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Every time when I start my parachain, I see Alice, Bob, Charlie, Dave,... etc and each of them has 1.1529 MUNIT on Polkadot.js.org's Accounts -> Accounts -> My Account page.

How does Polkadot.js.org get those initial account balances?

I found this code in chain_spec.rs in substrate-parachain-template repository https://github.com/substrate-developer-hub/substrate-parachain-template/blob/main/node/src/chain_spec.rs#L119 :

pub fn development_config() -> ChainSpec {
    // the same code as in local_testnet_config() below, except:
    // Name: "Development",
    // ID  : "dev",
    // ChainType::Development
    // Protocol ID and Properties: None,
}
pub fn local_testnet_config() -> ChainSpec {
    // Give your base currency a unit name and decimal places
    let mut properties = sc_chain_spec::Properties::new();
    properties.insert("tokenSymbol".into(), "UNIT".into());
    properties.insert("tokenDecimals".into(), 12.into());
    properties.insert("ss58Format".into(), 42.into());

    ChainSpec::from_genesis(
        // Name
        "Local Testnet",
        // ID
        "local_testnet",
        ChainType::Local,
        move || {
            testnet_genesis(
                // initial collators.
                vec![
                    (
                        get_account_id_from_seed::<sr25519::Public>("Alice"),
                        get_collator_keys_from_seed("Alice"),
                    ),
                    (
                        get_account_id_from_seed::<sr25519::Public>("Bob"),
                        get_collator_keys_from_seed("Bob"),
                    ),
                ],
                vec![
                    get_account_id_from_seed::<sr25519::Public>("Alice"),
                    get_account_id_from_seed::<sr25519::Public>("Bob"),
                    get_account_id_from_seed::<sr25519::Public>("Charlie"),
                    get_account_id_from_seed::<sr25519::Public>("Dave"),
                    get_account_id_from_seed::<sr25519::Public>("Eve"),
                    get_account_id_from_seed::<sr25519::Public>("Ferdie"),
                    get_account_id_from_seed::<sr25519::Public>("Alice//stash"),
                    get_account_id_from_seed::<sr25519::Public>("Bob//stash"),
                    get_account_id_from_seed::<sr25519::Public>("Charlie//stash"),
                    get_account_id_from_seed::<sr25519::Public>("Dave//stash"),
                    get_account_id_from_seed::<sr25519::Public>("Eve//stash"),
                    get_account_id_from_seed::<sr25519::Public>("Ferdie//stash"),
                ],
                1000.into(),
            )
        },
        // Bootnodes
        Vec::new(),
        // Telemetry
        None,
        // Protocol ID
        Some("template-local"),
        // Fork ID
        None,
        // Properties
        Some(properties),
        // Extensions
        Extensions {
            relay_chain: "rococo-local".into(), // You MUST set this to the correct network!
            para_id: 1000,
        },
    )
}

fn testnet_genesis(
    invulnerables: Vec<(AccountId, AuraId)>,
    endowed_accounts: Vec<AccountId>,
    root_key: AccountId,
    id: ParaId,
) -> GenesisConfig {
        system: SystemConfig { ... },
        balances: hero_runtime::BalancesConfig {
            balances: endowed_accounts.iter().cloned().map(|k| (k, 1 << 60)).collect(),
        },
        parachain_info: hero_runtime::ParachainInfoConfig { parachain_id: id },
        ...
}

I see this balances: endowed_accounts.iter().cloned().map(|k| (k, 1 << 60)).collect(), maps ALICE, BOB, etc.. to 1 << 60, which uses Rust's left shift operator to make ( A << B ) equivalent to A*2^B

for example:

1000 << 2 returns 1000*(2^2) = 4000

1 << 60 returns 1*(2^60) = 1.152921505×10^18, which matches what I saw in Polkadot.js.org

But both development_config() or local_testnet_config() use this testnet_genesis() to generate initial account balances.

When I ran my local parachain with a local relay chain as described in "Connect other chains" https://docs.substrate.io/tutorials/connect-other-chains/, was I running it through development_config() or local_testnet_config() ?

Both those two config functions use testnet_genesis()

fn testnet_genesis(
  invulnerables: Vec<(AccountId, AuraId)>,
  endowed_accounts: Vec<AccountId>,
  root_key: AccountId,
  id: ParaId,
){ ... }

What determines this testnet_genesis() id argument to be 1000.into(), or 2000.into(),?

When running my parachain locally with relay chain, I need to reserve paraId 2000 as described in the above "Connect other chains" tutorial.

Does this paraId 2000 determine the testnet_genesis() id argument to be 2000.into()?

2 Answers 2

3

Was I running it through development_config() or local_testnet_config() ?

By default, you are running it through local_testnet_config. This default configuration can be found in node/src/command.rs in the load_spec function. See here:

fn load_spec(id: &str) -> std::result::Result<Box<dyn ChainSpec>, String> {
    Ok(match id {
        "dev" => Box::new(chain_spec::development_config()),
        "template-rococo" => Box::new(chain_spec::local_testnet_config()),
        "" | "local" => Box::new(chain_spec::local_testnet_config()),
        path => Box::new(chain_spec::ChainSpec::from_json_file(std::path::PathBuf::from(path))?),
    })
}

The last match arm "" | "local" is the one that runs by default (empty string). If you wanted to change which chain-spec is used (e.g. "dev"), simply provide --chain "dev" to your run command. To go one step further, play around with the build-spec command and compare the outputted files.

#generate dev spec (uses development_config)
./target/release/<node-executable> build-spec --chain dev > dev-spec.json

#generate local spec (uses local_testnet_config)
./target/release/<node-executable> build-spec --chain local > local-spec.json

Furthermore, you are correct in noting that both development_config and local_testnet_config use testnet_genesis. So, either way (in this case) the balances will come from testnet_genesis. However, you could easily modify this file to have, for example, a testnet_genesis and dev_genesis that use different balances. You could also alter which accounts have initial balances in local_testnet_config or development_config.

What determines this testnet_genesis() id argument to be 1000.into(), or 2000.into(),?

As you noted, the paraID you register on the relay chain must be placed into the id field in the chain spec.

2
  • but in substrate-parachain-template's chain_spec.rs, why is id 1000 for both development_config() and local_testnet_config() while the tutorial "Connect other chains" can use paraId 2000 ?
    – Russo
    Sep 7, 2022 at 16:46
  • @Russo I am not sure why the default is 1000 in the template's chain_spec. The 2000, however, is used because the relay-chain has reserved < 2000 IDs for system level & common good chains. So, the first ID available to reserve will be 2000. Sep 7, 2022 at 16:58
1

If you're using the substrate contracts node then the balances are coming from the chain_spec.rs file.

        balances: BalancesConfig {
            // Configure endowed accounts with initial balance of 1 << 60.
            balances: endowed_accounts.iter().cloned().map(|k| (k, 1 << 60)).collect(),
        },

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