Create log file in lxcpath for non-system containers

On Fri, 26 Apr 2013 10:18:12 -0500
Serge Hallyn <serge.hallyn@ubuntu.com> wrote:

> Quoting Dwight Engen (dwight.engen@oracle.com):
> > On Fri, 26 Apr 2013 09:37:49 -0500
> > Serge Hallyn <serge.hallyn@ubuntu.com> wrote:
> >
> > > Quoting Dwight Engen (dwight.engen@oracle.com):
> > > > Using lxc configured with --enable-configpath-log, and
> > > > specifying a path to the lxc commands with -P, the log file
> > > > path is generated with a basename of LOGPATH instead of the
> > > > lxcpath. This means for example if you do
> > > >
> > > > lxc-start -P /tmp/containers -n test01 -l INFO
> > > >
> > > > your log file will be
> > > >
> > > > /var/lib/lxc/test01/test01.log
> > > >
> > > > I was expecting the log to be /tmp/containers/test01/test01.log.
> > > > This is particularly confusing if you also have test01 on the
> > > > regular lxcpath. The patch below changes the log file path to be
> > > > based on lxcpath rather than LOGPATH when lxc is configured with
> > > > --enable-configpath-log.
> > > >
> > > > I think that even in the normal non --enable-configpath-log case
> > > > we should consider using lxcpath as the base and not having
> > > > LOGPATH at all, as attempting to create the log files
> > > > in /var/log is not going to work for regular users on their own
> > > > lxcpath. If we want that, I'll update the patch to do that as
> > > > well.
> > >
> > >
> > > Perhaps we should do:
> > >
> > > 	1. If lxcpath == default_lxc_path(), then first choice is
> > > 	   LOGPATH, second is lxcpath/container.log
> > > 	2. when opening, if first choice fails, use second choice
> > > 	   if there is any.
> > >
> > > That way 'system' containers will go to /var/log/lxc, as I think
> > > they should.  Custom-lxcpath containers should never go
> > > to /var/log/lxc, since their names could be dups of containers in
> > > default_lxc_path(). And if the system is a weird one where
> > > default_lxc_path is set up so that an unprivileged user can use
> > > it, then we should log into $lxcpath.
> >
> > That sounds good to me. So these rules would apply in both the
> > regular and --enable-configpath-log cases.

I updated the patch to try to open the log file according to the
choices given above. Along the way I cleaned up log.c a bit, making
some things static, grouping external interfaces together, etc...
Hopefully that doesn't add too much noise.

> > > (Note this patch will trivially conflict with my new lxc_clone.c
> > > causing it to fail to build - unfortunate result of timing)
> >
> > Yeah unfortunately this touches every lxc_log_init() caller. I can
> > work on the above logic and re-submit after your new lxc_clone
> > stuff goes in.
>
> No no, I'll just need to remember to update mine.  Don't hold up on
> mine, this is just the nature of such collaboration  :)
>
> > Did you have any thoughts on the XXX what to pass in for lxcpath in
> > lxc_init? Right now it just falls back to LOGPATH.
>
> No - that's a weird one, since lxc_init runs in the container.  If
> there were only system containers I'd say always use LOGPATH.
> However there are people (apparently :) who use container sharing the
> host's rootfs...
>
> lxc-execute does know the lxcpath.  Perhaps we can simply have
> src/lxc/execute.c:execute_start() look at handler->conf to see if a
> rootfs is set.  If rootfs is NOT set, then pass lxcpath along to
> lxc-init.  Then lxc-init can mostly do the same as the others?  (It
> doesn't use src/lxc/arguments.c, so you'd have to add lxcpath to
> options[] in lxc-init.c)

So I did this, only to realize that lxc-init is passing "none" for the
file anyway, so it currently doesn't intend to log. This makes me
think that passing NULL for lxcpath is the right thing to do in
this patch. If you want me to make it so lxc-init can log, I can do
that but I think it should be in a different change :)

--

Signed-off-by: Dwight Engen <dwight.engen@oracle.com>
Signed-off-by: Serge Hallyn <serge.hallyn@ubuntu.com>

src/lxc/log.c

@@ -35,15 +35,19 @@
 
 #include "log.h"
 #include "caps.h"
+#include "utils.h"
 
 #define LXC_LOG_PREFIX_SIZE	32
 #define LXC_LOG_BUFFER_SIZE	512
 
 int lxc_log_fd = -1;
 static char log_prefix[LXC_LOG_PREFIX_SIZE] = "lxc";
+static char *log_fname = NULL;
+/* command line values for logfile or logpriority should always override
+ * values from the configuration file or defaults
+ */
+static int lxc_logfile_specified = 0;
 static int lxc_loglevel_specified = 0;
-// if logfile was specifed on command line, it won't be overridden by lxc.logfile
-static int lxc_log_specified = 0;
 
 lxc_log_define(lxc_log, lxc);
 
@@ -119,12 +123,6 @@ struct lxc_log_category lxc_log_category_lxc = {
 };
 
 /*---------------------------------------------------------------------------*/
-extern void lxc_log_setprefix(const char *prefix)
-{
-	strncpy(log_prefix, prefix, sizeof(log_prefix));
-	log_prefix[sizeof(log_prefix) - 1] = 0;
-}
-
 static int build_dir(const char *name)
 {
 	char *n = strdup(name);  // because we'll be modifying it
@@ -180,28 +178,39 @@ static int log_open(const char *name)
 	return newfd;
 }
 
-static char *build_log_path(const char *name)
+/*
+ * 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);
 #endif
 	if (ret < 0 || ret >= len) {
 		free(p);
@@ -210,19 +219,67 @@ static char *build_log_path(const char *name)
 	return p;
 }
 
-int do_lxc_log_set_file(const char *fname, int from_default);
+/*
+ * This can be called:
+ *   1. when a program calls lxc_log_init with no logfile parameter (in which
+ *      case the default is used).  In this case lxc.logfile can override this.
+ *   2. when a program calls lxc_log_init with a logfile parameter.  In this
+ *	case we don't want lxc.logfile to override this.
+ *   3. When a lxc.logfile entry is found in config file.
+ */
+static int __lxc_log_set_file(const char *fname, int create_dirs)
+{
+	if (lxc_log_fd != -1) {
+		// we are overriding the default.
+		close(lxc_log_fd);
+		free(log_fname);
+	}
+
+#if USE_CONFIGPATH_LOGS
+	// we don't build_dir for the default if the default is
+	// i.e. /var/lib/lxc/$container/$container.log
+	if (create_dirs)
+#endif
+	if (build_dir(fname)) {
+		ERROR("failed to create dir for log file \"%s\" : %s", fname,
+		      strerror(errno));
+		return -1;
+	}
+
+	lxc_log_fd = log_open(fname);
+	if (lxc_log_fd == -1)
+		return -1;
+
+	log_fname = strdup(fname);
+	return 0;
+}
+
+static int _lxc_log_set_file(const char *name, const char *lxcpath, int create_dirs)
+{
+	char *logfile;
+	int ret;
+
+	logfile = build_log_path(name, lxcpath);
+	if (!logfile) {
+		ERROR("could not build log path");
+		return -1;
+	}
+	ret = __lxc_log_set_file(logfile, create_dirs);
+	free(logfile);
+	return ret;
+}
 
-/*---------------------------------------------------------------------------*/
 extern int lxc_log_init(const char *name, const char *file,
-			const char *priority, const char *prefix, int quiet)
+			const char *priority, const char *prefix, int quiet,
+			const char *lxcpath)
 {
 	int lxc_priority = LXC_LOG_PRIORITY_ERROR;
 	int ret;
-	char *tmpfile = NULL;
-	int want_lxc_log_specified = 0;
 
-	if (lxc_log_fd != -1)
+	if (lxc_log_fd != -1) {
+		WARN("lxc_log_init called with log already initialized");
 		return 0;
+	}
 
 	if (priority) {
 		lxc_loglevel_specified = 1;
@@ -241,38 +298,38 @@ extern int lxc_log_init(const char *name, const char *file,
 		lxc_log_category_lxc.appender->next = &log_appender_stderr;
 
 	if (prefix)
-		lxc_log_setprefix(prefix);
+		lxc_log_set_prefix(prefix);
 
-	if (file && strcmp(file, "none") == 0) {
-		return 0;
-	}
-
-	if (!file) {
-		tmpfile = build_log_path(name);
-		if (!tmpfile) {
-			ERROR("could not build log path");
-			return -1;
-		}
+	if (file) {
+		lxc_logfile_specified = 1;
+		if (strcmp(file, "none") == 0)
+			return 0;
+		ret = __lxc_log_set_file(file, 1);
 	} else {
-		want_lxc_log_specified = 1;
+		ret = -1;
+
+		/* try LOGPATH if lxcpath is the default */
+		if (strcmp(lxcpath, default_lxc_path()) == 0)
+			ret = _lxc_log_set_file(name, NULL, 0);
+
+		/* try in lxcpath */
+		if (ret < 0)
+			ret = _lxc_log_set_file(name, lxcpath, 1);
+
+		/* try LOGPATH in case its writable by the caller */
+		if (ret < 0)
+			ret = _lxc_log_set_file(name, NULL, 0);
 	}
 
-	ret = do_lxc_log_set_file(tmpfile ? tmpfile : file, !want_lxc_log_specified);
-
-	if (want_lxc_log_specified)
-		lxc_log_specified = 1;
 	/*
-	 * If !want_lxc_log_specified, that is, if the user did not request
-	 * this logpath, then ignore failures and continue logging to console
+	 * If !file, that is, if the user did not request this logpath, then
+	 * ignore failures and continue logging to console
 	 */
-	if (!want_lxc_log_specified && ret != 0) {
+	if (!file && ret != 0) {
 		INFO("Ignoring failure to open default logfile.");
 		ret = 0;
 	}
 
-	if (tmpfile)
-		free(tmpfile);
-
 	return ret;
 }
 
@@ -293,51 +350,6 @@ extern int lxc_log_set_level(int level)
 	return 0;
 }
 
-char *log_fname;  // default to NULL, set in lxc_log_set_file.
-/*
- * This can be called:
- *   1. when a program calls lxc_log_init with no logfile parameter (in which
- *      case the default is used).  In this case lxc.logfile can override this.
- *   2. when a program calls lxc_log_init with a logfile parameter.  In this
- *	case we don't want lxc.logfile to override this.
- *   3. When a lxc.logfile entry is found in config file.
- */
-int do_lxc_log_set_file(const char *fname, int from_default)
-{
-	if (lxc_log_specified) {
-		INFO("lxc.logfile overridden by command line");
-		return 0;
-	}
-	if (lxc_log_fd != -1) {
-		// we are overriding the default.
-		close(lxc_log_fd);
-		free(log_fname);
-	}
-
-#if USE_CONFIGPATH_LOGS
-	// we don't build_dir for the default if the default is
-	// i.e. /var/lib/lxc/$container/$container.log
-	if (!from_default)
-#endif
-	if (build_dir(fname)) {
-		ERROR("failed to create dir for log file \"%s\" : %s", fname,
-		      strerror(errno));
-		return -1;
-	}
-
-	lxc_log_fd = log_open(fname);
-	if (lxc_log_fd == -1)
-		return -1;
-
-	log_fname = strdup(fname);
-	return 0;
-}
-
-extern int lxc_log_set_file(const char *fname)
-{
-	return do_lxc_log_set_file(fname, 0);
-}
-
 extern int lxc_log_get_level(void)
 {
 	if (!lxc_loglevel_specified)
@@ -345,7 +357,30 @@ extern int lxc_log_get_level(void)
 	return lxc_log_category_lxc.priority;
 }
 
+/*
+ * This is called when we read a lxc.logfile entry in a lxc.conf file.  This
+ * happens after processing command line arguments, which override the .conf
+ * settings.  So only set the file if previously unset.
+ */
+extern int lxc_log_set_file(const char *fname)
+{
+	if (lxc_logfile_specified)
+		return 0;
+	return __lxc_log_set_file(fname, 0);
+}
+
 extern const char *lxc_log_get_file(void)
 {
 	return log_fname;
 }
+
+extern void lxc_log_set_prefix(const char *prefix)
+{
+	strncpy(log_prefix, prefix, sizeof(log_prefix));
+	log_prefix[sizeof(log_prefix) - 1] = 0;
+}
+
+extern const char *lxc_log_get_prefix(void)
+{
+	return log_prefix;
+}

src/lxc/log.h

@@ -288,11 +288,13 @@ extern struct lxc_log_category lxc_log_category_lxc;
 extern int lxc_log_fd;
 
 extern int lxc_log_init(const char *name, const char *file,
-			const char *priority, const char *prefix, int quiet);
+			const char *priority, const char *prefix, int quiet,
+			const char *lxcpath);
 
-extern void lxc_log_setprefix(const char *a_prefix);
-extern int lxc_log_set_level(int level);
 extern int lxc_log_set_file(const char *fname);
-extern int lxc_log_get_level(void);
+extern int lxc_log_set_level(int level);
+extern void lxc_log_set_prefix(const char *prefix);
 extern const char *lxc_log_get_file(void);
+extern int lxc_log_get_level(void);
+extern const char *lxc_log_get_prefix(void);
 #endif

src/lxc/lxc_attach.c

@@ -292,7 +292,7 @@ int main(int argc, char *argv[])
 		return ret;
 
 	ret = lxc_log_init(my_args.name, my_args.log_file, my_args.log_priority,
-			   my_args.progname, my_args.quiet);
+			   my_args.progname, my_args.quiet, my_args.lxcpath);
 	if (ret)
 		return ret;
 

src/lxc/lxc_cgroup.c

@@ -69,7 +69,7 @@ int main(int argc, char *argv[])
 		return -1;
 
 	if (lxc_log_init(my_args.name, my_args.log_file, my_args.log_priority,
-			 my_args.progname, my_args.quiet))
+			 my_args.progname, my_args.quiet, my_args.lxcpath))
 		return -1;
 
 	state_object = my_args.argv[0];

src/lxc/lxc_checkpoint.c

@@ -116,7 +116,7 @@ int main(int argc, char *argv[])
 		return ret;
 
 	ret = lxc_log_init(my_args.name, my_args.log_file, my_args.log_priority,
-			   my_args.progname, my_args.quiet);
+			   my_args.progname, my_args.quiet, my_args.lxcpath);
 	if (ret)
 		return ret;
 

src/lxc/lxc_console.c

@@ -192,7 +192,7 @@ int main(int argc, char *argv[])
 		return -1;
 
 	err = lxc_log_init(my_args.name, my_args.log_file, my_args.log_priority,
-			   my_args.progname, my_args.quiet);
+			   my_args.progname, my_args.quiet, my_args.lxcpath);
 	if (err)
 		return -1;
 

src/lxc/lxc_execute.c

@@ -101,7 +101,7 @@ int main(int argc, char *argv[])
 		return -1;
 
 	if (lxc_log_init(my_args.name, my_args.log_file, my_args.log_priority,
-			 my_args.progname, my_args.quiet))
+			 my_args.progname, my_args.quiet, my_args.lxcpath))
 		return -1;
 
 	/* rcfile is specified in the cli option */

src/lxc/lxc_freeze.c

@@ -55,7 +55,7 @@ int main(int argc, char *argv[])
 		return -1;
 
 	if (lxc_log_init(my_args.name, my_args.log_file, my_args.log_priority,
-			 my_args.progname, my_args.quiet))
+			 my_args.progname, my_args.quiet, my_args.lxcpath))
 		return -1;
 
 	return lxc_freeze(my_args.name, my_args.lxcpath);

src/lxc/lxc_info.c

@@ -80,7 +80,7 @@ int main(int argc, char *argv[])
 		return 1;
 
 	if (lxc_log_init(my_args.name, my_args.log_file, my_args.log_priority,
-			 my_args.progname, my_args.quiet))
+			 my_args.progname, my_args.quiet, my_args.lxcpath))
 		return 1;
 
 	if (!state && !pid)

src/lxc/lxc_init.c

@@ -78,7 +78,7 @@ int main(int argc, char *argv[])
 	if (lxc_caps_init())
 		exit(err);
 
-	if (lxc_log_init(NULL, "none", 0, basename(argv[0]), quiet))
+	if (lxc_log_init(NULL, "none", 0, basename(argv[0]), quiet, NULL))
 		exit(err);
 
 	if (!argv[optind]) {

src/lxc/lxc_kill.c

@@ -62,7 +62,7 @@ int main(int argc, char *argv[], char *envp[])
 		return ret;
 
 	ret = lxc_log_init(my_args.name, my_args.log_file, my_args.log_priority,
-			   my_args.progname, my_args.quiet);
+			   my_args.progname, my_args.quiet, my_args.lxcpath);
 	if (ret)
 		return ret;
 

src/lxc/lxc_monitor.c

@@ -66,7 +66,7 @@ int main(int argc, char *argv[])
 		return -1;
 
 	if (lxc_log_init(my_args.name, my_args.log_file, my_args.log_priority,
-			 my_args.progname, my_args.quiet))
+			 my_args.progname, my_args.quiet, my_args.lxcpath))
 		return -1;
 
 	len = strlen(my_args.name) + 3;

src/lxc/lxc_monitord.c

@@ -343,7 +343,7 @@ int main(int argc, char *argv[])
 	if (ret < 0 || ret >= sizeof(logpath))
 		return EXIT_FAILURE;
 
-	ret = lxc_log_init(NULL, logpath, "NOTICE", "lxc-monitord", 0);
+	ret = lxc_log_init(NULL, logpath, "NOTICE", "lxc-monitord", 0, lxcpath);
 	if (ret)
 		return ret;
 

src/lxc/lxc_restart.c

@@ -124,7 +124,7 @@ int main(int argc, char *argv[])
 		return -1;
 
 	if (lxc_log_init(my_args.name, my_args.log_file, my_args.log_priority,
-			 my_args.progname, my_args.quiet))
+			 my_args.progname, my_args.quiet, my_args.lxcpath))
 		return -1;
 
 	/* rcfile is specified in the cli option */

src/lxc/lxc_start.c

@@ -165,7 +165,7 @@ int main(int argc, char *argv[])
 		args = my_args.argv;
 
 	if (lxc_log_init(my_args.name, my_args.log_file, my_args.log_priority,
-			 my_args.progname, my_args.quiet))
+			 my_args.progname, my_args.quiet, my_args.lxcpath))
 		return err;
 
 	/* rcfile is specified in the cli option */

src/lxc/lxc_stop.c

@@ -55,7 +55,7 @@ int main(int argc, char *argv[])
 		return -1;
 
 	if (lxc_log_init(my_args.name, my_args.log_file, my_args.log_priority,
-			 my_args.progname, my_args.quiet))
+			 my_args.progname, my_args.quiet, my_args.lxcpath))
 		return -1;
 
 	return lxc_stop(my_args.name, my_args.lxcpath);

src/lxc/lxc_unfreeze.c

@@ -54,7 +54,7 @@ int main(int argc, char *argv[])
 		return -1;
 
 	if (lxc_log_init(my_args.name, my_args.log_file, my_args.log_priority,
-			 my_args.progname, my_args.quiet))
+			 my_args.progname, my_args.quiet, my_args.lxcpath))
 		return -1;
 
 	return lxc_unfreeze(my_args.name, my_args.lxcpath);

src/lxc/lxc_wait.c

@@ -84,7 +84,7 @@ int main(int argc, char *argv[])
 		return -1;
 
 	if (lxc_log_init(my_args.name, my_args.log_file, my_args.log_priority,
-			 my_args.progname, my_args.quiet))
+			 my_args.progname, my_args.quiet, my_args.lxcpath))
 		return -1;
 
 	return lxc_wait(strdup(my_args.name), my_args.states, my_args.timeout, my_args.lxcpath);

src/lxc/lxccontainer.c

@@ -1105,7 +1105,7 @@ struct lxc_container *lxc_container_new(const char *name, const char *configpath
 	c->set_config_path = lxcapi_set_config_path;
 
 	/* we'll allow the caller to update these later */
-	if (lxc_log_init(NULL, "none", NULL, "lxc_container", 0)) {
+	if (lxc_log_init(NULL, "none", NULL, "lxc_container", 0, c->config_path)) {
 		fprintf(stderr, "failed to open log\n");
 		goto err;
 	}