Node Modes

Yano (opens in a new tab) is a lightweight Cardano devnet node added in v0.12.0-beta5 to help DevKit bootstrap and run PV11-compatible local networks quickly.

Yaci DevKit currently exposes two primary Yano-backed modes through node.properties:

nodeMode=companion

or

nodeMode=yano-only

Why Yano Is Needed

Cardano node 11.0.1 validates the length of each Plutus cost model. That means DevKit can no longer patch extra cost model entries directly into genesis files for fast local startup.

Protocol parameter changes now need to go through the proper governance action flow. Yano helps DevKit complete that flow quickly during devnet bootstrap.

Companion Mode

companion is the default mode.

In companion mode, Yano bootstraps the devnet before handing over to the Haskell node.

Yano starts the network in the past, submits the required protocol parameter governance action for Plutus cost models, advances the chain until the update is enacted, and then fast-forwards back to wall-clock time before handover.

This avoids requiring users to wait for two epoch transitions before updated protocol parameters are available.

Use companion mode when you want normal Haskell-node behavior, including node socket access, but want DevKit to prepare the chain quickly for PV11 protocol parameters.

Yano-only Mode

In yano-only mode, Yano runs as the devnet node. There is no Haskell node handover.

Yaci Store syncs directly from Yano, so this mode starts quickly and avoids running a separate Cardano node process.

Use Yano-only mode when you want a lightweight devnet for application, SDK, and API testing and do not need direct Haskell node process or node socket access.

Configuration

For Docker and zip distributions, set the mode in config/node.properties before creating the devnet:

# Yano bootstraps, then Haskell node takes over
nodeMode=companion

# Yano runs as the only node
nodeMode=yano-only

After changing nodeMode, recreate the devnet:

yaci-cli:> create-node -o --start

Ports

When Yano is running, these ports are used by default:

For Docker, these can be changed in config/env:

HOST_YANO_HTTP_PORT=6060
HOST_YANO_N2N_PORT=14447

Run info in the Yaci CLI to see the active node mode and URLs for the current devnet.