways of running the tools, see this tutorial variant or the testnet tutorial does use pre-built binaries, while documentation pages on installation and configuration provide more details.

Also, the hydra-tui does use the HTTP/WebSocket API provided by the hydra-node behind the scenes. The testnet tutorial will show how to use this API using low-level commands or see the API reference.

Video demonstration (a bit dated)

OS Compatibility

These instructions have been tested only on Linux environments (Ubuntu, NixOS). If you're on Windows or Mac OS X, you might need to adapt to use Volumes.

Preparation

All commands below are written as if executed from the demo folder in the project repository, so make sure to clone the repository, switch into the demo folder and pull the latest docker images:

git clone git@github.com:input-output-hk/hydra.git
cd hydra/demo
docker compose pull

Shortcut

For convenience, we also provide a script ./run-docker.sh, which combines all following steps. It also performs a few sanity checks to avoid tripping ourselves.

Set up the devnet

Next, we can run prepare the devnet configuration to bootstrap a local Cardano blockchain. Note that, we use a simple variant of Cardano that requires no stake pools whatsoever.

./prepare-devnet.sh

We can now bring the Cardano node up with:

docker compose up -d cardano-node

You can verify that the devnet is up-and-running by checking the logs with:

docker compose logs cardano-node -f

You should see traces containing TraceAdoptedBlock, which means that the devnet is producing blocks .. nice!

info

Don't wait too long between these two commands. If you get TraceNoLedgerView errors from the Cardano node, the genesis start time is too far in the past and you need to update them by running prepare-devnet.sh again.

Next we need to give Alice, Bob, and Carol some UTxOs to commit and some ADA to pay fees. We include a script seed-devnet.sh that uses the cardano-cli in the already running cardano-node container to do that:

./seed-devnet.sh

Start Hydra nodes

Finally, now that the on-chain preparations are done, we can bring the Hydra network (all three nodes for Alice, Bob and Carol) up by running:

docker compose up -d hydra-node-{1,2,3}

Using compose, you can start the demo Terminal-based User Interface (a.k.a. hydra-tui) to interact with Hydra nodes. There are 3 preconfigured TUI services in the compose definition: hydra-tui-1, hydra-tui-2, and hydra-tui-3. To connect to the first Hydra node in a terminal, run the following command:

docker compose run hydra-tui-1

This will start a full-blown terminal interface loaded with signing keys corresponding to the first Hydra node. In other terminals, you can start other nodes in a similar fashion targeting hydra-tui-2 and hydra-tui-3 services.

Use the head

Using the terminal interface of any node, you can now [i]nit the Hydra head and [c]ommit pre-distributed funds to it. Note that these steps are near instant as the devnet is producing blocks much faster than a public testnet or the mainnet. After committing from all nodes, the head will automatically open and you can also use the hydra-tui or the API to create new transactions and submit them to the Hydra head.