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feat(devnet): add loopback_only flag for LAN testnet support #84

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feat(devnet): add loopback_only flag for LAN testnet support #84

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65d11e6
feat(devnet): add loopback_only flag for LAN devnet support
Nic-dorman Apr 29, 2026
b651365
fix(devnet): drop broken intra-doc link in loopback_only docstring
Nic-dorman Apr 29, 2026
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32 changes: 29 additions & 3 deletions src/devnet.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -164,6 +164,23 @@ pub struct DevnetConfig {
/// When `Some`, nodes will use this network (e.g. Anvil testnet) for
/// on-chain verification. Defaults to Arbitrum One when `None`.
pub evm_network: Option<EvmNetwork>,

/// Bind nodes to loopback addresses (`127.0.0.1`/`::1`) only.
///
/// When `true` (the default), nodes listen on loopback only — the
/// historical single-host devnet behavior, suitable for development
/// and integration tests where every node and every client run on
/// the same machine.
///
/// When `false`, nodes bind to all interfaces (`0.0.0.0`/`::`), which
/// is required for cross-host LAN devnets where client machines need
/// to reach the devnet's nodes via the lab server's LAN IP. The
/// transport-layer `allow_loopback` flag is enabled explicitly in this
/// mode so inter-node bootstrap (which still uses loopback addresses
/// on the lab host) continues to work.
///
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Copilot AI Apr 29, 2026

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The docs for loopback_only read a bit like setting it to false is sufficient for cross-host clients. In this module bootstrap_addrs() (and the ant-devnet manifest it produces) still always uses Ipv4Addr::LOCALHOST, so remote clients will need a rewritten/overridden bootstrap list even when nodes bind to 0.0.0.0/::. Consider adding an explicit note to avoid confusion about what this flag does/doesn’t change.

Suggested change
///
///
/// Note: this only affects the addresses nodes bind/listen on. It does
/// not rewrite bootstrap addresses produced by this module (including
/// [`Self::bootstrap_addrs()`] and the generated `ant-devnet` manifest),
/// which still use localhost addresses. Remote clients on other hosts
/// must therefore override or rewrite the bootstrap list to use a
/// reachable LAN/WAN IP for the devnet host.
///

Copilot uses AI. Check for mistakes.
/// Passed through to saorsa-core's `NodeConfigBuilder::local`.
pub loopback_only: bool,
}

impl Default for DevnetConfig {
Expand All @@ -185,6 +202,7 @@ impl Default for DevnetConfig {
enable_node_logging: false,
cleanup_data_dir: true,
evm_network: None,
loopback_only: true,
}
}
}
Expand Down Expand Up @@ -574,9 +592,17 @@ impl Devnet {
debug!("Starting node {} on port {}", node.index, node.port);
*node.state.write().await = NodeState::Starting;

let mut core_config = CoreNodeConfig::builder()
.port(node.port)
.local(true)
let builder = CoreNodeConfig::builder().port(node.port);
// Historical single-host devnet path uses local(true), which auto-enables
// allow_loopback for routing. LAN devnet path binds all interfaces and
// re-enables allow_loopback explicitly so inter-node bootstrap via
// loopback addresses continues to work.
let builder = if self.config.loopback_only {
builder.local(true)
} else {
builder.local(false).allow_loopback(true)
};
let mut core_config = builder
.max_message_size(crate::ant_protocol::MAX_WIRE_MESSAGE_SIZE)
.build()
.map_err(|e| DevnetError::Core(format!("Failed to create core config: {e}")))?;
Expand Down
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