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Build and run the Logos Blockchain UI app

Run a node that participates in consensus via a standalone application.​

The Logos Blockchain is the blockchain module of the Logos technology stack, providing a privacy-preserving and censorship-resistant framework for decentralised network states. You can run a Logos Blockchain node using the CLI or a standalone application.

info

For testnet v0.1, you must manually edit the config file and restart the node to add new keys.

Before you start, make sure you have the following:

  • A supported OS: Linux x86_64 or macOS

  • Nix with flakes enabled. Install from nixos.org, then enable flakes:

    mkdir -p ~/.config/nix
    echo 'experimental-features = nix-command flakes' >> ~/.config/nix/nix.conf

What to expect​

By the end of this tutorial:

  • You will have a Logos Blockchain node running and connected to peers.
  • Your wallet will hold testnet funds requested from the faucet.
  • Your node will be eligible to participate in the consensus lottery after the UTXO ages for approximately two hours.

Step 1: Run the Logos Blockchain app​

  1. Clone the repository:

    git clone https://github.com/logos-blockchain/logos-blockchain-ui.git
    cd logos-blockchain-ui

  2. Build and run the standalone app:

    nix run
    info

    On a cold Nix cache, the first run compiles the blockchain UI from source (Qt/C++ and Rust dependencies). This can take 20–60 minutes. Subsequent runs are instant from cache.

Step 2: Generate and load a node config​

  1. In the app, click Generate Config.

    Initial screen

  2. In the Logos Blockchain release notes, search for "testnet bootstrap peers" and copy the initial trusted peer set.

  3. In the app, paste the peer set information in the Initial peers and click Generate Config on the bottom.

  4. Click Load Config and select the generated config file.

  5. Click Start Node. A green indicator shows the node is running, and the wallet appears with a balance of 0.

    Running node

Step 3: Request testnet funds from the faucet​

  1. From the wallet section of the UI, copy one of your keys.

  2. Go to the testnet faucet, paste your key, and click Request Funds.

    info

    The transaction can take up to a minute to confirm and appear in your wallet.

Step 4: Verify the node is healthy​

  1. Check that the blockchain height is increasing:

    curl localhost:8080/cryptarchia/info

    Example response:

    {"lib":"3d0c...4e6d","tip":"f44d...e2f5","slot":70899,"height":120,"mode":"Bootstrapping"}

    Expect height to increase at an average rate of one block every 10 seconds. The timing is probabilistic, so some variance is normal.

  2. Check that the node is connected to peers:

    curl localhost:8080/network/info

    Example response:

    {"listen_addresses":["/ip4/127.0.0.1/udp/3001/quic-v1"],"peer_id":"12D3...fuS2","n_peers":16,"n_connections":19,"n_pending_connections":0}

    Confirm that n_peers is greater than 0.

Once the node is funded and the UTXO has aged for approximately two hours, the node automatically participates in the consensus lottery and starts producing blocks.

Troubleshooting starting a node​

The wallet balance does not update after a faucet request​

Only one faucet transaction can be included per block, so transactions may be dropped during periods of high demand. Retry the request from the faucet.

nix build is taking a long time to build​

This is expected behaviour. The build could take over an hour in some cases.