databendlabs/databend · error

Failed to create new_grpc_client function

Error message

Failed to create new_grpc_client function: {}

What it means

setup_lua_environment registers a `new_grpc_client` Lua function that constructs a MetaGrpcClient. If mlua's create_function fails to wrap the Rust closure, this anyhow error is raised before the function is attached to the metactl table.

Solutions

1. Rebuild metactl with a consistent mlua version/feature set
2. Retry after resolving memory constraints
3. Upgrade to a release where mlua create_function issues are fixed
4. Check that no other component corrupted the shared Lua state before setup

match run_lua_script(&script) {
    Err(e) if e.to_string().contains("Failed to create new_grpc_client") => {
        eprintln!("Lua function registration failed: {e}; rebuild/retry");
    }
    other => other?,
}

When it happens

Trigger: Lua environment setup failing at function creation — normally due to mlua state problems, memory pressure, or incompatible mlua/runtime versions in the build.

Common situations: Running metactl Lua scripts in builds where the mlua feature set or Lua runtime is broken; heavily constrained environments.

Related errors

• Failed to create metactl table
• Failed to create new_admin_client function
• Failed to register new_grpc_client
• Failed to register new_admin_client
• Failed to register NULL constant

AI-assisted analysis of databendlabs/databend@288d84d76e (2026-09-11). Data as JSON: /api/errors/e3252ea09d3f8bba. Report an issue: GitHub.

Appendix: source

Thrown at src/meta/control/src/lua_support.rs:404

        .map_err(|e| anyhow::anyhow!("Failed to create metactl table: {}", e))?;

    // Register new_grpc_client function
    let new_grpc_client = lua
        .create_function(move |_lua, address: String| {
            let client = MetaGrpcClient::try_create(
                vec![address],
                "root",
                "xxx",
                Some(Duration::from_secs(2)),
                Some(Duration::from_secs(1)),
                None,
                DEFAULT_GRPC_MESSAGE_SIZE,
            )
            .map_err(|e| mlua::Error::external(format!("Failed to create gRPC client: {}", e)))?;

            Ok(LuaGrpcClient::new(client))
        })
        .map_err(|e| anyhow::anyhow!("Failed to create new_grpc_client function: {}", e))?;

    metactl_table
        .set("new_grpc_client", new_grpc_client)
        .map_err(|e| anyhow::anyhow!("Failed to register new_grpc_client: {}", e))?;

    // Register new_admin_client function
    let new_admin_client = lua
        .create_function(|_lua, address: String| {
            let client = MetaAdminClient::new(&address);
            Ok(LuaAdminClient::new(client))
        })
        .map_err(|e| anyhow::anyhow!("Failed to create new_admin_client function: {}", e))?;

    metactl_table
        .set("new_admin_client", new_admin_client)
        .map_err(|e| anyhow::anyhow!("Failed to register new_admin_client: {}", e))?;

    // Export NULL constant to metactl namespace

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