Substrate Cumulus Parachain Template

A new Cumulus-based Substrate node, ready for hacking ☁️

This project is a fork of the Substrate Node Template modified to include dependencies required for registering this node as a parathread or parachain to an established relay chain.

👉 Learn more about parachains here, and parathreads here.

Build & Run

Follow these steps to prepare a local Substrate development environment 🛠️

Setup of Machine

If necessary, refer to the setup instructions at the Substrate Developer Hub.

Build

Once the development environment is set up, build the Cumulus Parachain Template. This command will build the Wasm Runtime and native code:

cargo build --release

Relay Chain

NOTE: In the following two sections, we document how to manually start a few relay chain nodes, start a parachain node (collator), and register the parachain with the relay chain.

We also have the polkadot-launch CLI tool that automate the following steps and help you easily launch relay chains and parachains. However it is still good to go through the following procedures once to understand the mechanism for running and registering a parachain.

To operate a parathread or parachain, you must connect to a relay chain. Typically you would test on a local Rococo development network, then move to the testnet, and finally launch on the mainnet. Keep in mind you need to configure the specific relay chain you will connect to in your collator chain_spec.rs. In the following examples, we will use rococo-local as the relay network.

Build Relay Chain

Clone and build Polkadot (beware of the version tag we used):

# Get a fresh clone, or `cd` to where you have polkadot already:
git clone -b v0.9.7 --depth 1 https://github.com/paritytech/polkadot.git
cd polkadot
cargo build --release

Generate the Relay Chain Chainspec

First, we create the chain specification file (chainspec). Note the chainspec file must be generated on a single node and then shared among all nodes!

👉 Learn more about chain specification here.

./target/release/polkadot build-spec \
--chain rococo-local \
--raw \
--disable-default-bootnode \
> rococo_local.json

Start Relay Chain

We need n + 1 full validator nodes running on a relay chain to accept n parachain / parathread connections. Here we will start two relay chain nodes so we can have one parachain node connecting in later.

From the Polkadot working directory:

# Start Relay `Alice` node
./target/release/polkadot \
--chain ./rococo_local.json \
-d /tmp/relay/alice \
--validator \
--alice \
--port 50555

Open a new terminal, same directory:

# Start Relay `Bob` node
./target/release/polkadot \
--chain ./rococo_local.json \
-d /tmp/relay/bob \
--validator \
--bob \
--port 50556

Add more nodes as needed, with non-conflicting ports, DB directories, and validator keys (--charlie, --dave, etc.).

Reserve a ParaID

To connect to a relay chain, you must first _reserve a ParaId for your parathread that will become a parachain. To do this, you will need sufficient amount of currency on the network account to reserve the ID.

In this example, we will use Charlie development account where we have funds available. Once you submit this extrinsic successfully, you can start your collators.

The easiest way to reserve your ParaId is via Polkadot Apps UI under the Parachains -> Parathreads tab and use the + ParaID button.

Parachain

Select the Correct Relay Chain

To operate your parachain, you need to specify the correct relay chain you will connect to in your collator chain_spec.rs. Specifically you pass the command for the network you need in the Extensions of your ChainSpec::from_genesis() in the code.

Extensions {
	relay_chain: "rococo-local".into(), // You MUST set this to the correct network!
	para_id: id.into(),
},

You can choose from any pre-set runtime chainspec in the Polkadot repo, by referring to the cli/src/command.rs and node/service/src/chain_spec.rs files or generate your own and use that. See the Cumulus Workshop for how.

In the following examples, we will use the rococo-local relay network we setup in the last section.

Export the Parachain Genesis and Runtime

We first generate the genesis state and genesis wasm needed for the parachain registration.

# Build the parachain node (from it's top level dir)
cd substrate-parachain-template
cargo build --release

# Folder to store resource files needed for parachain registration
mkdir -p resources

# Build the chainspec
./target/release/parachain-collator build-spec \
--disable-default-bootnode > ./resources/template-local-plain.json

# Build the raw chainspec file
./target/release/parachain-collator build-spec \
--chain=./resources/template-local-plain.json \
--raw --disable-default-bootnode > ./resources/template-local-raw.json

# Export genesis state to `./resources`, using 2000 as the ParaId
./target/release/parachain-collator export-genesis-state --parachain-id 2000 > ./resources/para-2000-genesis

# Export the genesis wasm
./target/release/parachain-collator export-genesis-wasm > ./resources/para-2000-wasm

NOTE: we have set the para_ID to be 2000 here. This must be unique for all parathreads/chains on the relay chain you register with. You must reserve this first on the relay chain for the testnet or mainnet.

Start a Parachain Node (Collator)

From the parachain template working directory:

# NOTE: this command assumes the chain spec is in a directory named `polkadot`
# that is at the same level of the template working directory. Change as needed.
#
# It also assumes a ParaId of 2000. Change as needed.
./target/release/parachain-collator \
-d /tmp/parachain/alice \
--collator \
--alice \
--force-authoring \
--ws-port 9945 \
--parachain-id 2000 \
-- \
--execution wasm \
--chain ../polkadot/rococo_local.json

Output:

2021-05-30 16:57:39 Parachain Collator Template
2021-05-30 16:57:39 ✌️  version 3.0.0-acce183-x86_64-linux-gnu
2021-05-30 16:57:39 ❤️  by Anonymous, 2017-2021
2021-05-30 16:57:39 📋 Chain specification: Local Testnet
2021-05-30 16:57:39 🏷 Node name: Alice
2021-05-30 16:57:39 👤 Role: AUTHORITY
2021-05-30 16:57:39 💾 Database: RocksDb at /tmp/parachain/alice/chains/local_testnet/db
2021-05-30 16:57:39 ⛓  Native runtime: template-parachain-1 (template-parachain-0.tx1.au1)
2021-05-30 16:57:41 Parachain id: Id(2000)
2021-05-30 16:57:41 Parachain Account: 5Ec4AhPUwPeyTFyuhGuBbD224mY85LKLMSqSSo33JYWCazU4
2021-05-30 16:57:41 Parachain genesis state: 0x0000000000000000000000000000000000000000000000000000000000000000000a96f42b5cb798190e5f679bb16970905087a9a9fc612fb5ca6b982b85783c0d03170a2e7597b7b7e3d84c05391d139a62b157e78786d8c082f29dcf4c11131400
2021-05-30 16:57:41 Is collating: yes
2021-05-30 16:57:41 [Parachain] 🔨 Initializing Genesis block/state (state: 0x0a96…3c0d, header-hash: 0xd42b…f271)
2021-05-30 16:57:41 [Parachain] ⏱  Loaded block-time = 12s from block 0xd42bb78354bc21770e3f0930ed45c7377558d2d8e81ca4d457e573128aabf271
2021-05-30 16:57:43 [Relaychain] 🔨 Initializing Genesis block/state (state: 0xace1…1b62, header-hash: 0xfa68…cf58)
2021-05-30 16:57:43 [Relaychain] 👴 Loading GRANDPA authority set from genesis on what appears to be first startup.
2021-05-30 16:57:44 [Relaychain] ⏱  Loaded block-time = 6s from block 0xfa68f5abd2a80394b87c9bd07e0f4eee781b8c696d0a22c8e5ba38ae10e1cf58
2021-05-30 16:57:44 [Relaychain] 👶 Creating empty BABE epoch changes on what appears to be first startup.
2021-05-30 16:57:44 [Relaychain] 🏷 Local node identity is: 12D3KooWBjYK2W4dsBfsrFA9tZCStb5ogPb6STQqi2AK9awXfXyG
2021-05-30 16:57:44 [Relaychain] 📦 Highest known block at #0
2021-05-30 16:57:44 [Relaychain] 〽️ Prometheus server started at 127.0.0.1:9616
2021-05-30 16:57:44 [Relaychain] Listening for new connections on 127.0.0.1:9945.
2021-05-30 16:57:44 [Parachain] Using default protocol ID "sup" because none is configured in the chain specs
2021-05-30 16:57:44 [Parachain] 🏷 Local node identity is: 12D3KooWADBSC58of6ng2M29YTDkmWCGehHoUZhsy9LGkHgYscBw
2021-05-30 16:57:44 [Parachain] 📦 Highest known block at #0
2021-05-30 16:57:44 [Parachain] Unable to listen on 127.0.0.1:9945
2021-05-30 16:57:44 [Parachain] Unable to bind RPC server to 127.0.0.1:9945. Trying random port.
2021-05-30 16:57:44 [Parachain] Listening for new connections on 127.0.0.1:45141.
2021-05-30 16:57:45 [Relaychain] 🔍 Discovered new external address for our node: /ip4/192.168.42.204/tcp/30334/ws/p2p/12D3KooWBjYK2W4dsBfsrFA9tZCStb5ogPb6STQqi2AK9awXfXyG
2021-05-30 16:57:45 [Parachain] 🔍 Discovered new external address for our node: /ip4/192.168.42.204/tcp/30333/p2p/12D3KooWADBSC58of6ng2M29YTDkmWCGehHoUZhsy9LGkHgYscBw
2021-05-30 16:57:48 [Relaychain] ✨ Imported #8 (0xe60b…9b0a)
2021-05-30 16:57:49 [Relaychain] 💤 Idle (2 peers), best: #8 (0xe60b…9b0a), finalized #5 (0x1e6f…567c), ⬇ 4.5kiB/s ⬆ 2.2kiB/s
2021-05-30 16:57:49 [Parachain] 💤 Idle (0 peers), best: #0 (0xd42b…f271), finalized #0 (0xd42b…f271), ⬇ 2.0kiB/s ⬆ 1.7kiB/s
2021-05-30 16:57:54 [Relaychain] ✨ Imported #9 (0x1af9…c9be)
2021-05-30 16:57:54 [Relaychain] ✨ Imported #9 (0x6ed8…fdf6)
2021-05-30 16:57:54 [Relaychain] 💤 Idle (2 peers), best: #9 (0x1af9…c9be), finalized #6 (0x3319…69a2), ⬇ 1.8kiB/s ⬆ 0.5kiB/s
2021-05-30 16:57:54 [Parachain] 💤 Idle (0 peers), best: #0 (0xd42b…f271), finalized #0 (0xd42b…f271), ⬇ 0.2kiB/s ⬆ 0.2kiB/s
2021-05-30 16:57:59 [Relaychain] 💤 Idle (2 peers), best: #9 (0x1af9…c9be), finalized #7 (0x5b50…1e5b), ⬇ 0.6kiB/s ⬆ 0.4kiB/s
2021-05-30 16:57:59 [Parachain] 💤 Idle (0 peers), best: #0 (0xd42b…f271), finalized #0 (0xd42b…f271), ⬇ 0 ⬆ 0
2021-05-30 16:58:00 [Relaychain] ✨ Imported #10 (0xc9c9…1ca3)

You see messages are from both a relaychain node and a parachain node. This is because a relay chain light client is also run next to the parachain collator.

Parachain Registration

Now that you have two relay chain nodes, and a parachain node accompanied with a relay chain light client running, the next step is to register the parachain in the relay chain with the following steps (for detail, refer to the Substrate Cumulus Worship):

• Goto Polkadot Apps UI, connecting to your relay chain.

• Execute a sudo extrinsic on the relay chain by going to Developer -> sudo page.

• Pick paraSudoWrapper -> sudoScheduleParaInitialize(id, genesis) as the extrinsic type, shown below.

  

• Set the id: ParaId to 2,000 (or whatever ParaId you used above), and set the parachain: Bool option to Yes.

• For the genesisHead, drag the genesis state file exported above, para-2000-genesis, in.

• For the validationCode, drag the genesis wasm file exported above, para-2000-wasm, in.

Note: When registering to the public Rococo testnet, ensure you set a unique paraId larger than 1,000. Values below 1,000 are reserved exclusively for system parachains.

Restart the Parachain (Collator)

The collator node may need to be restarted to get it functioning as expected. After a new epoch starts on the relay chain, your parachain will come online. Once this happens, you should see the collator start reporting parachain blocks:

# Notice the relay epoch change! Only then do we start parachain collating!
#
2021-05-30 17:00:04 [Relaychain] 💤 Idle (2 peers), best: #30 (0xfc02…2a2a), finalized #28 (0x10ff…6539), ⬇ 1.0kiB/s ⬆ 0.3kiB/s
2021-05-30 17:00:04 [Parachain] 💤 Idle (0 peers), best: #0 (0xd42b…f271), finalized #0 (0xd42b…f271), ⬇ 0 ⬆ 0
2021-05-30 17:00:06 [Relaychain] 👶 New epoch 3 launching at block 0x68bc…0605 (block slot 270402601 >= start slot 270402601).
2021-05-30 17:00:06 [Relaychain] 👶 Next epoch starts at slot 270402611
2021-05-30 17:00:06 [Relaychain] ✨ Imported #31 (0x68bc…0605)
2021-05-30 17:00:06 [Parachain] Starting collation. relay_parent=0x68bcc93d24a31a2c89800a56c7a2b275fe9ca7bd63f829b64588ae0d99280605 at=0xd42bb78354bc21770e3f0930ed45c7377558d2d8e81ca4d457e573128aabf271
2021-05-30 17:00:06 [Parachain] 🙌 Starting consensus session on top of parent 0xd42bb78354bc21770e3f0930ed45c7377558d2d8e81ca4d457e573128aabf271
2021-05-30 17:00:06 [Parachain] 🎁 Prepared block for proposing at 1 [hash: 0xf6507812bf60bf53af1311f775aac03869be870df6b0406b2969784d0935cb92; parent_hash: 0xd42b…f271; extrinsics (2): [0x1bf5…1d76, 0x7c9b…4e23]]
2021-05-30 17:00:06 [Parachain] 🔖 Pre-sealed block for proposal at 1. Hash now 0x80fc151d7ccf228b802525022b6de257e42388ec7dc3c1dd7de491313650ccae, previously 0xf6507812bf60bf53af1311f775aac03869be870df6b0406b2969784d0935cb92.
2021-05-30 17:00:06 [Parachain] ✨ Imported #1 (0x80fc…ccae)
2021-05-30 17:00:06 [Parachain] Produced proof-of-validity candidate. block_hash=0x80fc151d7ccf228b802525022b6de257e42388ec7dc3c1dd7de491313650ccae
2021-05-30 17:00:09 [Relaychain] 💤 Idle (2 peers), best: #31 (0x68bc…0605), finalized #29 (0xa6fa…9e16), ⬇ 1.2kiB/s ⬆ 129.9kiB/s
2021-05-30 17:00:09 [Parachain] 💤 Idle (0 peers), best: #0 (0xd42b…f271), finalized #0 (0xd42b…f271), ⬇ 0 ⬆ 0
2021-05-30 17:00:12 [Relaychain] ✨ Imported #32 (0x5e92…ba30)
2021-05-30 17:00:12 [Relaychain] Moving approval window from session 0..=2 to 0..=3
2021-05-30 17:00:12 [Relaychain] ✨ Imported #32 (0x8144…74eb)
2021-05-30 17:00:14 [Relaychain] 💤 Idle (2 peers), best: #32 (0x5e92…ba30), finalized #29 (0xa6fa…9e16), ⬇ 1.4kiB/s ⬆ 0.2kiB/s
2021-05-30 17:00:14 [Parachain] 💤 Idle (0 peers), best: #0 (0xd42b…f271), finalized #0 (0xd42b…f271), ⬇ 0 ⬆ 0
2021-05-30 17:00:18 [Relaychain] ✨ Imported #33 (0x8c30…9ccd)
2021-05-30 17:00:18 [Parachain] Starting collation. relay_parent=0x8c30ce9e6e9867824eb2aff40148ac1ed64cf464f51c5f2574013b44b20f9ccd at=0x80fc151d7ccf228b802525022b6de257e42388ec7dc3c1dd7de491313650ccae
2021-05-30 17:00:19 [Relaychain] 💤 Idle (2 peers), best: #33 (0x8c30…9ccd), finalized #30 (0xfc02…2a2a), ⬇ 0.7kiB/s ⬆ 0.4kiB/s
2021-05-30 17:00:19 [Parachain] 💤 Idle (0 peers), best: #1 (0x80fc…ccae), finalized #0 (0xd42b…f271), ⬇ 0 ⬆ 0
2021-05-30 17:00:22 [Relaychain] 👴 Applying authority set change scheduled at block #31
2021-05-30 17:00:22 [Relaychain] 👴 Applying GRANDPA set change to new set [(Public(88dc3417d5058ec4b4503e0c12ea1a0a89be200fe98922423d4334014fa6b0ee (5FA9nQDV...)), 1), (Public(d17c2d7823ebf260fd138f2d7e27d114c0145d968b5ff5006125f2414fadae69 (5GoNkf6W...)), 1)]
2021-05-30 17:00:22 [Relaychain] 👴 Imported justification for block #31 that triggers command Changing authorities, signaling voter.
2021-05-30 17:00:24 [Relaychain] ✨ Imported #34 (0x211b…febf)
2021-05-30 17:00:24 [Parachain] Starting collation. relay_parent=0x211b3c53bebeff8af05e8f283d59fe171b7f91a5bf9c4669d88943f5a42bfebf at=0x80fc151d7ccf228b802525022b6de257e42388ec7dc3c1dd7de491313650ccae
2021-05-30 17:00:24 [Parachain] 🙌 Starting consensus session on top of parent 0x80fc151d7ccf228b802525022b6de257e42388ec7dc3c1dd7de491313650ccae
2021-05-30 17:00:24 [Parachain] 🎁 Prepared block for proposing at 2 [hash: 0x10fcb3180e966729c842d1b0c4d8d2c4028cfa8bef02b909af5ef787e6a6a694; parent_hash: 0x80fc…ccae; extrinsics (2): [0x4a6c…1fc6, 0x6b84…7cea]]
2021-05-30 17:00:24 [Parachain] 🔖 Pre-sealed block for proposal at 2. Hash now 0x5087fd06b1b73d90cfc3ad175df8495b378fffbb02fea212cc9e49a00fd8b5a0, previously 0x10fcb3180e966729c842d1b0c4d8d2c4028cfa8bef02b909af5ef787e6a6a694.
2021-05-30 17:00:24 [Parachain] ✨ Imported #2 (0x5087…b5a0)
2021-05-30 17:00:24 [Parachain] Produced proof-of-validity candidate. block_hash=0x5087fd06b1b73d90cfc3ad175df8495b378fffbb02fea212cc9e49a00fd8b5a0
2021-05-30 17:00:24 [Relaychain] 💤 Idle (2 peers), best: #34 (0x211b…febf), finalized #31 (0x68bc…0605), ⬇ 1.0kiB/s ⬆ 130.1kiB/s
2021-05-30 17:00:24 [Parachain] 💤 Idle (0 peers), best: #1 (0x80fc…ccae), finalized #0 (0xd42b…f271), ⬇ 0 ⬆ 0
2021-05-30 17:00:29 [Relaychain] 💤 Idle (2 peers), best: #34 (0x211b…febf), finalized #32 (0x5e92…ba30), ⬇ 0.2kiB/s ⬆ 0.1kiB/s
2021-05-30 17:00:29 [Parachain] 💤 Idle (0 peers), best: #1 (0x80fc…ccae), finalized #0 (0xd42b…f271), ⬇ 0 ⬆ 0
2021-05-30 17:00:30 [Relaychain] ✨ Imported #35 (0xee07…38a0)
2021-05-30 17:00:34 [Relaychain] 💤 Idle (2 peers), best: #35 (0xee07…38a0), finalized #33 (0x8c30…9ccd), ⬇ 0.9kiB/s ⬆ 0.3kiB/s
2021-05-30 17:00:34 [Parachain] 💤 Idle (0 peers), best: #1 (0x80fc…ccae), finalized #1 (0x80fc…ccae), ⬇ 0 ⬆ 0
2021-05-30 17:00:36 [Relaychain] ✨ Imported #36 (0xe8ce…4af6)
2021-05-30 17:00:36 [Parachain] Starting collation. relay_parent=0xe8cec8015c0c7bf508bf3f2f82b1696e9cca078e814b0f6671f0b0d5dfe84af6 at=0x5087fd06b1b73d90cfc3ad175df8495b378fffbb02fea212cc9e49a00fd8b5a0
2021-05-30 17:00:39 [Relaychain] 💤 Idle (2 peers), best: #36 (0xe8ce…4af6), finalized #33 (0x8c30…9ccd), ⬇ 0.6kiB/s ⬆ 0.1kiB/s
2021-05-30 17:00:39 [Parachain] 💤 Idle (0 peers), best: #2 (0x5087…b5a0), finalized #1 (0x80fc…ccae), ⬇ 0 ⬆ 0

Note the delay here! It may take some time for your relay chain to enter a new epoch.

Rococo & Westend Relay Chain Testnets

Is this Cumulus Parachain Template Rococo & Westend testnets compatible? Yes!

• Rococo is the testnet of Kusama (join the Rococo Faucet to get testing funds).
• Westend is the testnet of Polkadot (join the Westend Faucet to get testing funds).

See the Cumulus Workshop for the latest instructions to register a parathread/parachain on a relay chain.

NOTE: When running the relay chain and parachain, you must use the same tagged version of Polkadot and Cumulus so the collator would register successfully to the relay chain. You should test locally registering your parachain successfully before attempting to connect to any running relay chain network!

Find chainspec files to connect to live networks here. You want to be sure to use the correct git release tag in these files, as they change from time to time and must match the live network!

These networks are under constant development - so please follow the progress and update of your parachains in lock step with the testnet changes if you wish to connect to the network. Do join the Parachain Technical matrix chat room to ask questions and connect with the parachain building teams.

Learn More

• More detailed instructions to use Cumulus parachains are found in the Cumulus Workshop.
• Refer to the upstream Substrate Node Template to learn more about the structure of this project, the capabilities it encapsulates and the way in which those capabilities are implemented.
• Learn more about how a parachain block is added to a finalized chain here.