From: "Daniel P. Berrange" <berrange@redhat.com> When booting a virtual machine with a kernel/initrd it is possible to pass command line arguments using the <cmdline>...args...</cmdline> element in the guest XML. These appear to the kernel / init process in /proc/cmdline. When booting a container we do not have a custom /proc/cmdline, but we can easily set an environment variable for it. Ideally we could pass individual arguments to the init process as a regular set of 'char *argv[]' parameters, but that would involve libvirt parsing the <cmdline> XML text. This can easily be added later, even if we add the env variable now * docs/drvlxc.html.in: Document env variables passed to LXC * src/conf/domain_conf.c: Add <cmdline> to be parsed for guests of type='exe' * src/lxc/lxc_container.c: Set LIBVIRT_LXC_CMDLINE env var --- docs/drvlxc.html.in | 17 +++++++++++++++++ src/conf/domain_conf.c | 1 + src/lxc/lxc_container.c | 2 ++ 3 files changed, 20 insertions(+), 0 deletions(-) diff --git a/docs/drvlxc.html.in b/docs/drvlxc.html.in index 5ce218d..47837d1 100644 --- a/docs/drvlxc.html.in +++ b/docs/drvlxc.html.in @@ -39,6 +39,23 @@ driver. On such kernels, it may be neccessary to unmount the blkio controller. </p> +<h2>Environment setup for the container init</h2> + +<p> +When the container "init" process is started, it will be given several useful +environment variables. +</p> + +<dl> +<dt>LIBVIRT_LXC_NAME</dt> +<dd>The name assigned to the container by libvirt</dd> +<dt>LIBVIRT_LXC_UUID</dt> +<dd>The UUID assigned to the container by libvirt</dd> +<dt>LIBVIRT_LXC_CMDLINE</dt> +<dd>The unparsed command line arguments specified in the container configuration</dd> +</dl> + + <h3>Example config version 1</h3> <p></p> <pre> diff --git a/src/conf/domain_conf.c b/src/conf/domain_conf.c index 6fb1888..0f751ca 100644 --- a/src/conf/domain_conf.c +++ b/src/conf/domain_conf.c @@ -6833,6 +6833,7 @@ static virDomainDefPtr virDomainDefParseXML(virCapsPtr caps, goto error; } } + def->os.cmdline = virXPathString("string(./os/cmdline[1])", ctxt); } if (STREQ(def->os.type, "xen") || diff --git a/src/lxc/lxc_container.c b/src/lxc/lxc_container.c index 787df9a..69cea8e 100644 --- a/src/lxc/lxc_container.c +++ b/src/lxc/lxc_container.c @@ -116,6 +116,8 @@ static virCommandPtr lxcContainerBuildInitCmd(virDomainDefPtr vmDef) virCommandAddEnvString(cmd, "TERM=linux"); virCommandAddEnvPair(cmd, "LIBVIRT_LXC_UUID", uuidstr); virCommandAddEnvPair(cmd, "LIBVIRT_LXC_NAME", vmDef->name); + if (vmDef->os.cmdline) + virCommandAddEnvPair(cmd, "LIBVIRT_LXC_CMDLINE", vmDef->os.cmdline); return cmd; } -- 1.7.6.2