When deploying an instance, sometimes an error occurs and deployment fails. If this happens with a new deployment, usually it is simplest to delete the failed instance and deploy again. However, if you must fix the broken instance, there is a nova rescue
command that will help you. This section explains how to use the nova rescue
command to fix broken instances.
If you are using the Vagrant environment, these steps are to be carried out on our network node under the user that has access to our OpenStack Compute credentials (as created in the Installation of command-line tools on network recipe).
Ensure that you are logged onto the network
node and that it has Internet access to allow us to install the required packages in our environment for running OVS and Neutron. If you created this node with Vagrant, you can execute the following command:
vagrant ssh network
From our network
machine, list the running instances to identify the instance you want to fix using the following steps:
nova list
rescue
mode, we can either specify the name of our instance or use the UUID:nova rescue myInstance nova rescue 6f41bb91-0f4f-41e5-90c3-7ee1f9c39e5a
The preceding commands will give you a temporary root password:
+-----------+--------------+ | Property | Value | +-----------+--------------+ | adminPass | VMHm2BEyCnKa | +-----------+--------------+
However, if the instance was created with a nova key, you will still need to use the key rather than the password to log in. The instance will be set in the RESCUE
status now.
ip netns
The preceding command gives the following example output:
qdhcp-0375e772-b021-425c-bc17-5a3263247fb8
Connect to the instance using the following commands:
sudo ip netns exec qdhcp-0375e772-b021-425c-bc17-5a3263247fb8 ssh -i demokey [email protected]
This will allow you to repair the instance.
nova unrescue myInstance
We identify a server that needs rescuing via the nova list
command. Then, we use either the server name or the server ID to set the server in rescue
mode using the nova rescue
command. This reboots the server into a rescue mode, which starts the machine from the initial image and attaches the current boot disk as a secondary. After repairing the server, we need to set it back to ACTIVE
status and reboot by using the nova unrescue
command.