Variables Guide

The goal of this document is to guide users to correctly configure the most important variables in OS Migrate. For a complete listing of variables configurable for each Ansible role, refer to the documentation of the individual roles.

General variables

Resource filters

Resource filters allow the user to control which resources will be migrated. The filters match against resource names.

The filters work both during export and during import, and it is not required that the same value is used during export and import. This feature can be used e.g. to export a subset of the existing resources, and then during import further limit the subset of resources being imported into batches.

The value of a filter variable is a list, where each item can be a string (exact match) or a dictionary with regex key (regular expression match). A resource is exported if it matches at least one of the list items.

  - my_net
  - other_net
  - regex: ^myprefix_.*

The above example says: Export only networks named my_net or other_net or starting with myprefix_.

The filters default to:

- regex: .*

meaning “export all resources”. (The set of resources exported will still be limited to those you can see with the authentication variables you used.)

Sometimes two roles use the same variable where this makes sense, especially for attached resources. E.g. roles export_security_groups and export_security_group_rules both use os_migrate_security_groups_filter. Similarly, export_routers and export_router_interfaces both use os_migrate_routers_filter.

List of the currently implemented filters with default values you can copy into your variables file and customize:

  - regex: .*
  - regex: .*
  - regex: .*
  - regex: .*
  - regex: .*
  - regex: .*
  - regex: .*
  - regex: .*
  - regex: .*
  - regex: .*

Conversion host variables

The following variables are those that need to be configured prior to running OS Migrate.

Conversion host name

The conversion hosts might be configured using different names, this is in case an operator needs to have them registered with the subscription manager and avoid collisions with the names.

The conversion hosts names can be customized using the following variables:


By default, these variables have the same value for both conversion hosts os_migrate_conv_src and os_migrate_conv_dst respectively.

Conversion host image name

The conversion host image is the guest configure to execute the instances migrations.

The variables to be configured are:


This image must be accessible to both tenants/projects prior to executing the conversion host deployment playbook. The variables default to os_migrate_conv, so if a conversion host image is uploaded to Glance as public image with this name (in both src and dst clouds), these variables do not need to be configured explicitly.

Make sure this image exists in Glance on both clouds. Currently it should be a CentOS 8 Cloud Image or RHEL 8 KVM Guest Image.

Conversion host flavor name

The conversion host flavor defines the compute, memory, and storage capacity that will be allocated for the conversion hosts. It needs to have at least a volume with 20GB.

The variables to be configured are:


Usually, ‘m1.medium’ will suffice this requirement, but again, it can be different between deployments.

Conversion host external network name

The external network configuration allows the connection of the conversion host router for external access, this external network must be able to allocate floating IPs reachable between both conversion hosts.

Set the name of the external (public) network to which conversion host private subnet will be attached via its router, for source and destination clouds respectively, via these variables:


This is not required if you are attaching your conversion host to pre-existing network (when os_migrate_src/dst_conversion_manage_network is false).

Other conversion host dependency names

In addition to the name variables described above, it is possible to customize names of other conversion host dependency resources:


Conversion host availablility zone management

Availability zones are defined by attaching specific metadata information to an aggregate:


The conversion host can set logical abstractions for partitioning instances to a specific set of hosts belonging to an aggregate.

The default is false (meaning no specification provided).

Conversion host network management

It is possible to disable creation and deletion of conversion host private network by setting these variables to false:


This disables creation of the network, the subnet, and the router that typically makes the conversion host reachable from outside the cloud.

When disabling network management like this, you’ll need pre-existing network that the conversion host can attach to and use it to talk to the other conversion host. Set these network name variables accordingly:


Conversion host floating IP management

OS Migrate can be told to not attempt to create any floating IPs on the conversion hosts. This can be useful when attaching a conversion host to some public network, where its IP address will be automatically reachable from outside. The variables to control whether conversion hosts should have floating IPs are:


When the conversion hosts are removed, the required and assigned floating IPs need to be detached or removed.

The following variables allow to change the behavior of deleting of detaching the floating IP when deleting the conversion hosts (default: true):


When the corresponding …_manage_fip variable is set to false, floating IP deletion is not attempted even if …_delete_fip is set to true.

Conversion host specific floating IP

Each conversion host needs to have a floating IP, these floating IPs can be assigned automatically or defined by the operator with the usage of the following variables:


When using this variable to specify an exact IP address, the floating IP must already exist and be available for attaching.

Attaching conversion hosts onto public networks

A combination of variables described earlier can be used to attach the conversion hosts directly onto pre-existing public networks. We need to make sure that we don’t try to create any private network, we don’t try to create a floating IP, and we set the conversion host network names accordingly:

os_migrate_src_conversion_manage_network: false
os_migrate_dst_conversion_manage_network: false
os_migrate_src_conversion_manage_fip: false
os_migrate_dst_conversion_manage_fip: false
os_migrate_src_conversion_net_name: some_public_net_src
os_migrate_dst_conversion_net_name: some_public_net_dst

Conversion host boot from volume

The conversion hosts can be created as boot-from-volume servers in either cloud. The variables that control the behavior are:


The default is false (meaning boot from Nova local disk).

When creating boot-from-volume conversion hosts, it is possible to customize the size in GB for the boot volume:


The size should be 20 or more, the default is 20.

Conversion host RHEL variables

When using RHEL as conversion host, set the SSH user name as follows:

os_migrate_conversion_host_ssh_user: cloud-user

It is also necessary to set RHEL registration variables. The variables part of this role are set to omit by default.

The variables os_migrate_conversion_rhsm_auto_attach and os_migrate_conversion_rhsm_activationkey are mutually exclusive, given that, they are both defaulted to omit.

Typically the only registration variables to set are:


In this case, os_migrate_conversion_rhsm_auto_attach should be set to True in order to fetch automatically the content once the node is registered.



For this case, os_migrate_conversion_rhsm_auto_attach must be left undefined with its default value of omit.

The complete list of registration variables corresponds to the redhat_subscription Ansible module. In OS Migrate they are named as follows:


Additionally is possible to enable specific repositories in the conversion hosts using the following variable:


The os_migrate_conversion_rhsm_repositories variable is a list of those repositories that will be enabled on the conversion host.

Enabling password-based SSH access to the conversion hosts

When required, a user can configure password-based SSH access to the conversion hosts, this feature might be useful for debugging when the private key of the hosts is not available anymore.

The variables required in order to configure the password-based access are named as follows:


The variable os_migrate_conversion_host_ssh_user_enable_password_access is set by default to false, and the variable os_migrate_conversion_host_ssh_user_password is set by default to the following string weak_password_disabled_by_default.

The user enabled to access the conversion hosts with password-based authentication is the one defined in the os_migrate_conversion_host_ssh_user variable.

Running custom bash scripts in the conversion hosts

It is possible to run custom bash scripts in the conversion hosts before and after configuring their content. The content of the conversion hosts is a set of required packages and in the case of using RHEL then the configuration of the subscription manager.

The variables allowing to run the custom scripts are:


The Ansible module used to achieve this is shell, so users can execute a simple one-liner command, or more complex scripts like the following examples:

os_migrate_src_conversion_host_pre_content_hook: |
  ls -ltah
  echo "hello world"
  df -h


os_migrate_src_conversion_host_pre_content_hook: "echo 'this is a simple command'"

Disabling the subscription manager tasks

It is possible to disable the subscription manager native tasks by setting to false the following variable:


This will skip the tasks related to RHSM when using RHEL in the conversion hosts. Disabling RHSM can be useful in those cases where the operator has custom scripts they need to use instead the standard Ansible module.

OpenStack REST API TLS variables

If either of your clouds uses TLS endpoints that are not trusted by the Migrator host by default (e.g. using self-signed certificates), or if the Migrator host should authenticate itself via key+cert, you will need to set TLS-related variables.

  • os_migrate_src_validate_certs / os_migrate_dst_validate_certs - Setting these to false disables certificate validity checks of the source/destination API endpoints.

  • os_migrate_src_ca_cert / os_migrate_dst_ca_cert - These variables allow you to specify a custom CA certificate that should be used to validate the source/destination API certificates.

  • os_migrate_src_client_cert, os_migrate_src_client_key / os_migrate_dst_client_cert, os_migrate_dst_client_key - If the Migrator host should authenticate itself using a TLS key + certificate when talking to source/destination APIs, set these variables.

Workload import/export variables

  • os_migrate_workload_stop_before_migration - Set to true if you wish for os_migrate to stop your workloads/vms prior to migration. Note that only workloads/vms in SHUTOFF state will be migrated.