fix: Support creating file with open_file_nonblock

Updates the `OpenOptions` with `.create(true)` to support creating a
file when if it doesn't exist. This also brings the functionality
inline with the documentation which notes
`Create and opens a File for writing to it.`. This improves usability
simplifying setting up the logger.

Signed-off-by: Jonathan Woollett-Light <[email protected]>

Author: Jonathan Woollett-Light

docs/getting-started.md

@@ -134,9 +134,6 @@ sudo iptables -I FORWARD 1 -i tap0 -o eth0 -j ACCEPT
 API_SOCKET="/tmp/firecracker.socket"
 LOGFILE="./firecracker.log"
 
-# Create log file
-touch $LOGFILE
-
 # Set log file
 curl -X PUT --unix-socket "${API_SOCKET}" \
     --data "{

src/vmm/src/vmm_config/logger.rs

@@ -152,15 +152,6 @@ mod tests {
     fn test_init_logger() {
         let default_instance_info = InstanceInfo::default();
 
-        // Error case: initializing logger with invalid pipe returns error.
-        let desc = LoggerConfig {
-            log_path: PathBuf::from("not_found_file_log"),
-            level: LoggerLevel::Debug,
-            show_level: false,
-            show_log_origin: false,
-        };
-        assert!(init_logger(desc, &default_instance_info).is_err());
-
         // Initializing logger with valid pipe is ok.
         let log_file = TempFile::new().unwrap();
         let desc = LoggerConfig {

src/vmm/src/vmm_config/metrics.rs

@@ -43,12 +43,6 @@ mod tests {
 
     #[test]
     fn test_init_metrics() {
-        // Error case: initializing metrics with invalid pipe returns error.
-        let desc = MetricsConfig {
-            metrics_path: PathBuf::from("not_found_file_metrics"),
-        };
-        assert!(init_metrics(desc).is_err());
-
         // Initializing metrics with valid pipe is ok.
         let metrics_file = TempFile::new().unwrap();
         let desc = MetricsConfig {

src/vmm/src/vmm_config/mod.rs

@@ -172,6 +172,7 @@ impl RateLimiterConfig {
 fn open_file_nonblock(path: &Path) -> Result<File, std::io::Error> {
     OpenOptions::new()
         .custom_flags(O_NONBLOCK)
+        .create(true)
         .read(true)
         .write(true)
         .open(path)

tests/integration_tests/functional/test_logging.py

@@ -112,26 +112,6 @@ def test_error_logs(test_microvm_with_api):
     _test_log_config(microvm=test_microvm_with_api, log_level="Error")
 
 
-def test_log_config_failure(test_microvm_with_api):
-    """
-    Check passing invalid FIFOs is detected and reported as an error.
-    """
-    microvm = test_microvm_with_api
-    microvm.spawn(create_logger=False)
-    microvm.basic_config()
-
-    response = microvm.logger.put(
-        log_path="invalid log fifo",
-        level="Info",
-        show_level=True,
-        show_log_origin=True,
-    )
-    # only works if log level is Debug
-    microvm.time_api_requests = False
-    assert microvm.api_session.is_status_bad_request(response.status_code)
-    assert response.json()["fault_message"]
-
-
 def test_api_requests_logs(test_microvm_with_api):
     """
     Test that API requests are logged.