kola/qemuexec: add --console-to-file

We want kola to be in control of what happens to the serial console. But
`runvm` wants to redirect the console to a file.

Add a flag to `qemuexec` to make that possible.

Author: jlebon

mantle/cmd/kola/qemuexec.go

@@ -61,6 +61,8 @@ var (
 
 	devshell        bool
 	devshellConsole bool
+
+	consoleFile string
 )
 
 func init() {
@@ -81,6 +83,7 @@ func init() {
 	cmdQemuExec.Flags().StringArrayVar(&bindrw, "bind-rw", nil, "Same as above, but writable")
 	cmdQemuExec.Flags().BoolVarP(&forceConfigInjection, "inject-ignition", "", false, "Force injecting Ignition config using guestfs")
 	cmdQemuExec.Flags().BoolVar(&propagateInitramfsFailure, "propagate-initramfs-failure", false, "Error out if the system fails in the initramfs")
+	cmdQemuExec.Flags().StringVarP(&consoleFile, "console-to-file", "", "", "Filepath in which to save serial console logs")
 
 }
 
@@ -114,6 +117,10 @@ func runQemuExec(cmd *cobra.Command, args []string) error {
 
 	if devshellConsole {
 		devshell = true
+
+		if consoleFile != "" {
+			return fmt.Errorf("Cannot use console devshell and --console-to-file")
+		}
 	}
 	if devshell {
 		if directIgnition {
@@ -244,6 +251,7 @@ func runQemuExec(cmd *cobra.Command, args []string) error {
 		builder.EnableUsermodeNetworking(h)
 	}
 	builder.InheritConsole = true
+	builder.ConsoleFile = consoleFile
 	builder.Append(args...)
 
 	if devshell && !devshellConsole {

src/cmdlib.sh

@@ -500,7 +500,8 @@ EOF
     echo "$@" > "${tmp_builddir}"/cmd.sh
 
     touch "${runvm_console}"
-    kola_args=(kola qemuexec -m 2048 --auto-cpus -U --workdir none)
+    kola_args=(kola qemuexec -m 2048 --auto-cpus -U --workdir none \
+               --console-to-file "${runvm_console}")
     base_qemu_args=(-drive 'if=none,id=root,format=raw,snapshot=on,file='"${vmbuilddir}"'/root,index=1' \
                     -device 'virtio-blk,drive=root'
                     -kernel "${vmbuilddir}/kernel" -initrd "${vmbuilddir}/initrd" \
@@ -518,7 +519,6 @@ EOF
 
     if [ -z "${RUNVM_SHELL:-}" ]; then
         if ! "${kola_args[@]}" -- "${base_qemu_args[@]}" \
-            -serial file:"${runvm_console}" \
             -device virtserialport,chardev=virtioserial0,name=cosa-cmdout \
             -chardev stdio,id=virtioserial0 \
             "${qemu_args[@]}" <&-; then # the <&- here closes stdin otherwise qemu waits forever