Overview

The Bare Metal Service supports putting nodes in rescue mode using
hardware types that support rescue interfaces. The hardware types
utilizing ironic-python-agent with
PXE/Virtual Media based boot interface can
support rescue operation when configured appropriately.

Rescue operation can be used to boot nodes into a rescue ramdisk so
that the rescue user can access the node, in order to
provide the ability to access the node in case access to OS is not
possible. For example, if there is a need to perform manual password
reset or data recovery in the event of some failure, rescue operation
can be used.

Configuring The Bare Metal
Service

Configure the Bare Metal Service appropriately so that the service
has the information needed to boot the ramdisk before a user tries to
initiate rescue operation. This will differ somewhat between different
deploy environments, but an example of how to do this is outlined
below:

1. Create and configure ramdisk that supports rescue operation.
   Please see /install/deploy-ramdisk for detailed instructions to
   build a ramdisk.

2. Configure a network to use for booting nodes into the rescue
   ramdisk in neutron, and note the UUID or name of this network. This is
   required if you’re using the neutron DHCP provider and have Bare Metal
   Service managing ramdisk booting (the default). This can be the same
   network as your cleaning or tenant network (for flat network). For an
   example of how to configure new networks with Bare Metal Service, see
   the /install/configure-networking documentation.

3. Add the unique name or UUID of your rescue network to
   ironic.conf:

   [neutron]
   rescuing_network=<RESCUE_UUID_OR_NAME>

   Note

   This can be set per node via driver_info[‘rescuing_network’]

4. Restart the ironic conductor service.

5. Specify a rescue kernel and ramdisk or rescue ISO compatible with
   the node’s driver for pxe based boot interface or virtual-media based
   boot interface respectively.

   Example for pxe based boot interface:

   baremetal node set $NODE_UUID \
       --driver-info rescue_ramdisk=$RESCUE_INITRD_UUID \
       --driver-info rescue_kernel=$RESCUE_VMLINUZ_UUID

   See /install/configure-glance-images for details. If you
   are not using Image service, it is possible to provide images to Bare
   Metal service via hrefs.

After this, The Bare Metal Service should be ready for
rescue operation. Test it out by attempting to rescue an
active node and connect to the instance using ssh, as given below:

baremetal node rescue $NODE_UUID \
    --rescue-password <PASSWORD> --wait

ssh rescue@$INSTANCE_IP_ADDRESS

To move a node back to active state after using rescue mode you can
use unrescue. Please unmount any filesystems that were
manually mounted before proceeding with unrescue. The node unrescue can
be done as given below:

baremetal node unrescue $NODE_UUID

rescue and unrescue operations can also be
triggered via the Compute Service using the following commands:

openstack server rescue --password <password> <server>

openstack server unrescue <server>