Troubleshooting Ironic

Nova returns “No valid host was found” Error

Sometimes Nova Conductor log file “nova-conductor.log” or a message returned from Nova API contains the following error:

NoValidHost: No valid host was found. There are not enough hosts available.

“No valid host was found” means that the Nova Scheduler could not find a bare metal node suitable for booting the new instance.

This in turn usually means some mismatch between resources that Nova expects to find and resources that Ironic advertised to Nova.

A few things should be checked in this case:

  1. Make sure that enough nodes are in available state, not in maintenance mode and not already used by an existing instance. Check with the following command:

    openstack baremetal node list --provision-state available --no-maintenance --unassociated

    If this command does not show enough nodes, use generic openstack baremetal node list to check other nodes. For example, nodes in manageable state should be made available:

    openstack baremetal node provide <IRONIC NODE>

    The Bare metal service automatically puts a node in maintenance mode if there are issues with accessing its management interface. Check the power credentials (e.g. ipmi_address, ipmi_username and ipmi_password) and then move the node out of maintenance mode:

    openstack baremetal node maintenance unset <IRONIC NODE>

    The node validate command can be used to verify that all required fields are present. The following command should not return anything:

    openstack baremetal node validate <IRONIC NODE> | grep -E '(power|management)\W*False'

    Maintenance mode will be also set on a node if automated cleaning has failed for it previously.

  2. Make sure that you have Compute services running and enabled:

    $ openstack compute service list --service nova-compute
    | ID | Binary       | Host        | Zone | Status  | State | Updated At                 |
    |  7 | nova-compute | | nova | enabled | up    | 2017-09-04T13:14:03.000000 |

    By default, a Compute service is disabled after 10 consecutive build failures on it. This is to ensure that new build requests are not routed to a broken Compute service. If it is the case, make sure to fix the source of the failures, then re-enable it:

    openstack compute service set --enable <COMPUTE HOST> nova-compute
  3. Starting with the Pike release, check that all your nodes have the resource_class field set using the following command:

    openstack --os-baremetal-api-version 1.21 baremetal node list --fields uuid name resource_class

    Then check that the flavor(s) are configured to request these resource classes via their properties:

    openstack flavor show <FLAVOR NAME> -f value -c properties

    For example, if your node has resource class baremetal-large, it will be matched by a flavor with property resources:CUSTOM_BAREMETAL_LARGE set to 1. See Create flavors for use with the Bare Metal service for more details on the correct configuration.

  4. If you do not use scheduling based on resource classes, then the node’s properties must have been set either manually or via inspection. For each node with available state check that the properties JSON field has valid values for the keys cpus, cpu_arch, memory_mb and local_gb. Example of valid properties:

    $ openstack baremetal node show <IRONIC NODE> --fields properties
    | Property   | Value                                                                              |
    | properties | {u'memory_mb': u'8192', u'cpu_arch': u'x86_64', u'local_gb': u'41', u'cpus': u'4'} |


    If you’re using exact match filters in the Nova Scheduler, make sure the flavor and the node properties match exactly.

  5. The Nova flavor that you are using does not match any properties of the available Ironic nodes. Use

    openstack flavor show <FLAVOR NAME>

    to compare. The extra specs in your flavor starting with capability: should match ones in['capabilities'].


    The format of capabilities is different in Nova and Ironic. E.g. in Nova flavor:

    $ openstack flavor show <FLAVOR NAME> -c properties
    | Field      | Value                            |
    | properties | capabilities:boot_option='local' |

    But in Ironic node:

    $ openstack baremetal node show <IRONIC NODE> --fields properties
    | Property   | Value                                   |
    | properties | {u'capabilities': u'boot_option:local'} |
  6. After making changes to nodes in Ironic, it takes time for those changes to propagate from Ironic to Nova. Check that

    openstack hypervisor stats show

    correctly shows total amount of resources in your system. You can also check openstack hypervisor show <IRONIC NODE> to see the status of individual Ironic nodes as reported to Nova.

  7. Figure out which Nova Scheduler filter ruled out your nodes. Check the nova-scheduler logs for lines containing something like:

    Filter ComputeCapabilitiesFilter returned 0 hosts

    The name of the filter that removed the last hosts may give some hints on what exactly was not matched. See Nova filters documentation for more details.

  8. If none of the above helped, check Ironic conductor log carefully to see if there are any conductor-related errors which are the root cause for “No valid host was found”. If there are any “Error in deploy of node <IRONIC-NODE-UUID>: [Errno 28] …” error messages in Ironic conductor log, it means the conductor run into a special error during deployment. So you can check the log carefully to fix or work around and then try again.

Patching the Deploy Ramdisk

When debugging a problem with deployment and/or inspection you may want to quickly apply a change to the ramdisk to see if it helps. Of course you can inject your code and/or SSH keys during the ramdisk build (depends on how exactly you’ve built your ramdisk). But it’s also possible to quickly modify an already built ramdisk.

Create an empty directory and unpack the ramdisk content there:

mkdir unpack
cd unpack
gzip -dc /path/to/the/ramdisk | cpio -id

The last command will result in the whole Linux file system tree unpacked in the current directory. Now you can modify any files you want. The actual location of the files will depend on the way you’ve built the ramdisk.


On a systemd-based system you can use the systemd-nspawn tool (from the systemd-container package) to create a lightweight container from the unpacked filesystem tree:

sudo systemd-nspawn --directory /path/to/unpacked/ramdisk/ /bin/bash

This will allow you to run commands within the filesystem, e.g. use package manager. If the ramdisk is also systemd-based, and you have login credentials set up, you can even boot a real ramdisk enviroment with

sudo systemd-nspawn --directory /path/to/unpacked/ramdisk/ --boot

After you’ve done the modifications, pack the whole content of the current directory back:

find . | cpio -H newc -o | gzip -c > /path/to/the/new/ramdisk


You don’t need to modify the kernel (e.g. tinyipa-master.vmlinuz), only the ramdisk part.

API Errors

The debug_tracebacks_in_api config option may be set to return tracebacks in the API response for all 4xx and 5xx errors.

Retrieving logs from the deploy ramdisk

When troubleshooting deployments (specially in case of a deploy failure) it’s important to have access to the deploy ramdisk logs to be able to identify the source of the problem. By default, Ironic will retrieve the logs from the deploy ramdisk when the deployment fails and save it on the local filesystem at /var/log/ironic/deploy.

To change this behavior, operators can make the following changes to /etc/ironic/ironic.conf under the [agent] group:

  • deploy_logs_collect: Whether Ironic should collect the deployment logs on deployment. Valid values for this option are:

    • on_failure (default): Retrieve the deployment logs upon a deployment failure.

    • always: Always retrieve the deployment logs, even if the deployment succeed.

    • never: Disable retrieving the deployment logs.

  • deploy_logs_storage_backend: The name of the storage backend where the logs will be stored. Valid values for this option are:

    • local (default): Store the logs in the local filesystem.

    • swift: Store the logs in Swift.

  • deploy_logs_local_path: The path to the directory where the logs should be stored, used when the deploy_logs_storage_backend is configured to local. By default logs will be stored at /var/log/ironic/deploy.

  • deploy_logs_swift_container: The name of the Swift container to store the logs, used when the deploy_logs_storage_backend is configured to “swift”. By default ironic_deploy_logs_container.

  • deploy_logs_swift_days_to_expire: Number of days before a log object is marked as expired in Swift. If None, the logs will be kept forever or until manually deleted. Used when the deploy_logs_storage_backend is configured to “swift”. By default 30 days.

When the logs are collected, Ironic will store a tar.gz file containing all the logs according to the deploy_logs_storage_backend configuration option. All log objects will be named with the following pattern:

<node-uuid>[_<instance-uuid>]_<timestamp yyyy-mm-dd-hh:mm:ss>.tar.gz


The instance_uuid field is not required for deploying a node when Ironic is configured to be used in standalone mode. If present it will be appended to the name.

Accessing the log data

When storing in the local filesystem

When storing the logs in the local filesystem, the log files can be found at the path configured in the deploy_logs_local_path configuration option. For example, to find the logs from the node 5e9258c4-cfda-40b6-86e2-e192f523d668:

$ ls /var/log/ironic/deploy | grep 5e9258c4-cfda-40b6-86e2-e192f523d668


When saving the logs to the filesystem, operators may want to enable some form of rotation for the logs to avoid disk space problems.

When storing in Swift

When using Swift, operators can associate the objects in the container with the nodes in Ironic and search for the logs for the node 5e9258c4-cfda-40b6-86e2-e192f523d668 using the prefix parameter. For example:

$ swift list ironic_deploy_logs_container -p 5e9258c4-cfda-40b6-86e2-e192f523d668

To download a specific log from Swift, do:

$ swift download ironic_deploy_logs_container "5e9258c4-cfda-40b6-86e2-e192f523d668_db87f2c5-7a9a-48c2-9a76-604287257c1b_2016-08-08-14:07:25.tar.gz"
5e9258c4-cfda-40b6-86e2-e192f523d668_db87f2c5-7a9a-48c2-9a76-604287257c1b_2016-08-08-14:07:25.tar.gz [auth 0.341s, headers 0.391s, total 0.391s, 0.531 MB/s]

The contents of the log file

The log is just a .tar.gz file that can be extracted as:

$ tar xvf <file path>

The contents of the file may differ slightly depending on the distribution that the deploy ramdisk is using:

  • For distributions using systemd there will be a file called journal which contains all the system logs collected via the journalctl command.

  • For other distributions, the ramdisk will collect all the contents of the /var/log directory.

For all distributions, the log file will also contain the output of the following commands (if present): ps, df, ip addr and iptables.

Here’s one example when extracting the content of a log file for a distribution that uses systemd:

$ tar xvf 5e9258c4-cfda-40b6-86e2-e192f523d668_88595d8a-6725-4471-8cd5-c0f3106b6898_2016-08-08-13:52:12.tar.gz

DHCP during PXE or iPXE is inconsistent or unreliable

This can be caused by the spanning tree protocol delay on some switches. The delay prevents the switch port moving to forwarding mode during the nodes attempts to PXE, so the packets never make it to the DHCP server. To resolve this issue you should set the switch port that connects to your baremetal nodes as an edge or PortFast type port. Configured in this way the switch port will move to forwarding mode as soon as the link is established. An example on how to do that for a Cisco Nexus switch is:

$ config terminal
$ (config) interface eth1/11
$ (config-if) spanning-tree port type edge

IPMI errors

When working with IPMI, several settings need to be enabled depending on vendors.

Enable IPMI over LAN

Machines may not have IPMI access over LAN enabled by default. This could cause the IPMI port to be unreachable through ipmitool, as shown:

$ipmitool -I lan -H ipmi_host -U ipmi_user -P ipmi_pass chassis power status
Error: Unable to establish LAN session

To fix this, enable IPMI over lan setting using your BMC tool or web app.

Troubleshooting lanplus interface

When working with lanplus interfaces, you may encounter the following error:

$ipmitool -I lanplus -H ipmi_host -U ipmi_user -P ipmi_pass power status
Error in open session response message : insufficient resources for session
Error: Unable to establish IPMI v2 / RMCP+ session

To fix that issue, please enable RMCP+ Cipher Suite3 Configuration setting using your BMC tool or web app.