lxc: allow user to specify command working directory

Some containers may want the application to run in a special directory.
Add <initdir> element in the domain configuration to handle this case
and use it in the lxc driver.
Reviewed-by: NDaniel P. Berrange <berrange@redhat.com>

docs/formatdomain.html.in

@@ -330,6 +330,10 @@
       To set environment variables, use the <code>initenv</code> element, one
       for each variable.
     </p>
+    <p>
+      To set a custom work directory for the init, use the <code>initdir</code>
+      element.
+    </p>
 
     <pre>
 &lt;os&gt;
@@ -338,6 +342,7 @@
   &lt;initarg&gt;--unit&lt;/initarg&gt;
   &lt;initarg&gt;emergency.service&lt;/initarg&gt;
   &lt;initenv name='MYENV'&gt;some value&lt;/initenv&gt;
+  &lt;initdir&gt;/my/custom/cwd&lt;/initdir&gt;
 &lt;/os&gt;
     </pre>
 

docs/schemas/domaincommon.rng

@@ -395,6 +395,11 @@
             <text/>
           </element>
         </zeroOrMore>
+        <optional>
+          <element name="initdir">
+            <ref name="absFilePath"/>
+          </element>
+        </optional>
       </interleave>
     </element>
   </define>

src/conf/domain_conf.c

@@ -2876,6 +2876,7 @@ void virDomainDefFree(virDomainDefPtr def)
     VIR_FREE(def->os.initargv);
     for (i = 0; def->os.initenv && def->os.initenv[i]; i++)
         VIR_FREE(def->os.initenv[i]);
+    VIR_FREE(def->os.initdir);
     VIR_FREE(def->os.initenv);
     VIR_FREE(def->os.kernel);
     VIR_FREE(def->os.initrd);
@@ -17068,6 +17069,7 @@ virDomainDefParseBootOptions(virDomainDefPtr def,
     if (def->os.type == VIR_DOMAIN_OSTYPE_EXE) {
         def->os.init = virXPathString("string(./os/init[1])", ctxt);
         def->os.cmdline = virXPathString("string(./os/cmdline[1])", ctxt);
+        def->os.initdir = virXPathString("string(./os/initdir[1])", ctxt);
 
         if ((n = virXPathNodeSet("./os/initarg", ctxt, &nodes)) < 0)
             goto error;
@@ -24953,6 +24955,9 @@ virDomainDefFormatInternal(virDomainDefPtr def,
     for (i = 0; def->os.initenv && def->os.initenv[i]; i++)
         virBufferAsprintf(buf, "<initenv name='%s'>%s</initenv>\n",
                           def->os.initenv[i]->name, def->os.initenv[i]->value);
+    if (def->os.initdir)
+        virBufferEscapeString(buf, "<initdir>%s</initdir>\n",
+                              def->os.initdir);
     if (def->os.loader)
         virDomainLoaderDefFormat(buf, def->os.loader);
     virBufferEscapeString(buf, "<kernel>%s</kernel>\n",

src/conf/domain_conf.h

@@ -1869,6 +1869,7 @@ struct _virDomainOSDef {
     char *init;
     char **initargv;
     virDomainOSEnvPtr *initenv;
+    char *initdir;
     char *kernel;
     char *initrd;
     char *cmdline;

src/lxc/lxc_container.c

@@ -245,6 +245,8 @@ static virCommandPtr lxcContainerBuildInitCmd(virDomainDefPtr vmDef,
     virCommandAddEnvPair(cmd, "LIBVIRT_LXC_NAME", vmDef->name);
     if (vmDef->os.cmdline)
         virCommandAddEnvPair(cmd, "LIBVIRT_LXC_CMDLINE", vmDef->os.cmdline);
+    if (vmDef->os.initdir)
+        virCommandSetWorkingDirectory(cmd, vmDef->os.initdir);
 
     for (i = 0; vmDef->os.initenv[i]; i++) {
         virCommandAddEnvPair(cmd, vmDef->os.initenv[i]->name,

tests/lxcxml2xmldata/lxc-initdir.xml

+<domain type='lxc'>
+  <name>jessie</name>
+  <uuid>e21987a5-e98e-9c99-0e35-803e4d9ad1fe</uuid>
+  <memory unit='KiB'>1048576</memory>
+  <currentMemory unit='KiB'>1048576</currentMemory>
+  <vcpu placement='static'>1</vcpu>
+  <resource>
+    <partition>/machine</partition>
+  </resource>
+  <os>
+    <type arch='x86_64'>exe</type>
+    <init>/sbin/sh</init>
+    <initdir>/path/to/pwd</initdir>
+  </os>
+  <clock offset='utc'/>
+  <on_poweroff>destroy</on_poweroff>
+  <on_reboot>restart</on_reboot>
+  <on_crash>restart</on_crash>
+  <devices>
+    <emulator>/usr/libexec/libvirt_lxc</emulator>
+    <filesystem type='mount' accessmode='passthrough'>
+      <source dir='/mach/jessie'/>
+      <target dir='/'/>
+    </filesystem>
+    <console type='pty'>
+      <target type='lxc' port='0'/>
+    </console>
+  </devices>
+  <seclabel type='none'/>
+</domain>

tests/lxcxml2xmltest.c

@@ -99,6 +99,7 @@ mymain(void)
     DO_TEST_FULL("filesystem-root", 0, false,
                  VIR_DOMAIN_DEF_PARSE_SKIP_OSTYPE_CHECKS);
     DO_TEST("initenv");
+    DO_TEST("initdir");
 
     virObjectUnref(caps);
     virObjectUnref(xmlopt);