Add channel message when exec fails

Signed-off-by: Yashodhan Joshi <yjdoc2@gmail.com>

crates/libcontainer/src/process/channel.rs

@@ -173,6 +173,10 @@ impl MainReceiver {
             })?;
         match msg {
             Message::InitReady => Ok(()),
+            // this case in unique and known enough to have a special error format
+            Message::ExecFailed(err) => Err(ChannelError::ExecError(format!(
+                "error in executing process : {err}"
+            ))),
             msg => Err(ChannelError::UnexpectedMessage {
                 expected: Message::InitReady,
                 received: msg,

crates/libcontainer/src/process/container_init_process.rs

@@ -355,6 +355,12 @@ pub fn container_init_process(
             })?;
         }
 
+        // As we have chagned the root mount, from here on
+        // logs are no longer visible in journalctl
+        // so make sure that you bubble up any errors
+        // and do not call unwrap as any panics would not be correctly logged
+
+
         rootfs.adjust_root_mount_propagation(linux).map_err(|err| {
             tracing::error!(?err, "failed to adjust root mount propagation");
             InitProcessError::RootFS(err)

crates/libcontainer/src/process/container_intermediate_process.rs

@@ -122,19 +122,19 @@ pub fn container_intermediate_process(
             match container_init_process(&args, &mut main_sender, &mut init_receiver) {
                 Ok(_) => 0,
                 Err(e) => {
+                    tracing::error!("failed to initialize container process: {e}");
+                    if let Err(err) = main_sender.exec_failed(e.to_string()) {
+                        tracing::error!(?err, "failed sending error to main sender");
+                    }
                     if let ContainerType::TenantContainer { exec_notify_fd } = args.container_type {
                         let buf = format!("{e}");
                         if let Err(err) = write(exec_notify_fd, buf.as_bytes()) {
                             tracing::error!(?err, "failed to write to exec notify fd");
-                            return -1;
                         }
                         if let Err(err) = close(exec_notify_fd) {
                             tracing::error!(?err, "failed to close exec notify fd");
-                            return -1;
                         }
                     }
-
-                    tracing::error!("failed to initialize container process: {e}");
                     -1
                 }
             }

crates/libcontainer/src/workload/default.rs

@@ -34,7 +34,13 @@ impl Executor for DefaultExecutor {
             .collect();
         unistd::execvp(&cstring_path, &a).map_err(|err| {
             tracing::error!(?err, filename = ?cstring_path, args = ?a, "failed to execvp");
-            ExecutorError::Execution(err.into())
+            ExecutorError::Execution(
+                format!(
+                    "error '{}' executing '{:?}' with args '{:?}'",
+                    err, cstring_path, a
+                )
+                .into(),
+            )
         })?;
 
         // After execvp is called, the process is replaced with the container
@@ -46,14 +52,18 @@ impl Executor for DefaultExecutor {
         let proc = spec
             .process()
             .as_ref()
-            .ok_or(ExecutorValidationError::InvalidArg)?;
+            .ok_or(ExecutorValidationError::ArgValidationError(
+                "spec did not contain process".into(),
+            ))?;
 
         if let Some(args) = proc.args() {
             let envs: Vec<String> = proc.env().as_ref().unwrap_or(&vec![]).clone();
             let path_vars: Vec<&String> = envs.iter().filter(|&e| e.starts_with("PATH=")).collect();
             if path_vars.is_empty() {
                 tracing::error!("PATH environment variable is not set");
-                Err(ExecutorValidationError::InvalidArg)?;
+                Err(ExecutorValidationError::ArgValidationError(
+                    "PATH environment variable is not set".into(),
+                ))?;
             }
             let path_var = path_vars[0].trim_start_matches("PATH=");
             match get_executable_path(&args[0], path_var) {
@@ -62,7 +72,10 @@ impl Executor for DefaultExecutor {
                         executable = ?args[0],
                         "executable for container process not found in PATH",
                     );
-                    Err(ExecutorValidationError::InvalidArg)?;
+                    Err(ExecutorValidationError::ArgValidationError(format!(
+                        "executable '{}' not found in $PATH",
+                        args[0]
+                    )))?;
                 }
                 Some(path) => match is_executable(&path) {
                     Ok(true) => {
@@ -73,7 +86,10 @@ impl Executor for DefaultExecutor {
                             executable = ?path,
                             "executable does not have the correct permission set",
                         );
-                        Err(ExecutorValidationError::InvalidArg)?;
+                        Err(ExecutorValidationError::ArgValidationError(format!(
+                            "executable '{}' at path '{:?}' does not have correct permissions",
+                            args[0], path
+                        )))?;
                     }
                     Err(err) => {
                         tracing::error!(
@@ -81,7 +97,10 @@ impl Executor for DefaultExecutor {
                             ?err,
                             "failed to check permissions for executable",
                         );
-                        Err(ExecutorValidationError::InvalidArg)?;
+                        Err(ExecutorValidationError::ArgValidationError(format!(
+                            "failed to check permissions for executable '{}' at path '{:?}' : {}",
+                            args[0], path, err
+                        )))?;
                     }
                 },
             }

crates/libcontainer/src/workload/mod.rs

@@ -20,8 +20,8 @@ pub enum ExecutorError {
 pub enum ExecutorValidationError {
     #[error("{0} executor can't handle spec")]
     CantHandle(&'static str),
-    #[error("invalid argument")]
-    InvalidArg,
+    #[error("{0}")]
+    ArgValidationError(String),
 }
 
 // Here is an explanation about the complexity below regarding to

crates/youki/src/main.rs

@@ -123,6 +123,7 @@ fn main() -> Result<()> {
             CommonCmd::Exec(exec) => match commands::exec::exec(exec, root_path) {
                 Ok(exit_code) => std::process::exit(exit_code),
                 Err(e) => {
+                    tracing::error!("error in executing command: {:?}", e);
                     eprintln!("exec failed : {e}");
                     std::process::exit(-1);
                 }
@@ -135,6 +136,7 @@ fn main() -> Result<()> {
             CommonCmd::Run(run) => match commands::run::run(run, root_path, systemd_cgroup) {
                 Ok(exit_code) => std::process::exit(exit_code),
                 Err(e) => {
+                    tracing::error!("error in executing command: {:?}", e);
                     eprintln!("run failed : {e}");
                     std::process::exit(-1);
                 }
@@ -151,6 +153,7 @@ fn main() -> Result<()> {
 
     if let Err(ref e) = cmd_result {
         tracing::error!("error in executing command: {:?}", e);
+        eprintln!("error in executing command: {:?}", e);
     }
     cmd_result
 }