[libvirt] [PATCH 2/3] Improve error reporting with LXC controller

[Chen Hanxiao]

This would be far more convenient than checking logs.

Reviewed-by: Chen Hanxiao <chenhanxiao at cn.fujitsu.com>

> -----Original Message-----
> From: libvir-list-bounces at redhat.com
[mailto:libvir-list-bounces at redhat.com]
> On Behalf Of Daniel P. Berrange
> Sent: Saturday, October 12, 2013 12:54 AM
> To: libvir-list at redhat.com
> Subject: [libvirt] [PATCH 2/3] Improve error reporting with LXC controller
> 
> From: "Daniel P. Berrange" <berrange at redhat.com>
> 
> The LXC code would read the log file if an LXC guest failed to
> startup. There were a number of failure cases where the guest
> will not start and libvirtd never gets as far as looking at the
> log file.
> 
> Fix this by replacing some earlier generic errors with messages
> from the log.
> 
> Signed-off-by: Daniel P. Berrange <berrange at redhat.com>
> ---
>  src/lxc/lxc_process.c | 31 +++++++++++++++++++++++++------
>  1 file changed, 25 insertions(+), 6 deletions(-)
> 
> diff --git a/src/lxc/lxc_process.c b/src/lxc/lxc_process.c
> index d07ff13..840e138 100644
> --- a/src/lxc/lxc_process.c
> +++ b/src/lxc/lxc_process.c
> @@ -980,6 +980,7 @@ int virLXCProcessStart(virConnectPtr conn,
>      virErrorPtr err = NULL;
>      virLXCDriverConfigPtr cfg = virLXCDriverGetConfig(driver);
>      virCgroupPtr selfcgroup;
> +    int status;
> 
>      if (virCgroupNewSelf(&selfcgroup) < 0)
>          return -1;
> @@ -1182,9 +1183,18 @@ int virLXCProcessStart(virConnectPtr conn,
>          VIR_WARN("Unable to seek to end of logfile: %s",
>                   virStrerror(errno, ebuf, sizeof(ebuf)));
> 
> -    if (virCommandRun(cmd, NULL) < 0)
> +    if (virCommandRun(cmd, &status) < 0)
>          goto cleanup;
> 
> +    if (status != 0) {
> +        if (virLXCProcessReadLogOutput(vm, logfile, pos, ebuf,
sizeof(ebuf))
> <= 0)
> +            snprintf(ebuf, sizeof(ebuf), "unexpected exit status %d",
> status);
> +        virReportError(VIR_ERR_INTERNAL_ERROR,
> +                       _("guest failed to start: %s"), ebuf);
> +        goto cleanup;
> +    }
> +
> +
>      if (VIR_CLOSE(handshakefds[1]) < 0) {
>          virReportSystemError(errno, "%s", _("could not close handshake
> fd"));
>          goto cleanup;
> @@ -1193,16 +1203,25 @@ int virLXCProcessStart(virConnectPtr conn,
>      /* Connect to the controller as a client *first* because
>       * this will block until the child has written their
>       * pid file out to disk & created their cgroup */
> -    if (!(priv->monitor = virLXCProcessConnectMonitor(driver, vm)))
> +    if (!(priv->monitor = virLXCProcessConnectMonitor(driver, vm))) {
> +        VIR_ERROR("Here");
> +        /* Intentionally overwrite the real monitor error message,
> +         * since a better one is almost always found in the logs
> +         */
> +        if (virLXCProcessReadLogOutput(vm, logfile, pos, ebuf,
sizeof(ebuf)) >
> 0) {
> +        VIR_ERROR("tHere");
> +            virResetLastError();
> +            virReportError(VIR_ERR_INTERNAL_ERROR,
> +                           _("guest failed to start: %s"), ebuf);
> +        }
>          goto cleanup;
> +    }
> 
>      /* And get its pid */
>      if ((r = virPidFileRead(cfg->stateDir, vm->def->name, &vm->pid)) < 0)
{
> -        char out[1024];
> -
> -        if (virLXCProcessReadLogOutput(vm, logfile, pos, out, 1024) > 0)
> +        if (virLXCProcessReadLogOutput(vm, logfile, pos, ebuf,
sizeof(ebuf)) >
> 0)
>              virReportError(VIR_ERR_INTERNAL_ERROR,
> -                           _("guest failed to start: %s"), out);
> +                           _("guest failed to start: %s"), ebuf);
>          else
>              virReportSystemError(-r,
>                                   _("Failed to read pid file %s/%s.pid"),
> --
> 1.8.3.1
> 
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