Contribute to the code

For a run-through of the entire process, the following pages will be your best starting point:

On the rest of this page you’ll find the key resources you’ll need to start contributing to the cloud-init codebase.


Submissions to cloud-init must include testing. Unit testing and integration testing are integral parts of contributing code.

Code style and design

We generally adhere to PEP 8, and this is enforced by our use of black, isort and ruff.

Python support

Cloud-init upstream currently supports Python 3.6 and above.

Cloud-init upstream will stay compatible with a particular Python version for 6 years after release. After 6 years, we will stop testing upstream changes against the unsupported version of Python and may introduce breaking changes. This policy may change as needed.

The following table lists the cloud-init versions in which the minimum Python version changed:

Cloud-init version

Python version







Type annotations

The cloud-init codebase uses Python’s annotation support for storing type annotations in the style specified by PEP-484 and PEP-526. Their use in the codebase is encouraged.

Other resources

Feature flags

Feature flags are used as a way to easily toggle configuration at build time. They are provided to accommodate feature deprecation and downstream configuration changes.

Currently used upstream values for feature flags are set in cloudinit/ Overrides to these values should be patched directly (e.g., via quilt patch) by downstreams.

Each flag should include a short comment regarding the reason for the flag and intended lifetime.

Tests are required for new feature flags, and tests must verify all valid states of a flag, not just the default state.


When configuring apt mirrors, if ALLOW_EC2_MIRRORS_ON_NON_AWS_INSTANCE_TYPES is True cloud-init will detect that a datasource’s availability_zone property looks like an EC2 availability zone and set the ec2_region variable when generating mirror URLs; this can lead to incorrect mirrors being configured in clouds whose AZs follow EC2’s naming pattern.

As of 20.3, ALLOW_EC2_MIRRORS_ON_NON_AWS_INSTANCE_TYPES is False so we no longer include ec2_region in mirror determination on non-AWS cloud platforms.

If the old behavior is desired, users can provide the appropriate mirrors via apt: directives in cloud-config.

cloudinit.features.APT_DEB822_SOURCE_LIST_FILE = True

On Debian and Ubuntu systems, cc_apt_configure will write a deb822 compatible /etc/apt/sources.list.d/(debian|ubuntu).sources file. When set False, continue to write /etc/apt/sources.list directly.

cloudinit.features.ERROR_ON_USER_DATA_FAILURE = True

If there is a failure in obtaining user data (i.e., #include or decompress fails) and ERROR_ON_USER_DATA_FAILURE is False, cloud-init will log a warning and proceed. If it is True, cloud-init will instead raise an exception.


(This flag can be removed after Focal is no longer supported.)

cloudinit.features.EXPIRE_APPLIES_TO_HASHED_USERS = True

If EXPIRE_APPLIES_TO_HASHED_USERS is True, then when expire is set true in cc_set_passwords, hashed passwords will be expired. Previous to 22.3, only non-hashed passwords were expired.

(This flag can be removed after Jammy is no longer supported.)

cloudinit.features.NETPLAN_CONFIG_ROOT_READ_ONLY = True

If NETPLAN_CONFIG_ROOT_READ_ONLY is True, then netplan configuration will be written as a single root read-only file /etc/netplan/50-cloud-init.yaml. This prevents wifi passwords in network v2 configuration from being world-readable. Prior to 23.1, netplan configuration is world-readable.

(This flag can be removed after Jammy is no longer supported.)


Append a forward slash ‘/’ if NoCloud seedurl does not end with either a querystring or forward slash. Prior to 23.1, nocloud seedurl would be used unaltered, appending meta-data, user-data and vendor-data to without URL path separators.

(This flag can be removed when Jammy is no longer supported.)

cloudinit.features.get_features() Dict[str, bool][source]

Return a dict of applicable features/overrides and their values.