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:

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

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

    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:

    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:

    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:

    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. Upon scheduling, Nova will query the Placement API service for the available resource providers (in the case of Ironic: nodes with a given resource class). If placement does not have any allocation candidates for the requested resource class, the request will result in a “No valid host was found” error. It is hence sensible to check if Placement is aware of resource providers (nodes) for the requested resource class with:

    $ openstack allocation candidate list --resource CUSTOM_BAREMETAL_LARGE='1'
    | # | allocation                  | resource provider                    | inventory used/capacity       |
    | 1 | CUSTOM_BAREMETAL_LARGE=1    | 2f7b9c69-c1df-4e40-b94e-5821a4ea0453 | CUSTOM_BAREMETAL_LARGE=0/1    |

    For Ironic, the resource provider is the UUID of the available Ironic node. If this command returns an empty list (or does not contain the targeted resource provider), the operator needs to understand first, why the resource tracker has not reported this provider to placement. Potential explanations include:

    • the resource tracker cycle has not finished yet and the resource provider will appear once it has (the time to finish the cycle scales linearly with the number of nodes the corresponding nova-compute service manages);

    • the node is in a state where the resource tracker does not consider it to be eligible for scheduling, e.g. when the node has maintenance set to True; make sure the target nodes are in available and maintenance is False;

  5. 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:

    $ 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.

  6. 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:

    $ baremetal node show <IRONIC NODE> --fields properties
    | Property   | Value                                   |
    | properties | {u'capabilities': u'boot_option:local'} |
  7. 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.

  8. 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.

  9. 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>[_<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

Why does X issue occur when I am using LACP bonding with iPXE?

If you are using iPXE, an unfortunate aspect of its design and interaction with networking is an automatic response as a Link Aggregation Control Protocol (or LACP) peer to remote switches. iPXE does this for only the single port which is used for network booting.

In theory, this may help establish the port link-state faster with some switch vendors, but the official reasoning as far as the Ironic Developers are aware is not documented for iPXE. The end result of this is that once iPXE has stopped responding to LACP messages from the peer port, which occurs as part of the process of booting a ramdisk and iPXE handing over control to a full operating-system, switches typically begin a timer to determine how to handle the failure. This is because, depending on the mode of LACP, this can be interpreted as a switch or network fabric failure.

This may demonstrate as any number of behaviors or issues from ramdisks finding they are unable to acquire DHCP addresses over the network interface to downloads abruptly stalling, to even minor issues such as LLDP port data being unavailable in introspection.


  • Ironic’s agent doesn’t officially support LACP and the Ironic community generally believes this may cause more problems than it would solve. During the Victoria development cycle, we added retry logic for most actions in an attempt to navigate the worst-known default hold-down timers to help ensure a deployment does not fail due to a short-lived transitory network connectivity failure in the form of a switch port having moved to a temporary blocking state. Where applicable and possible, many of these patches have been backported to supported releases, however users of the iSCSI deployment interface will see the least capability for these sorts of situations to be handled automatically. These patches also require that the switchport has an eventual fallback to a non-bonded mode. If the port remains in a blocking state, then traffic will be unable to flow and the deloyment is likely to time out.

  • If you must use LACP, consider passive LACP negotiation settings in the network switch as opposed to active. The difference being with passive the connected workload is likely a server where it should likely request the switch to establish the Link Aggregate. This is instead of being treated as if it’s possibly another switch.

  • Consult your switch vendor’s support forums. Some vendors have recommended port settings for booting machines using iPXE with their switches.

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.

Why are my nodes stuck in a “-ing” state?

The Ironic conductor uses states ending with ing as a signifier that the conductor is actively working on something related to the node.

Often, this means there is an internal lock or reservation set on the node and the conductor is downloading, uploading, or attempting to perform some sort of Input/Output operation.

In the case the conductor gets stuck, these operations should timeout, but there are cases in operating systems where operations are blocked until completion. These sorts of operations can vary based on the specific environment and operating configuration.

What can cause these sorts of failures?

Typical causes of such failures are going to be largely rooted in the concept of iowait, either in the form of downloading from a remote host or reading or writing to the disk of the conductor. An operator can use the iostat tool to identify the percentage of CPU time spent waiting on storage devices.

The fields that will be particularly important are the iowait, await, and tps ones, which can be read about in the iostat manual page.

In the case of network file systems, for backing components such as image caches or distributed tftpboot or httpboot folders, IO operations failing on these can, depending on operating system and underlying client settings, cause threads to be stuck in a blocking wait state, which is realistically undetectable short the operating system logging connectivity errors or even lock manager access errors.

For example with nfs, the underlying client recovery behavior, in terms of soft, hard, softreval, nosoftreval, will largely impact this behavior, but also NFS server settings can impact this behavior. A solid sign that this is a failure, is when an ls /path/to/nfs command hangs for a period of time. In such cases, the Storage Administrator should be consulted and network connectivity investigated for errors before trying to recover to proceed.

File Size != Disk Size

An easy to make misconception is that a 2.4 GB file means that only 2.4 GB is written to disk. But if that file’s virtual size is 20 GB, or 100 GB things can become very problematic and extend the amount of time the node spends in deploying and deploy wait states.

Again, these sorts of cases will depend upon the exact configuration of the deployment, but hopefully these are areas where these actions can occur.

  • Conversion to raw image files upon download to the conductor, from the [DEFAULT]force_raw_images option, in particular with the iscsi deployment interface. Users using glance and the direct deployment interface may also experience issues here as the conductor will cache the image to be written which takes place when the [agent]image_download_source is set to http instead of swift.

  • Write of a QCOW2 file over the iscsi deployment interface from the conductor to the node being deployed can result in large amounts of “white space” to be written to be transmitted over the wire and written to the end device.


The QCOW2 image conversion utility does consume quite a bit of memory when converting images or writing them to the end storage device. This is because the files are not sequential in nature, and must be re-assembled from an internal block mapping. Internally Ironic limits this to 1GB of RAM. Operators performing large numbers of deployments may wish to explore the direct deployment interface in these sorts of cases in order to minimize the conductor becoming a limiting factor due to memory and network IO.

Why are my nodes stuck in a “wait” state?

The Ironic conductor uses states containing wait as a signifier that the conductor is waiting for a callback from another component, such as the Ironic Python Agent or the Inspector. If this feedback does not arrive, the conductor will time out and the node will eventually move to a failed state. Depending on the configuration and the circumstances, however, a node can stay in a wait state for a long time or even never time out. The list of such wait states includes:

  • clean wait for cleaning,

  • inspect wait for introspection,

  • rescue wait for rescueing, and

  • wait call-back for deploying.

Communication issues between the conductor and the node

One of the most common issues when nodes seem to be stuck in a wait state occur when the node never received any instructions or does not react as expected: the conductor moved the node to a wait state but the node will never call back. Examples include wrong ciphers which will make ipmitool get stuck or BMCs in a state where they accept commands, but don’t do the requested task (or only a part of it, like shutting off, but not starting). It is useful in these cases to see via a ping or the console if and which action the node is performing. If the node does not seem to react to the requests sent be the conductor, it may be worthwhile to try the corresponding action out-of-band, e.g. confirm that power on/off commands work when directly sent to the BMC. The section on IPMI errors. above gives some additional points to check. In some situations, a BMC reset may be necessary.

Ironic Python Agent stuck

Nodes can also get remain in a wait state when the component the conductor is waiting for gets stuck, e.g. when a hardware manager enters a loop or is waiting for an event that is never happening. In these cases, it might be helpful to connect to the IPA and inspect its logs, see the trouble shooting guide of the ironic-python-agent (IPA) on how to do this.

Deployments fail with “failed to update MAC address”

The design of the integration with the Networking service (neutron) is such that once virtual ports have been created in the API, their MAC address must be updated in order for the DHCP server to be able to appropriately reply.

This can sometimes result in errors being raised indicating that the MAC address is already in use. This is because at some point in the past, a virtual interface was orphaned either by accident or by some unexpected glitch, and a previous entry is still present in Neutron.

This error looks something like this when reported in the ironic-conductor log output.:

Failed to update MAC address on Neutron port 305beda7-0dd0-4fec-b4d2-78b7aa4e8e6a.: MacAddressInUseClient: Unable to complete operation for network 1e252627-6223-4076-a2b9-6f56493c9bac. The mac address 52:54:00:7c:c4:56 is in use.

Because we have no idea about this entry, we fail the deployment process as we can’t make a number of assumptions in order to attempt to automatically resolve the conflict.

How did I get here?

Originally this was a fairly easy issue to encounter. The retry logic path which resulted between the Orchestration (heat) and Compute (nova) services, could sometimes result in additional un-necessary ports being created.

Bugs of this class have been largely resolved since the Rocky development cycle. Since then, the way this can become encountered is due to Networking (neutron) VIF attachments not being removed or deleted prior to deleting a port in the Bare Metal service.

Ultimately, the key of this is that the port is being deleted. Under most operating circumstances, there really is no need to delete the port, and VIF attachments are stored on the port object, so deleting the port CAN result in the VIF not being cleaned up from Neutron.

Under normal circumstances, when deleting ports, a node should be in a stable state, and the node should not be provisioned. If the baremetal port delete command fails, this may indicate that a known VIF is still attached. Generally if they are transitory from cleaning, provisioning, rescuing, or even inspection, getting the node to the available state wil unblock your delete operation, that is unless there is a tenant VIF attahment. In that case, the vif will need to be removed from with-in the Bare Metal service using the baremetal node vif detach command.

A port can also be checked to see if there is a VIF attachment by consulting the port’s internal_info field.


The maintenance flag can be used to force the node’s port to be deleted, however this will disable any check that would normally block the user from issuing a delete and accidently orphaning the VIF attachment record.

How do I resolve this?

Generally, you need to identify the port with the offending MAC address. Example:

openstack port list –mac-address 52:54:00:7c:c4:56

From the command’s output, you should be able to identify the id field. Using that, you can delete the port. Example:

openstack port delete <id>


Before deleting a port, you should always verify that it is no longer in use or no longer seems applicable/operable. If multiple deployments of the Bare Metal service with a single Neutron, the possibility that a inventory typo, or possibly even a duplicate MAC address exists, which could also produce the same basic error message.

My test VM image does not deploy – mount point does not exist

What is likely occuring

The image attempting to be deployed likely is a partition image where the file system that the user wishes to boot from lacks the required folders, such as /dev and /proc, which are required to install a bootloader for a Linux OS image

It should be noted that similar errors can also occur with whole disk images where we are attempting to setup the UEFI bootloader configuration. That being said, in this case, the image is likely invalid or contains an unexpected internal structure.

Users performing testing may choose something that they believe will work based on it working for virtual machines. These images are often attractive for testing as they are generic and include basic support for establishing networking and possibly installing user keys. Unfortunately, these images often lack drivers and firmware required for many different types of physical hardware which makes using them very problematic. Additionally, images such as Cirros do not have any contents in the root filesystem (i.e. an empty filesystem), as they are designed for the ramdisk to write the contents to disk upon boot.

How do I not encounter this issue?

We generally recommend using diskimage-builder or vendor supplied images. Centos, Ubuntu, Fedora, and Debian all publish operating system images which do generally include drivers and firmware for physical hardware. Many of these published “cloud” images, also support auto-configuration of networking AND population of user keys.

Issues with autoconfigured TLS

These issues will manifest as an error in ironic-conductor logs looking similar to (lines are wrapped for readability):

ERROR ironic.drivers.modules.agent_client [-]
Failed to connect to the agent running on node d7c322f0-0354-4008-92b4-f49fb2201001
for invoking command clean.get_clean_steps. Error:
HTTPSConnectionPool(host='', port=9999): Max retries exceeded with url:
/v1/commands/?wait=true&agent_token=<token> (Caused by
SSLError(SSLError(1, '[SSL: CERTIFICATE_VERIFY_FAILED] certificate verify failed (_ssl.c:897)'),)):
requests.exceptions.SSLError: HTTPSConnectionPool(host='', port=9999):
Max retries exceeded with url: /v1/commands/?wait=true&agent_token=<token>
(Caused by SSLError(SSLError(1, '[SSL: CERTIFICATE_VERIFY_FAILED] certificate verify failed (_ssl.c:897)'),))

The cause of the issue is that the Bare Metal service cannot access the ramdisk with the TLS certificate provided by the ramdisk on first heartbeat. You can inspect the stored certificate in /var/lib/ironic/certificates/<node>.crt.

You can try connecting to the ramdisk using the IP address in the log message:

curl -vL https://<IP address>:9999/v1/commands \
    --cacert /var/lib/ironic/certificates/<node UUID>.crt

You can get the detailed information about the certificate using openSSL:

openssl x509 -text -noout -in /var/lib/ironic/certificates/<node UUID>.crt

Clock skew

One possible source of the problem is a discrepancy between the hardware clock on the node and the time on the machine with the Bare Metal service. It can be detected by comparing the Not Before field in the openssl output with the timestamp of a log message.

The recommended solution is to enable the NTP support in ironic-python-agent by passing the ipa-ntp-server argument with an address of an NTP server reachable by the node.

If it is not possible, you need to ensure the correct hardware time on the machine. Keep in mind a potential issue with timezones: an ability to store timezone in hardware is pretty recent and may not be available. Since ironic-python-agent is likely operating in UTC, the hardware clock should also be set in UTC.


Microsoft Windows uses local time by default, so a machine that has previously run Windows will likely have wrong time.

I changed ironic.conf, and now I can’t edit my nodes.

Whenever a node is created in ironic, default interfaces are identified as part of driver composition. This maybe sourced from explicit default values which have been set in ironic.conf or by the interface order for the enabled interfaces list. The result of this is that the ironic-conductor cannot spawn a task using the composed driver, as a portion of the driver is no longer enabled. This makes it difficult to edit or update the node if the settings have been changed.

For example, with networking interfaces, if you have default_network_interface=neutron or enabled_network_interfaces=neutron,flat in your ironic.conf, nodes would have been created with the neutron network interface.

This is because default_network_interface overrides the setting for new nodes, and that setting is saved to the database nodes table.

Similarly, the order of enabled_network_interfaces takes priority, and the first entry in the list is generally set to the default for the node upon creation, and that record is saved to the database nodes table.

The only case where driver composition does not calculate a default is if an explicit value is provided upon the creation of the node.

Example failure

A node in this state, when the network_interface was saved as neutron, yet the neutron interface is no longer enabled will fail basic state transition requests.:

$ baremetal node manage 7164efca-37ab-1213-1112-b731cf795a5a Could not find the following interface in the ‘’ entrypoint: neutron. Valid interfaces are [‘flat’]. (HTTP 400)

How to fix this?

Revert the changes you made to ironic.conf.

This applies to any changes to any default_*_interface options or the order of interfaces in the for the enabled_*_interfaces options.

Once the conductor has been restarted with the updated configuration, you should now be able to update the interface using the baremetal node set command. In this example we use the network_interface as this is most commonly where it is encountered.:

$ baremetal node set $NAME_OR_UUID –network-interface flat


There are additional paths one can take to remedy this sort of issue, however we encourage operators to be mindful of operational consistency when making major configuration changes.

Once you have updated the saved interfaces, you should be able to safely return the ironic.conf configuration change in changing what interfaces are enabled by the conductor.

I’m getting Out of Memory errors

This issue, also known as the “the OOMKiller got my conductor” case, is where your OS system memory reaches a point where the operating system engages measures to shed active memory consumption in order to prevent a complete failure of the machine. Unfortunately this can cause unpredictable behavior.

How did I get here?

One of the major consumers of memory in a host running an ironic-conductor is transformation of disk images using the qemu-img tool. This tool, because the disk images it works with are both compressed and out of linear block order, requires a considerable amount of memory to efficently re-assemble and write-out a disk to a device, or to simply convert the format such as to a raw image.

By default, ironic’s configuration limits this conversion to 1 GB of RAM for the process, but each conversion does cause additional buffer memory to be used, which increases overall system memory pressure. Generally memory pressure alone from buffers will not cause an out of memory condition, but the multiple conversions or deployments running at the same time CAN cause extreme memory pressure and risk the system running out of memory.

How do I resolve this?

This can be addressed a few different ways:

  • Use raw images, however these images can be substantially larger and require more data to be transmitted “over the wire”.

  • Add more physical memory.

  • Add swap space.

  • Reduce concurrency, possibly via another conductor or changing the nova-compute.conf max_concurrent_builds parameter.

  • Or finally, adjust the [DEFAULT]minimum_required_memory parameter in your ironic.conf file. The default should be considered a “default of last resort” and you may need to reserve additional memory. You may also wish to adjust the [DEFAULT]minimum_memory_wait_retries and [DEFAULT]minimum_memory_wait_time parameters.