{"record":{"id":"da1b65f4edafa650","repo":"loco-rs/loco","slug":"failed-to-get-local-address","errorCode":null,"errorMessage":"Failed to get local address","messagePattern":"Failed to get local address","errorType":"panic","errorClass":null,"httpStatus":null,"severity":"error","filePath":"src/testing/request.rs","lineNumber":162,"sourceCode":"pub fn get_base_url_port(port: i32) -> String {\n    format!(\"http://{TEST_BINDING_SERVER}:{port}/\")\n}\n\n/// Returns a unique port number. Usually increments by 1 starting from 59126\n///\n/// # Panics\n///\n/// Will panic if binding to test server address fails or if getting the local address fails\npub async fn get_available_port() -> i32 {\n    let addr = format!(\"{TEST_BINDING_SERVER}:0\");\n    let listener = TcpListener::bind(addr)\n        .await\n        .expect(\"Failed to bind to address\");\n\n    i32::from(\n        listener\n            .local_addr()\n            .expect(\"Failed to get local address\")\n            .port(),\n    )\n}\n\n/// Bootstraps test application with test environment hard coded.\n///\n/// # Example\n///\n/// The provided example demonstrates how to boot the test case with the\n/// application context.\n///\n/// ```rust,ignore\n/// use myapp::app::App;\n/// use loco_rs::testing::prelude::*;\n///\n/// #[tokio::test]\n/// async fn test_create_user() {\n///     let boot = boot_test::<App>().await;","sourceCodeStart":144,"sourceCodeEnd":180,"githubUrl":"https://github.com/loco-rs/loco/blob/23639d1e360dbc618073642b507d6f8664adbaff/src/testing/request.rs#L144-L180","documentation":"After binding, get_available_port calls listener.local_addr() to discover the OS-assigned port and .expect()s the result. If the local address cannot be retrieved the panic message is 'Failed to get local address'. This is rare — it usually indicates the socket was already closed or an OS-level socket error occurred.","triggerScenarios":"Calling get_available_port() and having listener.local_addr() return Err: the listener was dropped/closed before the call, an OS socket error (fd exhaustion, EBADF), or an unusual network stack that cannot report the address.","commonSituations":"File-descriptor exhaustion under heavy parallel test load; custom network stacks (gVisor, some containers) with incomplete getsockname support; tokio runtime shutdown racing the helper; patched/virtualized loopback devices.","solutions":["Check ulimit -n / fd exhaustion if running many tests concurrently; raise the limit or reduce parallelism.","Retry get_available_port() — the failure is typically transient/environmental.","Verify the runtime environment supports getsockname on loopback sockets (gVisor/sandbox configs).","Update the runtime/tokio and OS packages; check for known socket bugs in the container runtime."],"exampleFix":null,"handlingStrategy":"retry","validationCode":"// precheck fd headroom\nlet free: i64 = std::fs::read_to_string(\"/proc/sys/fs/file-nr\")\n    .ok()\n    .and_then(|s| s.split_whitespace().next().and_then(|n| n.parse().ok()))\n    .unwrap_or(0);\nassert!(free < 1_000_000, \"file descriptors near exhaustion\");","typeGuard":null,"tryCatchPattern":"let port = (0..3).find_map(|_| get_available_port_safe()).unwrap_or_else(|| {\n    panic!(\"could not obtain a local port after retries\")\n});","preventionTips":["Raise ulimit -n in CI when running large parallel test suites","Retry port acquisition on transient socket errors","Keep the listener alive until after local_addr() is read","Test container/network-stack compatibility (gVisor etc.) once in CI setup"],"tags":["rust","testing","network","socket"],"backgroundTag":"connection-refused","analyzedSha":"23639d1e360dbc618073642b507d6f8664adbaff","analyzedAt":"2026-09-12T01:47:20.769Z","contentChangedAt":"2026-09-12T01:47:20.769Z","schemaVersion":2},"datasetVersion":"2026-09-16T04:17:20.429Z"}