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Install Local Binaries

This page will focus on installing the dependencies you need to run a local relay chain. You will:

  • Install polkadot
  • Configure a valid chain specification for your relay chain

Prerequisites​

Before starting, you should have the following already on your system:

  1. Rust Toolchain
  2. git

For more information, view the General Prerequisites page.

For the best experience in following this guide, consider also cloning this repository: parachain-guide-resources

Installing polkadot​

For this guide, we will ensure a consistent environment by installing Polkadot. This is how we will provision and start our relay chain instance:

If you are on macOS, below is the current best way to install polkadot:

  1. Clone the latest, stable branch of Polkadot (1.0.0 at the time of this writing):

    git clone --branch release-v1.0.0 https://github.com/paritytech/polkadot.git

  2. Use cargo to build the binary

    cargo build --release
    ⌛ This will take some time

    Depending on your machine, this may take 45-60 minutes.

  3. Once compiled, ensure it runs:

    ./target/release/polkadot --help
Create a symlink to easily run your Polkadot binary.

For ease of use, consider adding the target executable to your local path or creating a symlink. There are three binaries that need to be linked if you choose to do this:

  • polkadot
  • polkadot-execute-worker
  • polkadot-prepare-worker
# Replace <path> with the path to your cloned polkadot repo
# The last line may need to be replaced!

# Polkadot
ln -s <path-to-polkadot>/target/release/polkadot /usr/local/bin/polkadot

# Polkadot Prepare Worker
ln -s <path-to-polkadot>/target/release/polkadot-prepare-worker /usr/local/bin/polkadot-prepare-worker

# Polkadot Execute Worker
ln -s <path-to-polkadot>/target/release/polkadot-execute-worker /usr/local/bin/polkadot-execute-worker

# Use directly in path!

polkadot --help

Option 2: Install via a package manager (Linux)​

One may use apt to install the polkadot binary. You may find instructions for this on the Polkadot Wiki.

Chain Specification​

This is optional!

Generating a new chain specification should only be done if you want to run the relay chain with your own modification. It is recommended that you skip this and come back to it later if you decide to change how the relay chain implementation works, or wish to try out different configs.

For development purposes, it is recommended that you use the chain specification included within parachain-guide-resources.

Once Polkadot is compiled, we must ensure we have a valid chain_spec file to launch our local relay chain.

For the purposes of this guide, you can use the one located here with your cloned repository at relaychain/relaychain_chain_spec.json and relaychain/relaychain_chain_spec_raw.json and. Keep this at hand, as this will be used to run your relay chain.

Optional: Generating a Custom Chain Specification​

It is possible to also generate your own, custom chain specification. This is usually done after changing the polkadot source code, as the code field within the chain spec would need to be updated. Once you modify the chain spec, you can run the following command to generate it:

# Run from locally compiled repository
./target/debug/polkadot build-spec > ./relaychain/my_relaychain_spec.json
# or, with symlink
polkadot build-spec > ./relaychain/my_relaychain_spec.json

Once this is built, also build the raw, SCALE-encoded file:

# Run from locally compiled repository
./target/debug/polkadot build-spec \
    --chain ./relaychain/my_relaychain_spec.json \
    --raw > ./relaychain/my_relaychain_spec_raw.json

# or, with symlink
polkadot build-spec \
    --chain ./relaychain/my_relaychain_spec.json \
    --raw > ./relaychain/my_relaychain_spec_raw.json