From c4cafa080c8beb9a34a1fecff9331d84385f6440 Mon Sep 17 00:00:00 2001
From: Serge Hallyn <serge.hallyn@ubuntu.com>
Date: Thu, 31 Dec 2015 17:43:15 -0800
Subject: [PATCH] add LXC_CGNS_AWARE env variable for mount hooks

This way the lxcfs mount hook can know whether lxc knows about
cgroup namespaces.

Signed-off-by: Serge Hallyn <serge.hallyn@ubuntu.com>
---
 doc/lxc.container.conf.sgml.in | 16 ++++++++++++++++
 src/lxc/start.c                |  3 +++
 2 files changed, 19 insertions(+)

diff --git a/doc/lxc.container.conf.sgml.in b/doc/lxc.container.conf.sgml.in
index 1e702c717..18ad924a3 100644
--- a/doc/lxc.container.conf.sgml.in
+++ b/doc/lxc.container.conf.sgml.in
@@ -1593,6 +1593,22 @@ mknod errno 0
           </listitem>
         </varlistentry>
       </variablelist>
+      <variablelist>
+        <varlistentry>
+          <term>
+            <option>LXC_CGNS_AWARE</option>
+          </term>
+          <listitem>
+            <para>
+	      If unset, then this version of lxc is not aware of cgroup
+	      namespaces.  If set, it will be set to 1, and lxc is aware
+	      of cgroup namespaces.  Note this does not guarantee that
+	      cgroup namespaces are enabled in the kernel.  This is used
+	      by the lxcfs mount hook.
+            </para>
+          </listitem>
+        </varlistentry>
+      </variablelist>
     </refsect2>
     <refsect2>
     <title>Logging</title>
diff --git a/src/lxc/start.c b/src/lxc/start.c
index 6d4d2c211..0d91eb394 100644
--- a/src/lxc/start.c
+++ b/src/lxc/start.c
@@ -451,6 +451,9 @@ struct lxc_handler *lxc_init(const char *name, struct lxc_conf *conf, const char
 	if (conf->console.log_path && setenv("LXC_CONSOLE_LOGPATH", conf->console.log_path, 1)) {
 		SYSERROR("failed to set environment variable for console log");
 	}
+	if (setenv("LXC_CGNS_AWARE", "1", 1)) {
+		SYSERROR("failed to set LXC_CGNS_AWARE environment variable");
+	}
 	/* End of environment variable setup for hooks */
 
 	if (run_lxc_hooks(name, "pre-start", conf, handler->lxcpath, NULL)) {