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fix(wassette): send log to stderr for stdio transport #86

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Merged
asw101 merged 2 commits into from
Aug 5, 2025
Merged

fix(wassette): send log to stderr for stdio transport #86

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d7d0aa0
fix(wassette): send log to stderr for stdio transport
Mossaka Aug 5, 2025
a056f87
Disable ANSI escape codes
asw101 Aug 5, 2025
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99 changes: 51 additions & 48 deletions src/main.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -180,18 +180,6 @@ Key points:

#[tokio::main]
async fn main() -> Result<()> {
tracing_subscriber::registry()
.with(
tracing_subscriber::EnvFilter::try_from_default_env()
.unwrap_or_else(|_| {
"info,cranelift_codegen=warn,cranelift_entity=warn,cranelift_bforest=warn,cranelift_frontend=warn"
.to_string()
.into()
}),
)
.with(tracing_subscriber::fmt::layer())
.init();

let cli = Cli::parse();

match &cli.command {
Expand All @@ -200,49 +188,64 @@ async fn main() -> Result<()> {
stdio,
http,
} => {
// Initialize logging based on transport type
let use_stdio_transport = match (*stdio, *http) {
(false, false) => true, // Default case: use stdio transport
(true, false) => true, // Stdio transport only
(false, true) => false, // HTTP transport only
(true, true) => {
return Err(anyhow::anyhow!(
"Running both stdio and HTTP transports simultaneously is not supported. Please choose one."
));
}
};

// Configure logging - use stderr for stdio transport to avoid interfering with MCP protocol
let env_filter = tracing_subscriber::EnvFilter::try_from_default_env()
.unwrap_or_else(|_| {
"info,cranelift_codegen=warn,cranelift_entity=warn,cranelift_bforest=warn,cranelift_frontend=warn"
.to_string()
.into()
});
Comment on lines +204 to +209
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@asw101 asw101 Aug 5, 2025

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Suggested change
let env_filter = tracing_subscriber::EnvFilter::try_from_default_env()
.unwrap_or_else(|_| {
"info,cranelift_codegen=warn,cranelift_entity=warn,cranelift_bforest=warn,cranelift_frontend=warn"
.to_string()
.into()
});
let env_filter =
tracing_subscriber::EnvFilter::try_from_default_env().unwrap_or_else(|_| {
if env::var("RUST_LOG").is_ok() {
"info,cranelift_codegen=warn,cranelift_entity=warn,cranelift_bforest=warn,cranelift_frontend=warn"
.to_string()
.into()
} else {
"warn,cranelift_codegen=warn,cranelift_entity=warn,cranelift_bforest=warn,cranelift_frontend=warn"
.to_string()
.into()
}
});

I've disabled ANSII escape codes but added this optional tweak. If RUST_LOG is set, we change the level from warn to info to get the logging depth we had before.

This is because VS Code will still output the following [warning] for any output on stderr.

2025-08-05 15:46:04.454 [warning] [server stderr] 2025-08-05T19:46:04.452371Z  INFO handle_tools_list:get_component_tools: mcp_server::components: Total tools collected: 0

However, it is not trying to parse it, so I think it's OK to merge and leave as-is for now.

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@asw101 asw101 Aug 5, 2025

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Will merge in the meantime.


let registry = tracing_subscriber::registry().with(env_filter);

if use_stdio_transport {
registry
.with(
tracing_subscriber::fmt::layer()
.with_writer(std::io::stderr)
.with_ansi(false),
)
.init();
} else {
registry.with(tracing_subscriber::fmt::layer()).init();
}

let components_dir = PathBuf::from(plugin_dir);

let lifecycle_manager = LifecycleManager::new(&components_dir).await?;

let server = McpServer::new(lifecycle_manager);

match (*stdio, *http) {
(false, false) => {
// Default case: use stdio transport
tracing::info!("Starting MCP server with stdio transport (default)");
let transport = stdio_transport();
let running_service = serve_server(server, transport).await?;
if use_stdio_transport {
tracing::info!("Starting MCP server with stdio transport");
let transport = stdio_transport();
let running_service = serve_server(server, transport).await?;

tokio::signal::ctrl_c().await?;
let _ = running_service.cancel().await;
}
(true, false) => {
// Stdio transport only
tracing::info!("Starting MCP server with stdio transport");
let transport = stdio_transport();
let running_service = serve_server(server, transport).await?;

tokio::signal::ctrl_c().await?;
let _ = running_service.cancel().await;
}
(false, true) => {
// HTTP transport only
tracing::info!(
"Starting MCP server on {} with HTTP transport",
BIND_ADDRESS
);
let ct = SseServer::serve(BIND_ADDRESS.parse().unwrap())
.await?
.with_service(move || server.clone());

tokio::signal::ctrl_c().await?;
ct.cancel();
}
(true, true) => {
return Err(anyhow::anyhow!(
"Running both stdio and HTTP transports simultaneously is not supported. Please choose one."
));
}
tokio::signal::ctrl_c().await?;
let _ = running_service.cancel().await;
} else {
tracing::info!(
"Starting MCP server on {} with HTTP transport",
BIND_ADDRESS
);
let ct = SseServer::serve(BIND_ADDRESS.parse().unwrap())
.await?
.with_service(move || server.clone());

tokio::signal::ctrl_c().await?;
ct.cancel();
}

tracing::info!("MCP server shutting down");
Expand Down