Add local parachain nodes

As you learned in Prepare a local relay chain, a parachain can work with a single collator.

Additional relay chain nodes

You should have at least two validators (relay chain nodes) running for every collator (parachain block authoring nodes) on your network.

You can modify the provided plain relay chain spec file to include more validators, or go the more "correct" route used for production of modifying the source for genesis state in chain_spec.rs for your relay chain to add more testnet validators at genesis. Recall how to generate chain specifications in the add trusted nodes tutorial.

Start a collator

Start the collator node

With chain spec in hand, you can now start the collator node. Notice that we need to supply the same relay chain chain spec we used for launching relay chain nodes at the second half of the command:

./target/release/parachain-collator \
--alice \
--collator \
--force-authoring \
--chain rococo-local-parachain-2000-raw.json \
--base-path /tmp/parachain/alice \
--port 40333 \
--rpc-port 8844 \
-- \
--execution wasm \
--chain <relay chain raw chain spec> \
--port 30343 \
--rpc-port 9977

Start a second collator

The command to run additional collators is as follows, assuming Alice node is running already. This command is nearly identical to the one we used to start the first collator, but we need to avoid conflicting ports and base-path directories:

./target/release/parachain-collator \
--bob \
--collator \
--force-authoring \
--chain rococo-local-parachain-2000-raw.json \
--base-path /tmp/parachain/bob \
--bootnodes <a running collator node> \
--port 40334 \
--rpc-port 9946 \
-- \
--execution wasm \
--chain <relay chain chain spec> \
--port 30344 \
--rpc-port 9978
--bootnodes <other relay chain node>

Related material

• Polkadot Wiki: Collator.
• Prepare a local relay chain tutorial.