James Wilson
9810406db2
* Prep to release 0.35 * Remove newline Co-authored-by: Niklas Adolfsson <niklasadolfsson1@gmail.com> * Fix a couple of small nits --------- Co-authored-by: Niklas Adolfsson <niklasadolfsson1@gmail.com>
parachain-example
This example showcases working with Subxt and Zombienet to try out connecting to a locally deployed parachain, here "Statemint", also known as "Asset Hub".
Running the example
1. Install zombienet
Zombienet is a tool for quickly spinning up a (local) blockchain network. We will use it to start up a local Asset Hub for us.
Please follow the install guide in the zombienet github repo to install it.
2. polkadot
We need a relay chain. Build the polkadot binary from the polkadot github repo and install it in your path:
git clone https://github.com/paritytech/polkadot.git
cd polkadot
cargo install --path .
3. polkadot-parachain
The Asset Hub is part of the cumulus github repo, an SDK for developing
parachains. Building the cumulus workspace produces a binary called polkadot-parachain which can be used to run
Asset Hub nodes.
git clone https://github.com/paritytech/cumulus.git
cd cumulus
cargo install --path polkadot-parachain
4. Run the parachain locally
With these binaries installed, Zombienet can now get the parachain running locally from a configuration file, asset-hub-zombienet.toml
in this case. We need to have at least 2 validator nodes running via the polkadot binary, and an Asset Hub node running via the
polkadot-parachain binary. Zombienet starts these up, and gets the parachain registered with the validator nodes for us. To do that,
run:
zombienet -p native spawn asset-hub-zombienet.toml
Zombienet uses Kubernetes by default, but we can use it without Kubernetes by providing the -p native flag.
You might have noticed that we use chain = "rococo-local" in the asset-hub-zombienet.toml file for the relay chain. This is just to
make the epoch time shorter and should have no effect on your interactions with the parachain. Polkadot / Kusama / Rococo have different
epoch times of 24h / 2h / 2min respectively.
5. Run the example
The parachain is only registered after the first epoch. So after the previous step, we need to wait 2 minutes until the parachain becomes interactive and produces blocks. At this point, we can run:
cargo run --bin parachain-example
To run our example code.
Dev notes
We can obtain the metadata for Statemint via the subxt cli tool, like so:
subxt metadata --url wss://polkadot-asset-hub-rpc.polkadot.io:443 > statemint_metadata.scale
It is important to explicitly specify the port as 443.
One way to find a suitable URL to obtain this from is by looking through the sidebar on Polkadot.js to find the Asset Hub entry, and seeing which RPC node URLs it uses.