Datasources are sources of configuration data for cloud-init that typically come from the user (i.e. userdata) or come from the cloud that created the configuration drive (i.e. metadata). Typical userdata would include files, YAML, and shell scripts while typical metadata would include server name, instance id, display name and other cloud specific details.
Since there are multiple ways to provide this data (each cloud solution seems to prefer its own way) internally a datasource abstract class was created to allow for a single way to access the different cloud systems methods to provide this data through the typical usage of subclasses.
Any metadata processed by cloud-init’s datasources is persisted as
/run/cloud-init/instance-data.json. Cloud-init provides tooling to quickly
introspect some of that data. See Instance Metadata for more
The following is a list of documents for each supported datasource:
The datasource objects have a few touch points with cloud-init. If you are interested in adding a new datasource for your cloud platform you will need to take care of the following items:
Identify a mechanism for positive identification of the platform: It is good practice for a cloud platform to positively identify itself to the guest. This allows the guest to make educated decisions based on the platform on which it is running. On the x86 and arm64 architectures, many clouds identify themselves through DMI data. For example, Oracle’s public cloud provides the string ‘OracleCloud.com’ in the DMI chassis-asset field.
cloud-init enabled images produce a log file with details about the platform. Reading through this log in
/run/cloud-init/ds-identify.logmay provide the information needed to uniquely identify the platform. If the log is not present, you can generate it by running from source
./tools/ds-identifyor the installed location
The mechanism used to identify the platform will be required for the ds-identify and datasource module sections below.
Add datasource module ``cloudinit/sources/DataSource<CloudPlatform>.py``: It is suggested that you start by copying one of the simpler datasources such as DataSourceHetzner.
Add tests for datasource module: Add a new file with some tests for the module to
cloudinit/sources/test_<yourplatform>.py. For example see
Update ds-identify: In systemd systems, ds-identify is used to detect which datasource should be enabled or if cloud-init should run at all. You’ll need to make changes to
Add tests for ds-identify: Add relevant tests in a new class to
tests/unittests/test_ds_identify.py. You can use
TestOracleas an example.
Add your datasource name to the builtin list of datasources: Add your datasource module name to the end of the
Add your cloud platform to apport collection prompts: Update the list of cloud platforms in
cloudinit/apport.py. This list will be provided to the user who invokes
Enable datasource by default in ubuntu packaging branches: Ubuntu packaging branches contain a template file
debian/cloud-init.templatesthat ultimately sets the default datasource_list when installed via package. This file needs updating when the commit gets into a package.
Add documentation for your datasource: You should add a new file in