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Based on the feedback that was received from the community at the CloudStack conference in Miami the config-drive implementation was extended to support the OpenStack config-drive implementation. This allows for easy integration with cloud-init and similar systems. 

OpenStack (cloud-init) compatibility (version 2)

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The following criteria are required for config drive in OpenStack:

 

1. Must be formatted with vfat (deprecated) or iso9660 filesystem

2. have a filesystem label of config-2

3. The files that will typically be present in the config drive are:

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• <mountdir>/openstack/version/: (only support version = latest, same approach as coreOS)

• user_data

• vendor_data.json

• meta_data.json

• network_data.json

 

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This map structure will be created beside the original CloudStack map structure. The config drive will contain the following folders and files:

 

 

• <mountdir>

• /cloudstack

• /metadata:

• availability-zone.txt  

• instance-id.txt     

• service-offering.txt

• cloud-identifier.txt  

• local-hostname.txt  

• vm-id.txt

• public-keys

• /password

• vm_password.txt

• vm_password_md5checksum (for windows VM’s)

• /user_data

• user_data.txt        (note about _ characters below in text)

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• /openstack

• /version

• User_data ==hardlink to <mountdir>/cloudstack/user_data/user_data.txt

• vendor_data.json

• meta_data.json

• network_data.json

 

 

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Content of user_data:

We make a hard link to the user_data file in the cloudstack directory (soft link does not work in iso).

Content of meta_data.json (json encoded):

• meta

• files

• network_config

• public_keys: [{‘’data’’: “ssh-key value”, type: “ssh”, name: “name of key”}]

• keys:  [{‘’data’’: “ssh-key value”, type: “ssh”, name: “name of key”}]

• hostname

• name

• launch_index

• availability_zone

• random_seed

• project_id

• devices

• uuid

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CloudStack config-drive supports the following: 

• availability-zone

• hostname

• name

• uuid

• keys

• public-keys

I.e. we leave out the content we don’t support  (list based on: https://github.com/openstack/nova/blob/39c6e442c628a881b4fce4d8b74e6b7d174f72f2/nova/api/metadata/base.py ) 

Content of vendor_data.json (json encoded):

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Vendor-Data is a way for a vendor to provide site specific information. This can be information on local mirrors, a local proxy, or a one-time registration code. It is found in the vendor_data.json file residing on ConfigDrive or the Neutron Metadata Service via 169.254.169.254/openstack/latest/vendor_data.json. By default, Cloud-Init executes the Vendor-Data on every boot. Currently, we don’t plan to support this.

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Content of network_data.json (json encoded):

Network-Data is network information found on ConfigDrive. It resides in the network_data.json file. Nova retrieves this info from Neutron. It includes fixed ip addresses, MAC addresses, port-id's, network-id's, subnet-id's, DNS name-servers, etc. Currently, we don’t plan to support this.

Is allowed to be empty {}

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Changes needed to CloudStack

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The current config-drive PR needs to be changed. We plan to create an extra OpenStack directory beside the original proposed CloudStack directory. We also need to change the label of the disk from config to config-2. The way the iso image is created needs to be adapted to make it align with the way OpenStack creates the iso img (provide extra params https://github.com/openstack/nova/blob/master/nova/virt/configdrive.py). A side effect is that  underscores will be written to the iso image as underscores and not replaced with dashes (current behaviour). Because of this, we have to update the coreOS PR and the CloudStack documentation.

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