[lxc-devel] [PATCH v2] Create log file in lxcpath for non-system containers

[Serge Hallyn]

Quoting Dwight Engen (dwight.engen at oracle.com):
> +/*
> + * Build the path to the log file
> + * @name     : the name of the container
> + * @lxcpath  : the lxcpath to use as a basename or NULL to use LOGPATH
> + * Returns malloced path on sucess, or NULL on failure
> + */
> +static char *build_log_path(const char *name, const char *lxcpath)
>  {
>  	char *p;
>  	int len, ret;
>  
>  	/*
> -	 * '$logpath' + '/' + '$name' + '.log' + '\0'
> -	 * or
> +	 * If USE_CONFIGPATH_LOGS is true the resulting path will be:
>  	 * '$logpath' + '/' + '$name' + '/' + '$name' + '.log' + '\0'
> -	 * sizeof(LOGPATH) includes its \0
> +	 *
> +	 * If USE_CONFIGPATH_LOGS is false the resulting path will be:
> +	 * '$logpath' + '/' + '$name' + '.log' + '\0'
>  	 */
> -	len = sizeof(LOGPATH) + strlen(name) + 6;
> +	len = strlen(name) + 6; /* 6 == '/' + '.log' + '\0' */
> +	if (!lxcpath)
> +		lxcpath = LOGPATH;
>  #if USE_CONFIGPATH_LOGS
> -	len += strlen(name) + 1;  /* add "/$container_name/" */
> +	len += strlen(lxcpath) + 1 + strlen(name) + 1;  /* add "/$container_name/" */
> +#else
> +	len += strlen(lxcpath) + 1;
>  #endif
>  	p = malloc(len);
>  	if (!p)
>  		return p;
>  #if USE_CONFIGPATH_LOGS
> -	ret = snprintf(p, len, "%s/%s/%s.log", LOGPATH, name, name);
> +	ret = snprintf(p, len, "%s/%s/%s.log", lxcpath, name, name);
>  #else
> -	ret = snprintf(p, len, "%s/%s.log", LOGPATH, name);
> +	ret = snprintf(p, len, "%s/%s.log", lxcpath, name);

Hi Dwight,

I've pushed this patch to staging, but I do notice an oddity when
USE_CONFIGPATH_LOGS=n (as on ubuntu).  When I now start a container
with an lxcpath, i.e. lxc-start -n c1 -P /home/serge/lxcbase,
then the logfile is at /home/serge/lxcbase/dir1.log, not
/home/serge/lxcbase/dir1/dir1.log.  I think it would be better to have
something like

 #if USE_CONFIGPATH_LOGS
	ret = snprintf(p, len, "%s/%s/%s.log", lxcpath, name, name);
 #else
	if (lxcpath == default_lxc_path())
		ret = snprintf(p, len, "%s/%s.log", lxcpath, name);
	else
		ret = snprintf(p, len, "%s/%s/%s.log", lxcpath, name, name);
 #endif

Well, that or we use $lxcpath/logs/$name.log, but I prefer to keep the
rule: we either use $LOGPATH/$name.log, or else
$lxcpath/$name/$name.log, always.

Thoughts?

thanks,
-serge