[lxc-devel] [PATCH] Remove MAKEDEV call, add autodev hooks, add environment variables for hook scripts.
Michael H. Warfield
mhw at WittsEnd.com
Thu Jan 10 04:38:14 UTC 2013
And now for round two of this patch...
On Wed, 2013-01-09 at 15:26 -0600, Serge Hallyn wrote:
> Quoting Michael H. Warfield (mhw at WittsEnd.com):
> > Ok, all!
> >
> > Here's the patch I promised Serge in the "[PATCH] Support MS_SHARED /"
> > thread to address the mayhem that calling MAKEDEV was causing.
> >
> > This is a straw-man patch. This is the first patch I've submitted to
> > this project but I plagerized like hell, so I hope I got the coding
> > style matched. Look it over and suggest changes. It adds some features
> > and changes some features. If you don't like what I did, no problem. I
> > probably did somethings that some people may consider "suboptimal". My
> > feelings won't be hurt if you say so.
> >
> > This patch does several things...
> >
> > 1) Removes run_makedev() and the call to it from conf.c per discussion.
> >
> > 2) Adds an lxc.hook.autodev hook.
> >
> > Note: This hook is very close (one routine level abstracted) from where
> > the run_makedev was called. Anyone really rrreeeaaalllyyy needing
> > MAKEDEV can add it in with a small shim script to do whatever they want
> > under whatever distro they're using, so no functionality is lost there.
> >
> > 3) Added a number of environment variables for all the hook scripts to
> > reference to assist in execution. Things like LXC_ROOTFS_MOUNT could be
> > very useful but others were added as well. Room for more if anyone has
> > an itch. All in one spot in lxc_start.c.
> >
> > 4) clearenv and putenv( "container=lxc" ) calls were moved to just after
> > the "start" hook in the container just prior to actually firing up the
> > container so we could use environment variables prior to that and have
> > them flushed them before firing up init. Nice side effect is that you
> > can define environment variables and then call lxc-start and have them
> > show up in those hooks scripts.
> >
> > 5) I actually DID update the man page for lxc.conf! I guess I lied when
> > I said I wouldn't get that done.
> >
> > Now for the ugly side...
> >
> > I don't think where I stuck all those "setenv" calls is the best place
> > in lxc_start.c but it's where all the variables I needed where set in
> Right, it should be done in start.c, since lxc-execute won't hit them
> if they're in lxc-start.c
> Perhaps you can get the logfile using readlink on
> /proc/self/fd/$(lxc_conf->lxc_log_fd) ? The rcfile could be
> added to struct conf for you to use.
The lxc_conf.logfile and lxc_conf.loglevel in the lxc_conf structure do
not seem to be related to the -l log priority or the -o log output.
I've left them in for the time being but removed them from the
documentation since the lxc.logfile and lxc.logpriority options in the
config file appear to be undocumented.
I added the rcfile to the lxc_conf structure as suggested and moved the
setenv bundle from lxc-start.c over to start.c just prior to calling
run_lxc_hooks for the pre-start hook.
I also spotted an error on my part that I wasn't checking for NULLs in a
couple of those setenv options that could have been NULL. Added checks
for that. Glad I caught it first. I know better.
> Other than that, patch looks great, thanks.
Round 2 patch below my signature block.
> -serge
Regards,
Mike
--
Michael H. Warfield (AI4NB) | (770) 985-6132 | mhw at WittsEnd.com
/\/\|=mhw=|\/\/ | (678) 463-0932 | http://www.wittsend.com/mhw/
NIC whois: MHW9 | An optimist believes we live in the best of all
PGP Key: 0x674627FF | possible worlds. A pessimist is sure of it!
--
diff --git a/doc/lxc.conf.sgml.in b/doc/lxc.conf.sgml.in
index 96dea89..1298143 100644
--- a/doc/lxc.conf.sgml.in
+++ b/doc/lxc.conf.sgml.in
@@ -510,6 +510,10 @@ Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
rootfs. If lxc.autodev is set to 1, then after mounting the container's
rootfs LXC will mount a fresh tmpfs under <filename>/dev</filename>
(limited to 100k) and fill in a minimal set of initial devices.
+ This is generally required when starting a container containing
+ a "systemd" based "init" but may be optional at other times. Addional
+ devices in the containers /dev directory may be created through the
+ use of the <option>lxc.hook.autodev</option> hook.
</para>
<variablelist>
<varlistentry>
@@ -737,6 +741,27 @@ Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
<variablelist>
<varlistentry>
<term>
+ <option>lxc.hook.autodev</option>
+ </term>
+ <listitem>
+ <para>
+ A hook to be run in the container's namespace after
+ mounting has been done and after any mount hooks have
+ run, but before the pivot_root, if
+ <option>lxc.autodev</option> == 1.
+ The purpose of this hook is to assist in populating the
+ /dev directory of the container when using the autodev
+ option for systemd based containers. The container's /dev
+ directory is relative to the
+ ${<option>LXC_ROOTFS_MOUNT</option>} environment
+ variable available when the hook is run.
+ </para>
+ </listitem>
+ </varlistentry>
+ </variablelist>
+ <variablelist>
+ <varlistentry>
+ <term>
<option>lxc.hook.start</option>
</term>
<listitem>
@@ -763,6 +788,103 @@ Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
</variablelist>
</refsect2>
+ <refsect2>
+ <title>Startup hooks Environment Variables</title>
+ <para>
+ A number of environment variables are made available to the startup
+ hooks to provide configuration information and assist in the
+ functioning of the hooks. Not all variables are valid in all
+ contexts. In particular, all paths are relative to the host system
+ and, as such, not valid during the <option>lxc.hook.start</option> hook.
+ </para>
+ <variablelist>
+ <varlistentry>
+ <term>
+ <option>LXC_NAME</option>
+ </term>
+ <listitem>
+ <para>
+ The LXC name of the container. Useful for logging messages
+ in commmon log environments. [<option>-n</option>]
+ </para>
+ </listitem>
+ </varlistentry>
+ </variablelist>
+ <variablelist>
+ <varlistentry>
+ <term>
+ <option>LXC_CONFIG_FILE</option>
+ </term>
+ <listitem>
+ <para>
+ Host relative path to the container configuration file. This
+ gives the container to reference the original, top level,
+ configuration file for the container in order to locate any
+ addotional configuration information not otherwise made
+ available. [<option>-f</option>]
+ </para>
+ </listitem>
+ </varlistentry>
+ </variablelist>
+ <variablelist>
+ <varlistentry>
+ <term>
+ <option>LXC_CONSOLE</option>
+ </term>
+ <listitem>
+ <para>
+ The path to the console output of the container if not NULL.
+ [<option>-c</option>] [<option>lxc.console</option>]
+ </para>
+ </listitem>
+ </varlistentry>
+ </variablelist>
+ <variablelist>
+ <varlistentry>
+ <term>
+ <option>LXC_CONSOLE_LOGPATH</option>
+ </term>
+ <listitem>
+ <para>
+ The path to the console log output of the container if not NULL.
+ [<option>-L</option>]
+ </para>
+ </listitem>
+ </varlistentry>
+ </variablelist>
+ <variablelist>
+ <varlistentry>
+ <term>
+ <option>LXC_ROOTFS_MOUNT</option>
+ </term>
+ <listitem>
+ <para>
+ The mount location to which the container is initially bound.
+ This will be the host relative path to the container rootfs
+ for the container instance being started and is where changes
+ should be made for that instance.
+ [<option>lxc.rootfs.mount</option>]
+ </para>
+ </listitem>
+ </varlistentry>
+ </variablelist>
+ <variablelist>
+ <varlistentry>
+ <term>
+ <option>LXC_ROOTFS_PATH</option>
+ </term>
+ <listitem>
+ <para>
+ The host relative path to the container root which has been
+ mounted to the rootfs.mount location.
+ [<option>lxc.rootfs</option>]
+ </para>
+ </listitem>
+ </varlistentry>
+ </variablelist>
+
+ </refsect2>
+
</refsect1>
<refsect1>
diff --git a/src/lxc/conf.c b/src/lxc/conf.c
index 1c02850..699011a 100644
--- a/src/lxc/conf.c
+++ b/src/lxc/conf.c
@@ -116,7 +116,7 @@ lxc_log_define(lxc_conf, lxc);
#endif
char *lxchook_names[NUM_LXC_HOOKS] = {
- "pre-start", "pre-mount", "mount", "start", "post-stop" };
+ "pre-start", "pre-mount", "mount", "autodev", "start", "post-stop" };
extern int pivot_root(const char * new_root, const char * put_old);
@@ -913,33 +913,6 @@ static int mount_autodev(char *root)
return 0;
}
-/*
- * Try to run MAKEDEV console in the container. If something fails,
- * continue anyway as it should not be detrimental to the container.
- * This makes sure that things like /dev/vcs* exist.
- * (Pass devpath in to reduce stack usage)
- */
-static void run_makedev(char *devpath)
-{
- int curd;
- int ret;
-
- curd = open(".", O_RDONLY);
- if (curd < 0)
- return;
- ret = chdir(devpath);
- if (ret) {
- close(curd);
- return;
- }
- if (run_buffer("/sbin/MAKEDEV console"))
- INFO("Error running MAKEDEV console in %s", devpath);
- ret = fchdir(curd);
- if (ret)
- INFO("Error returning to original directory: expect breakage");
- close(curd);
-}
-
struct lxc_devs {
char *name;
mode_t mode;
@@ -971,8 +944,7 @@ static int setup_autodev(char *root)
if (ret < 0 || ret >= MAXPATHLEN) {
ERROR("Error calculating container /dev location");
return -1;
- } else
- run_makedev(path);
+ }
INFO("Populating /dev under %s\n", root);
cmask = umask(S_IXUSR | S_IXGRP | S_IXOTH);
@@ -2553,6 +2525,10 @@ int lxc_setup(const char *name, struct lxc_conf *lxc_conf)
}
if (lxc_conf->autodev) {
+ if (run_lxc_hooks(name, "autodev", lxc_conf)) {
+ ERROR("failed to run autodev hooks for container '%s'.", name);
+ return -1;
+ }
if (setup_autodev(lxc_conf->rootfs.mount)) {
ERROR("failed to populate /dev in the container");
return -1;
@@ -2628,6 +2604,8 @@ int run_lxc_hooks(const char *name, char *hook, struct lxc_conf *conf)
which = LXCHOOK_PREMOUNT;
else if (strcmp(hook, "mount") == 0)
which = LXCHOOK_MOUNT;
+ else if (strcmp(hook, "autodev") == 0)
+ which = LXCHOOK_AUTODEV;
else if (strcmp(hook, "start") == 0)
which = LXCHOOK_START;
else if (strcmp(hook, "post-stop") == 0)
diff --git a/src/lxc/conf.h b/src/lxc/conf.h
index b576893..45161e1 100644
--- a/src/lxc/conf.h
+++ b/src/lxc/conf.h
@@ -213,8 +213,8 @@ struct lxc_rootfs {
#endif
*/
enum lxchooks {
- LXCHOOK_PRESTART, LXCHOOK_PREMOUNT, LXCHOOK_MOUNT, LXCHOOK_START,
- LXCHOOK_POSTSTOP, NUM_LXC_HOOKS};
+ LXCHOOK_PRESTART, LXCHOOK_PREMOUNT, LXCHOOK_MOUNT, LXCHOOK_AUTODEV,
+ LXCHOOK_START, LXCHOOK_POSTSTOP, NUM_LXC_HOOKS};
extern char *lxchook_names[NUM_LXC_HOOKS];
struct saved_nic {
@@ -257,6 +257,7 @@ struct lxc_conf {
#endif
int maincmd_fd;
int autodev; // if 1, mount and fill a /dev at start
+ char *rcfile; // Copy of the top level rcfile we read
};
int run_lxc_hooks(const char *name, char *hook, struct lxc_conf *conf);
diff --git a/src/lxc/confile.c b/src/lxc/confile.c
index 1d87227..8cef8be 100644
--- a/src/lxc/confile.c
+++ b/src/lxc/confile.c
@@ -104,6 +104,7 @@ static struct lxc_config_t config[] = {
{ "lxc.hook.pre-start", config_hook },
{ "lxc.hook.pre-mount", config_hook },
{ "lxc.hook.mount", config_hook },
+ { "lxc.hook.autodev", config_hook },
{ "lxc.hook.start", config_hook },
{ "lxc.hook.post-stop", config_hook },
{ "lxc.network.type", config_network_type },
@@ -821,6 +822,8 @@ static int config_hook(const char *key, const char *value,
return add_hook(lxc_conf, LXCHOOK_PRESTART, copy);
else if (strcmp(key, "lxc.hook.pre-mount") == 0)
return add_hook(lxc_conf, LXCHOOK_PREMOUNT, copy);
+ else if (strcmp(key, "lxc.hook.autodev") == 0)
+ return add_hook(lxc_conf, LXCHOOK_AUTODEV, copy);
else if (strcmp(key, "lxc.hook.mount") == 0)
return add_hook(lxc_conf, LXCHOOK_MOUNT, copy);
else if (strcmp(key, "lxc.hook.start") == 0)
@@ -1265,6 +1268,10 @@ int lxc_config_readline(char *buffer, struct lxc_conf *conf)
int lxc_config_read(const char *file, struct lxc_conf *conf)
{
+ /* Catch only the top level config file name in the structure */
+ if( ! conf->rcfile ) {
+ conf->rcfile = strdup( file );
+ }
return lxc_file_for_each_line(file, parse_line, conf);
}
diff --git a/src/lxc/lxc_start.c b/src/lxc/lxc_start.c
index 184fb04..a97dcca 100644
--- a/src/lxc/lxc_start.c
+++ b/src/lxc/lxc_start.c
@@ -168,15 +168,6 @@ int main(int argc, char *argv[])
my_args.progname, my_args.quiet))
return err;
- if (clearenv()) {
- SYSERROR("failed to clear environment");
- /* don't error out though */
- }
- if (putenv("container=lxc")) {
- SYSERROR("failed to set environment variable");
- return err;
- }
-
/* rcfile is specified in the cli option */
if (my_args.rcfile)
rcfile = (char *)my_args.rcfile;
diff --git a/src/lxc/start.c b/src/lxc/start.c
index 82a74d8..f3a4bd3 100644
--- a/src/lxc/start.c
+++ b/src/lxc/start.c
@@ -391,6 +391,40 @@ struct lxc_handler *lxc_init(const char *name, struct lxc_conf *conf)
goto out_free_name;
}
+ /* Start of environment variable setup for hooks */
+ if (setenv("LXC_NAME", name, 1)) {
+ SYSERROR("failed to set environment variable for container name");
+ }
+ if (setenv("LXC_CONFIG_FILE", conf->rcfile, 1)) {
+ SYSERROR("failed to set environment variable for config path");
+ }
+ if (setenv("LXC_ROOTFS_MOUNT", conf->rootfs.mount, 1)) {
+ SYSERROR("failed to set environment variable for rootfs mount");
+ }
+ if (setenv("LXC_ROOTFS_PATH", conf->rootfs.path, 1)) {
+ SYSERROR("failed to set environment variable for rootfs mount");
+ }
+ if (conf->console.path && setenv("LXC_CONSOLE", conf->console.path, 1)) {
+ SYSERROR("failed to set environment variable for console path");
+ }
+ if (conf->console.log_path && setenv("LXC_CONSOLE_LOGPATH", conf->console.log_path, 1)) {
+ SYSERROR("failed to set environment variable for console log");
+ }
+ /* Not quite sure right now what these next two actually do but
+ * leaving them in, just not documenting them, for the moment just
+ * in case they are a work in progress somewhere else. */
+ if (conf->logfile && setenv("LXC_LOGPATH", conf->logfile, 1)) {
+ SYSERROR("failed to set environment variable for console log");
+ }
+ {
+ char loglevel[16];
+ snprintf( loglevel, 14, "%d", conf->loglevel );
+ if (setenv("LXC_LOGLEVEL", loglevel, 1)) {
+ SYSERROR("failed to set environment variable for log level mount");
+ }
+ }
+ /* End of environment variable setup for hooks */
+
if (run_lxc_hooks(name, "pre-start", conf)) {
ERROR("failed to run pre-start hooks for container '%s'.", name);
goto out_aborting;
@@ -575,6 +609,21 @@ static int do_start(void *data)
goto out_warn_father;
}
+ /* The clearenv() and putenv() calls have been moved here
+ * to allow us to use enviroment variables passed to the various
+ * hooks, such as the start hook above. Not all of the
+ * variables like CONFIG_PATH or ROOTFS are valid in this
+ * context but others are. */
+ if (clearenv()) {
+ SYSERROR("failed to clear environment");
+ /* don't error out though */
+ }
+
+ if (putenv("container=lxc")) {
+ SYSERROR("failed to set environment variable");
+ return -1;
+ }
+
close(handler->sigfd);
/* after this call, we are in error because this
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