The watch command (truss chains watch) combines the best of local development and full deployment. watch lets you run on an exact copy of the production hardware and interface but gives you live code patching that lets you test changes in seconds without creating a new deployment.

To use truss chains watch:

  1. Push a chain in development mode (i.e. publish and promote flags are false).
  2. Run the watch command truss chains watch SOURCE. You can also add the watch option to the push command and combine both to a single step.
  3. Each time you edit a file and save the changes, the watcher patches the remote deployments. Updating the deployments might take a moment, but is generally much faster than creating a new deployment.
  4. You can call the chain with test data via cURL or the playground dialogue in the UI and observe the result and logs.
  5. Iterate steps 3. and 4. until your chain behaves in the desired way.

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Selective Watch

Some large ML models might have a slow cycle time to reload (e.g. if the weights are huge). For this case, we provide a “selective” watch option. For example if you chain has such a heavy model Chainlet and other Chainlets that contain only business logic, you can iterate on those, while not patching and reloading the heavy model Chainlet.

This feature is really useful for advanced use case, but must be used with caution. If you change the code of a Chainlet not watched, in particular I/O types, you get an inconsistent deployment.

Add the Chainlet names you want to watch as a comma separated list:

truss chains watch ... --experimental-chainlet-names=ChainletA,ChainletB