Stable Release Updates (SRU)

Once upstream cloud-init has released a new version, the Ubuntu Server team backports cloud-init to previous releases via a special procedure called a “Stable Release Update” (SRU). This helps ensure that new versions of cloud-init on existing releases of Ubuntu will not experience breaking changes. Breaking changes are allowed when transitioning from one Ubuntu series to the next (Focal -> Jammy).

SRU package version

Ubuntu cloud-init packages follow the SRU release version format.

SRU testing for cloud-init

The cloud-init project has a specific process it follows when validating a cloud-init SRU, which is documented in the CloudinitUpdates wiki page.

An SRU test of cloud-init performs the following:

For each Ubuntu SRU, the Ubuntu Server team validates the new version of cloud-init on these platforms: Amazon EC2, Azure, GCE, OpenStack, Oracle, Softlayer (IBM), LXD using the integration test suite.

Test process:

The integration test suite used for validation follows these steps:

  • Install a pre-release version of cloud-init from the -proposed APT pocket (e.g., jammy-proposed).

  • Upgrade cloud-init and attempt a clean run of cloud-init to assert that the new version works properly on the specific platform and Ubuntu series.

  • Check for tracebacks and errors in behaviour.